COMBINATIONS OF SELECTED SULFONYLUREA HERBICIDES WITH S- METOLACHLOR FOR NUTSEDGE CONTROL IN TOMATOES Except where reference is made to the work of others, the work described in this thesis is my own or was done in collaboration with my advisory committee. This thesis does not include proprietary or classified information. ____________________________________ Collin Wayne Adcock Certified of Approval: ________________________ ________________________ Glenn R. Wehtje Wheeler G. Foshee, III, Chair Professor Assistant Professor Agronomy and Soils Horticulture ________________________ ________________________ Charles H. Gilliam George T. Flowers Professor Interim Dean Horticulture Graduate School COMBINATIONS OF SELECTED SULFONYLUREA HERBICIDES WITH S- METOLACHLOR FOR NUTSEDGE CONTROL IN TOMATOES Collin Wayne Adcock A Thesis Submitted to the Graduate Faculty of Auburn University in Partial Fulfillment of the Requirements for the Degree of Masters of Science Auburn, Alabama May 10, 2007 iii COMBINATIONS OF SELECTED SULFONYLUREA HERBICIDES WITH S- METOLACHLOR FOR NUTSEDGE CONTROL IN TOMATOES Collin Wayne Adcock Permission is granted to Auburn University to make copies of this thesis at its discretion, upon request of individuals or institutions and at their expense. The author reserves all publication rights. ____________________________ Signature of Author ____________________________ Date of Graduation iv VITA Collin Wayne Adcock was born on October 4, 1981 in Opelika, Alabama. He is the son of Wayne and Joye Adcock. He has one sister, Allison and a brother-in-law Jeffery. He graduated from Handley High School in Roanoke, Alabama in May of 2000 and entered Southern Union State Community College in August of 2000. He then transferred to Auburn University in August of 2002 and graduated in May of 2004 with a Bachelor of Science in Horticulture and a minor in Agronomy and Soils. He then went to work with Campbell, Martin, and Shaw LLC., a landscape company in Huntsville, Alabama. In January of 2005 he entered graduate school at Auburn University and began to pursue a Masters of Science working under the supervision of Wheeler G. Foshee, III. While at Auburn, Collin was employed as a graduate research assistant and also as a graduate teaching assistant. He received his Masters of Science degree on May 11, 2007. v THESIS ABSTRACT COMBINATIONS OF SELECTED SULFONYLUREA HERBICIDES WITH S- METOLACHLOR FOR NUTSEDGE CONTROL IN TOMATOES Collin Wayne Adcock Masters of Science, May 10, 2007 (B.S. Auburn University, 2004) 84 Typed pages Directed by Wheeler G. Foshee III In 2005 and 2006 field studies were conducted at Auburn University?s E.V. Smith Research Station, Chilton County Research and Extension Center, and Wiregrass Research and Extension Center to evaluate combinations of selected sulfonylureas and S- metolachlor in controlling yellow nutsedge. In the summer of 2005 a study was conducted to evaluate nutsedge punctures with halosulfuron and S-metolachlor alone or in combinations. In bareground and plastic mulch, both S-metolachlor and halosulfuron resulted in a rate-dependent reduction in yellow nutsedge foliage. Main effects of both herbicides were significant, but the interaction was not, so theses two herbicides were additive with respect to their ability to control nutsedge. The most effective treatment was the high rate of either halosulfuron or S-metolachlor alone. vi In May of 2006, two field studies were conducted to evaluate combinations of halosulfuron and S-metolachlor on tomato yields. No interactions were observed so data was pooled over both locations. Nontreated bareground plots yielded the lowest of all treatments. Complete control of all weed species except yellow nutsedge was obtained in all plastic mulch treatments. Nutsedge growth resulted in 143 g of biomass and 31 punctures per plot. Plastic mulch treatments yielded 10.8 kg/plot of tomatoes, resulting in a three-fold increase compared to bareground. S-metolachlor PRE neither improved nutsedge control or tomato yield relative to plastic mulch treatments. S-metolachlor plus halosulfuron applied PRE, produced similar results compared to S-metolachlor PRE. S- metolachlor PRE followed by halosulfuron POST was the most effective treatment. However, nutsedge biomass and punctures were reduced 50 and 29% compared to plastic mulch alone. There was no PRE-applied treatment identified that reduced nutsedge penetration. Halosulfuron POST remains the most effective treatment in controlling nutsedge. Overall efficacy with respect to preventing plastic mulch punctures was marginal; as a result plastic mulch is largely limited to a single cropping season. In the fall of 2006 another field study was conducted to evaluate herbigation utilizing selected sulfonylureas and S-metolachlor combinations. All injected treatments compared to PRE applications had lower nutsedge biomass. Injected treatments resulted in a decrease of nutsedge biomass and number of punctures along with a higher percent control for all contrasts except the S-metolachlor/trifloxysulfuron tank mixture. Results from this one-time field study appear promising for this type of application. There is a need for further studies to determine the efficacy of this cost-saving application method should be repeated. vii ACKNOWLEDGEMENTS The author would like to express thanks, in no particular order, to Wheeler G. Foshee for his superb and outstanding wisdom, guidance, support, friendship, devotion and confidence in him in his pursuit to obtain his degree. The author would also like to thank Glenn R. Wehtje for his help and assistance. The author also extends appreciation to Charles H. Gilliam. Special thanks are also given to Edgar Vinson for the many hot days spent out in the field along with his knowledge, friendship, and encouragement. Without your help, Edgar, I would have not made it through those 98 degree days in May, June, July, and August. Gratitude is also given to E.V. Smith Research and Extension Center and the Chilton County Area Research and Extension Center employee?s. Recognition goes out to all the fellow graduate students and others whom the author formed relationships and friendships with during his time at Auburn (Emily, Brandon, Jared, Rob, Brad, Diana, Matt, Jeremy, Charlie, Scott, and others). The author would also like to thank his mother, father, sister, brother-in-law, and grandmothers. Without the support, love, and prayers of these people this degree would not have even been possible. The author greatly appreciates all of the sacrifices his parents made to make this degree feasible, both financially and emotionally; they will never be forgotten. Last, but certainly not least, the author would like to thank the Lord God Almighty. Through Jesus Christ all things are possible. viii Style manual or journal used: Hort Science Computer software used: Microsoft Word 2003, Microsoft Excel 2003, SAS V.9.1 - ix TABLE OF CONTENTS LIST OF TABLES???????????????????????????..x LIST OF FIGURES??????????????????????????..xiii I. INTRODUCTION AND LITERATURE REVIEW?????????.??..1 II. EVALUATION OF COMBINING SULFONYLUREAS AND S- METOLACHLOR TO CONTROL NUTSEDGE UNDERNEATH POLYETHELENEMULCH????????????????????..19 III. EVALUATION OF S-METOLACHLOR AND HALOSULFURON COMBINATIONS FOR MANAGEMENT OF NUTSEDGE IN TOMATO YIELD????..??????????????????????...?.. 28 IV EVALUATION OF INJECTING COMBINATIONS OF SULFONYLUREAS AND S-METOLACHLOR THROUGH DRIP IRRIGATION SYSTEMS??..49 V FINAL DISCUSSION???????????????????????62 APPENDIX ?????????????????????????????...66 x LIST OF TABLES Chapter II: 1. Main effects of S-metolachlor and halosulfuron when soil applied as a tank mixture and followed either with or without plastic mulch for the control of yellow nutsedge conducted at E.V. Smith Research Center, Tallassee, Alabama and Wiregrass Research and Extension Center, Headland, Alabama in the summer of 2005??????????????????????????????...27 Chapter III: 1. Effects of herbicide and mulch on production of field grown tomatoes in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton, Alabama????????.?38 2. Effects of herbicide and mulch on yellow nutsedge suppression at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton, Alabama ??????????????????????39 3. Effects of herbicide and mulch on yellow nutsedge biomass at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton, Alabama ?????????????????????????40 xi Chapter IV: 1. Effects of herbicide applications (sprayed vs. injection) on yellow nutsedge biomass conducted at E.V. Smith Research Center, Tallassee, Alabama in the summer of 2006???????. ????????????????..?????.?.57 2. Effects of herbicide applications (sprayed vs. injection) on yellow nutsedge suppression conducted at E.V. Smith Research Center, Tallassee, Alabama in the summer of 2006?????????..??????.??????...??..?58 xii LIST OF FIGURES Chapter III: 1. Effects of herbicides and mulch on yield of field tomatoes pooled over two locations in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton, Alabama. ????????????????????????????.??..??41 2. Effects of herbicide and mulch on total marketable number of field grown tomatoes in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton, Alabama??????42 3. Effects of herbicide and mulch on total unmarketable number of field grown tomatoes in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton, Alabama?..????...?????????????????????..?.43 4. Effects of herbicide and mulch on total ummarketable weight of field grown tomatoes in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton Alabama.?????????...???.???????????????...44 5. Effects of herbicide and mulch on percent control of yellow nutsedge of field grown tomatoes in the summer of 2006 at E.V. Smith Research Center, Tallassee, xiii Alabama and Chilton County Research and Extension Center, Clanton, Alabama ??.?...????????????????.????????????..45 6. Effects of herbicide and mulch on yellow nutsedge punctures through polyethylene mulch in field grown tomatoes in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton, Alabama ??...?????????????.???????.?...46 7. Effects of herbicide and mulch on yellow nutsedge punctures per square foot through polyethylene mulch in field grown tomatoes in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton, Alabama???????.?????????..?.47 8. Effects of herbicide and mulch on yellow nutsedge biomass in field grown tomatoes in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton, Alabama ?????...48 Chapter IV: 1. Effects of herbicide applications (sprayed vs. injection) on yellow nutsedge punctures conducted at E.V. Smith Research Center, Tallassee, Alabama in the summer of 2006..??????????????.??????????.?59 2. Effects of herbicide and mulch (sprayed vs. injection) on yellow nutsedge percent control conducted at E.V. Smith Research Center, Tallassee, Alabama in the summer of 2006?....?????????????????????.??...60 3. Effects of herbicide and mulch (sprayed vs. injection) on yellow nutsedge biomass conducted at E.V. Smith Research Center, Tallassee, Alabama in the summer of 2006?...?????.??????????.?????????????..61 1 CHAPTER 1 INTRODUCTION AND LITERATURE REVIEW Weed control can be a significant problem in commercial production of many vegetable crops resulting in excessive weed competition that may cause substantial yield reduction. Weed control in vegetable crop production is one of the most difficult situations faced by producers all over the world (Gilreath and Santos, 2004a). In many of these situations, vegetable crops do not possess the competitive capabilities to overcome weeds for resources like water, nutrients, light, and space (Gilreath and Santos, 2004a). One of the most troublesome weeds in these cropping systems is nutsedge (Earl et al., 2004). Cyperus esculentus (yellow nutsedge) is widespread in nearly all areas where commercial vegetable crops are grown. Like other weeds, nutsedge requires cultural and chemical control (Kemble et al., 2004a). One of the biggest problems in chemical control of nutsedge is the limited number of herbicides labeled for use in vegetable crops (Kemble et al., 2004a). Nutsedge belongs to the family Cyperaceae and the genus Cyperus. It has three ranked basal leaves with triangular stems. The seedhead is yellowish-brown to purple to reddish-brown with whitish tubers which may be round to oblong and may or may contain hair depending on the species. Nutsedge reproduce mainly by tubers which are edible (Colvin et al., 1992). Nutsedge is an herbaceous perennial weed that is found 2 throughout most of the world (Troxler et al., 2003). This C 4 perennial weed is one of the world?s most problematic weed species (Earl et al., 2004). Nutsedge?s wide distribution and aggressiveness are partly due to its prolific vegetative reproduction by tubers and rhizomes (Vencill et al., 1995). Due to the longevity and the prolific production of these tubers, Cyperus species are major problem in the southeastern United States (Troxler et al., 2003). In 1997, the Southern Weed Science Society published a survey by Webster and Coble which stated that yellow nutsedge (Cyperus esculentus) and purple nutsedge (Cyperus rotundus) are among the three most problematic weeds in all crops everywhere in the United States due to the fact that they are so well established and difficult to control (Warren et al., 1999). These nutsedge species may also serve as an alternate host for some plant parasitic nematodes (Vencill et al., 1995). Weed competition from nutsedge can reduce crop yields and quality substantially. It has been documented that nutsedge can reduce yields in some agronomic crops by 79 to 87 % (Earl et al., 2004). Even plastic mulch is ineffective in controlling nutsedge, because nutsedge can easily puncture the plastic mulch and compete with the crops (Branenberger et al., 2005). Sulfonylurea (SU) herbicides are generally characterized by their comparatively low application rates, insignificantly adverse environmental effects, and high crop selectivity (Burker et al., 2004). The mode of action of sulfonylurea is characterized by the inhibition of the synthesis of certain branched-chain amino acids like valine, leucine, and isoleucine. The first target enzyme of sulfonylurea is acetolactate synthase (ALS) (Burker et al., 2004). Sulfonylureas (SU) are a rapidly growing class of herbicides. Sulfonylurea was first produced in the 1970?s and then introduced to farmers in 1982. The first SU, 3 chlorosulfuron, was produced in 1975 (Flogel, 1998). It was intended for use as an insecticide on spider mites. Then in 1978 it was patented as an herbicide after testing revealed that it was detrimental to some plants. In 1982 it was marketed for farmers as ?Glean.? Between 1994 and 1996, on average, 89.8 kg of SU were applied in Vermont alone. SU have also been configured as pharmaceuticals in order to treat some forms of diabetes (Flogel, 1998). SU are 100 times more lethal in weed control than herbicides used before 1982 (Flogel, 1998). SU are used to selectively control perennial sedges, such as yellow and purple nutsedge, kyllingas, and a selection of broadleaf weeds in horticultural and agronomic crops (Burker et al., 2004). These herbicides are effective on weeds that previously had limited control measures available. They have short persistence in soil, and can be used in many different situations of weed control as a selective herbicide (Askew et al., 2004). Because of SU ability to control weeds in these different situations with little to no environmental repercussions, this makes it such invaluable component of weed management (Askew et al., 2004). Recently SU such as halosulfuron have been registered for use on vegetables such as tomatoes and cucurbits (Burker et al., 2004). Tomatoes have demonstrated excellent tolerance to rates of halosulfuron. Conversely, peppers which are related to tomatoes are very susceptible to SU. Tolerance to SU has been explained in part to limited absorption and rapid metabolism (Troxler et al., 2003). One of the most significant problems with sulfonylureas is weed resistance. This has been a problem in as many as 27 weed species worldwide. Resistance can develop rapidly when SU are used continuously for as few as four to five years (Askew et al. 4 2004). This can be prevented by rotation of SU with a herbicide with a different mode of action. A tank mix of sulfonylurea and a herbicide with a different mode of action works well in the suppression of resistance. MSMA (monosodiummethanearsonate), metolachlor, and carfentrazone are effective herbicides that tank mix well with SU and do not change its overall effectiveness (Askew et al., 2004). Halosulfuron is in the sulfonylurea class of herbicides which are all acetolactate synthase inhibitors (ALS). Halosulfuron is produced by Gowan and is labeled as Sandea. Halosulfuron is a systemic herbicide (Branenberger et al., 2005). Due to this fact, it may be applied as a preemergence (PRE) or postemergence (POST) herbicide in many situations (McElroy et al., 2004). Halosulfuron has PRE and POST activity on yellow nutsedge and preemergent activity on spiny amaranth (Amaranth spinosu) and ground cherry (Physalis angulata). Halosulfuron is now being used for weed control in vegetable crops (Branenberger et al., 2005). Halosulfuron (Sandea) is registered in many horticultural crops including the cucurbits (Citrullus lantus, Cucumis sativus, Cucumis melo, and Cucurbita pepo) and tomatoes (Lycopersicon esculentum). Trifloxysulfuron is a newer SU which has POST activity and is produced by Syngenta Crop Protection Inc. and labeled as Envoke. Trifloxysulfuron was originally developed for a wide range of broadleaf, sedges, and grass weed control (Branson et al., 2005). Studies proved that trifloxysulfuron has activity on sicklepod, pitted and ivyleaf morningglory, purple and yellow nutsedge, redroot pigweed, lambsquarter, Florida beggarweed, seedling johnsongrass, coffee senna, and hemp sesbania (Branson et al., 2005). Trifloxysulfuron is commonly used as a major component for weed control in turfgrass and is now being studied for weed control in other agronomic and horticultural 5 crops. Trifloxysulfuron is labeled for tomato transplants, cotton, and sugarcane (Syngenta 2005a). S-metolachlor is in the chloroacetamide class of herbicides (Altland et al., 2003). S-metolachlor is produced by Syngenta Crop Protection Inc. and is labeled as Dual Magnum. S-metolachlor is a biosynthesis inhibitor which has a multiple-site, nonspecific mode of action. S-metolachlor is mostly absorbed by emerging roots and shoots and is translocated upward throughout the weed (Syngenta, 2005b). S-metolachlor has been used as a PRE and POST control in agriculture since 1952 (Feigenbrugel et al., 2004). It has been labeled to control annual grasses, yellow nutsedge, and broadleaf weeds in many different crops such as corn, peanuts, cotton, soybeans, tomatoes, potatoes, sugar beets, forage and grain sorghum, safflower, sunflowers, and pod crops (Syngenta, 2005b). The ability of S-metolachlor to control sedges as been established in other crops (Grichar, 1992; Obrigawitch et al., 1980), however in tomato plasticulture little has been published on the use of S- metolachlor alone. Santos et al. (2006a) and Gilreath and Santos (2004b) have published results of combining S-metolachlor with methyl bromide (Mbr) replacements such 1,3-dichloorpropene plus chloropicrin. In 1993 (Gaynor et al.), a study was also produced in which S-metolachlor was combined with trifluralin and metribuzin and applied preplant to determine the best application rates and methods for weed control in tomatoes. Methyl bromide (MBr) has been used since the early 1900s and is a vital component of pest management in many large scale commercial vegetables crops (Webster et al., 2005b). MBr successfully controls insect, soil borne pathogens, and many weed species. About 85% of MBr applications were used in the U.S. as a preplant soil 6 fumigant (Webster et al., 2005b). In agreement with the United States Clean Air Act and provisions of the Montreal Protocol Agreement, MBr has now been slated for removal from all agriculture applications because it is considered an environmental concern (Gilreath and Santos, 2004a). It has been found that MBr is a significant ozone depleting agent. Now with MBr scheduled to be off the market there is a significant challenge for producers to control pests that were previously suppressed by MBr (Webster et al., 2005b). Chemicals like dazomet, dichloropropene, chloropicrin, metam-sodium, and methyl iodine are being investigated and used as MBr substitutes. Even ozone gas, along with steam and soil solarization, may be used as other substitutes (Ames et al., 2003). Tomato production Tomatoes (Lycopersicon esculentum Mill.) are in the Solanaceae family. Members of this family include: nightshade, bell peppers, hot peppers, Irish potatoes, and eggplants (Kemble et al., 2004b). Tomatoes are an annual crop in Alabama grown for its fruit which is berry. They may be determinate or indeterminate. Tomatoes have strongly scented alternately compound leaves that are deeply pinnately lobed. Tomatoes have yellow perfect flowers. Tomatoes are native to the tropical regions of South America. In the seventeenth century the Spanish collected and cultivated tomatoes as they explored these regions (Kemble et al., 2004b). People first thought that tomatoes were poisonous because they were so closely related to nightshades. It was not until the eighteenth century when tomatoes established popularity in Europe (Kemble et al., 2004b). Tomatoes are one of the most valuable and commonly cultivated crops in the world (Gilreath and Santos, 2005). Today, the United States grows and produces more fresh market tomatoes than any other country in the world (Kemble et al., 2004b). 7 Usually, Alabama is ranked twelfth behind California and Florida as some of the leaders of fresh market tomatoes production in the U.S. (Kemble et al., 2004b). In 1998, Florida alone produced more than 600 million dollars worth of fresh market tomatoes, which was about 30 % of U.S. production (Gilreath and Santos, 2005). Tomatoes are warm season crops that are commonly transplanted. They prefer a well drained, sandy loam to a clay loam soil with pH of about 6.0 to 6.8. Tomatoes are heavy feeders and require between 168 to 202 kg/ha of nitrogen (N) and 224 to 280 kg of phosphorous (P 2 O 5) and potash (K 2 O) per ha (Kemble et al., 2004b). About 30 to 50% of the recommend N and K 2 O and 100% of P 2 O 5 are usually incorporated into the soil before planting. The remaining amount is then applied through the irrigation lines. Tomatoes are generally planted on raised beds that are typically covered with polyethylene plastic mulch. These raised beds are about 15 cm high and roughly 74 to 91 cm wide. Polyethylene mulch is used to increases soil temperatures which in return accelerates the plants growth and development. Plastic mulch also conserves soil moisture and may lessen common problems like fruit rotting due to the fruit laying on the ground, soil crusting and compaction, fertilizer leaching, and competition from other weeds. Various colored plastic mulches are commonly used depending on the season, black plastic in the spring and white plastic for summer and fall plantings (Kemble et al., 2004b). Due to the fact that tomatoes are 85 to 95% water, they need between one to four cm of water per week or approximately 666,468 L/ha/day. Due to this fact, drip irrigation is generally used underneath the plastic mulch in most commercial tomato production in the U.S. (Kemble et al., 2004b). Using drip irrigation under plastic mulch enables tomatoes to produce approximately 42,038 to 56,050 kg/ha. 8 There are two options frequently used when it comes to using drip irrigation in fresh market production, drip tape and in-line tubing. Tomato transplants are planted with a spacing of 46 to 61 cm apart with a row spacing of 1.2 to 1.8 m (Kemble et al., 2004b). Tomatoes must be staked in order to have a successful production and harvest. Staking tomatoes improves fruit quality and yield by keeping the fruit off of the ground. In return this helps make harvest slightly easier too. In the practice of staking commercial tomatoes a series of wooden stakes, 1.2 to 1.5 m long by six cm square, and are placed every other tomato plant and then are driven in the ground about 20 to 30.5 cm. Then tomato twine is used (about 34 kg/ha) by tying off to the stake 20 to 25 cm above the soil and then the twine is run down one side of the stake and plant, wrapping the twine around each individual stake, until the end of the row is reached. Then it is duplicated the same way down the other side of the row. This is usually done up to three times in one season depending on the plant (Kemble et al., 2004b). It is common practice to prune tomato plants in commercial applications. Pruning helps sustain equilibrium between vegetative and reproductive development. Pruning will produce smaller vines with larger fruits that will mature earlier. All suckers are removed up to the one directly beneath the first flower cluster (Kemble et al., 2004b). There are several physiological disorders that may arise in the production of fresh market tomatoes. Blossom-end rot (BER) is a physiological disorder that occurs when there is a calcium deficiency within the plant or soil. BER is easily identified by brown, leathery rotted area on or near the blossom end of the fruit. Blossom drop is another disorder that is usually caused by daytime temperature that exceeds 29 0 C with night temperatures above 22 0 C (Kemble et al., 2004b). Then there is puffiness which is caused 9 when there is an imbalance between the nitrogen to potassium ratio. Symptoms of this disorder consist of uneven fruit with hollow cavities. In this disorder the fruit just does not produce the locular gels that fill these cavities (Kemble et al., 2004b). An additional physiological problem is catfacing which has been traced to boron deficiencies. Catfacing is where the fruit puckers up or forms unusual shapes. Another physiological disorder is gray wall. Gray wall takes place when there are combinations of unbalanced nitrogen to potassium ratio, low pH, and/or poorly drained soils. Fruit cracks can be another problem in tomato production. There are two types of cracking that occurs in tomatoes, radial and concentric. Radial cracking, the most common, occurs after periods of hot dry weather followed by a profound rainy period. Concentric cracking, which usually begins on green fruits, are cracks that are produced by intense exposure to the sunlight (Kemble et al., 2004b). Sunscald can also be a problem in tomatoes, it occurs like concentric cracking from intense exposure to the sun. This disorder is characterized by the development of dark green shoulders on immature fruits which turn yellow in color as the fruit ripens (Kemble et al., 2004b). There are basically three types of tomatoes harvested in commercial tomato production, mature greens, pinks/light reds, and vine ripe. Mature greens are harvested for shipping long distances. These fruits are harvested at the mature green stage. Pinks/ light reds are usually harvested for sale at local pink markets. These fruits are usually harvested at the breaker stage of immaturity where they are slightly more mature than mature green but not as mature as vine ripe tomatoes. They are harvested when they are about 60 to 90 percent red in color. Vine ripe tomatoes are harvested for local markets, usually at the breaker stage of maturity (Kemble et al., 2004b). 10 Tomato production in the Southeast is hampered by several species of broadleaf weeds, and plastic mulch is an effective component in their control (Chase et al., 1998; Patterson, 1998). However, many weed species are capable of establishing themselves in the holes that are punches in the mulch through which tomato seedlings are transplanted. In addition, both yellow (Cyperus esculentus) and purple nutsedge (Cyperus rotundus) are capable of piercing plastic mulches (Webster and Culpepper, 2005; Johnson and Mullinex, 2002). Ideally plastic mulch can serve for several cropping cycles. However nutsedge piercing reduces mulch benefits and accelerates its degradation. Removal, disposal and replacement of deteriorating mulch can be a significant cost (Preece and Read, 2005). Soil fumigation prior to the laying of the plastic mulch has been an effective means of weed control. However, the effective fumigant methyl bromide (Mbr) is being cancelled. Thus there exists the need to find alternative methods for nutsedge control in plastic culture tomato, as well as other vegetables subject to similar culture. Since both S-metolachlor and halosulfuron have soil-based nutsedge activity, my first objective was to determine if any combinations may be more effective than either material applied alone in a field study that excluded any confounding factors due the presence of a crop. My second objective was to evaluate selected herbicide treatments in the field utilizing plastic mulch supplemented with S-metolachlor and/or halosulfuron as based upon previous results described herein. My third objective was to evaluate injecting selected herbicide combinations (S-metolachlor and/or halosulfuron/trifloxysulfuron) as a labor saving application compared to conventional PRE-applied applications. 11 LITERATURE CITED Abdul-Baki, A.A., J.R. Teasedale, D.J. Chitwood, and R.N. Huettel. 1993. Effect of mulches on growth and yields of muskmelon. Proc. Natl. Agr. Plastics Cong. 24:303-308. Ahrens, B. http://www.wssa.net/herb&control/chemframe.html. Date accessed 6-31-06. Altland, J. E., C. H. Gilliam, and G. 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Brown D. and J. Masiunas. 2002. Evaluation of herbicides for pumpkin ( cucurbita spp). Weed Tech. 16:282-292. 12 Brown, J.E., and C. Channell-Butcher. 1999. Effect of three row covers and black plastic mulch on the growth and yield of ?Clemson Spineless? okra. J. of Veg. Crop Prod. 5(2):67-71. Burker, R. S. III., B. Rathinasabapathi, G. MacDonald, and S.M. Olson. 2004. Physiological basis for differential tolerance of tomato and pepper to rimsulfuron and halosulfuron: site of action study. Weed Sci 52:201-205. Chase, C.A., T.R. Sinclair, D.G. Shilling, J.P. Gilbreath, and S.J. Locascio.1998.Light effects on rhizome morohogenesis in nutsedges (Cyperus spp.) implications for control by soil solarization. Weed Sci. 46:575-580. Colvin, D. L., R. Dickens, J. W. Everest, D. Hall, and L.B. McCarty. 1992. Weeds of southern turfgrasses. Alabama Cooperative Extension System Alabama A&M and Auburn Universities. P. 14, 19. Derr, J.F.,T.R. Sinclair, R.S. Chandran, and W.D. Ward. 1996. Preemergence and postemergence yellow nutsedge (Cyperus esculentus) control with MON12000 in nursery crops. Weed Tech. 10:95-99. Drenovsky, R. E., R. A. Duncan, and K. M. Scow. 2005. Soil sterilization and organic carbon, but not microbial inoculants, change microbial communities in replanted peach orchards. California Agriculture 59:176-181. Durigan, J. C., P.C. Timossi, and G. J. Leite. 2004.Chemical control of Cyperus rotundus with and without sugarcane straw cover. Planta Daninha 22:127-135. Earl, H. J., J. A. Ferrell, W. K. Vencill, M. W.Van Iersel, and M. A. Czarnota. 2004. Effects of three herbicides on whole plant carbon fixation and water use by yellow nutsedge (Cyperus esculentus). Weed Sci. 52:213-216. 13 Eizenberg, H., Y. Goldwasser, G. Achdary, and J. Hershenhorn. 2003. The potential of sulfosulfuron to control troublesome weeds in tomatoes. Weed Techno. 17:133- 137. Fennimore, S. A. and S. J. Richard. 1999. Screening of low rate herbicides in vegetable crops. Moscow, ID: West. Soc. Weed Sci. Res. Prog. Rep. 44-46. Ferrell, J. A., H. J. Earl, and W. K. Vencill. 2004. Duration of yellow nutsedge (Cyperus esculentus) competitiveness after herbicide treatment. Weed Sci. 51:24-27. Fiegenbruge, V., S. Le Calve, and P. Mirabel. 2004. Temperature dependence of Henry?s law constants of metolachlor and diazinon. Chemosphere 57:319-327. Farm Chemicals Handbook Global Guide to Crop Protection. 2002. MeisterPRO information resources. 88:219, 272-273. Farm Chemicals Handbook Global Guide to Crop Protection. 2003. MeisterPRO information resources. 88:472. Flogel, M. 1998. Backgrounder on sulfonylurea herbicides. Vermont Public Interest Research Group. Web page: www.vpirg.org . Date accessed 6-31-06. Gad, S.C., and C.S. Weil.1989. Statistics for toxicologist. A.W. Hayes,ed. Principles and Methods of Toxicology. New York, NY: Raven Press. Pp. 435-484. Gaynor, J.D., A.S. Hamill, and D.C. MacTavish. 1993. Efficacy, fruit residues, and soil dissipation of the herbicide metolachlor in processing tomato. J. Amer. Soc. Hort. Sci. 118(1):68-72. Gerber, J.M., J.E. Brown, and W.E. splittstoesser. 1983. Economic evaluation of plastic mulch and row tunnels for use in muskmelon production. Proc. Natl. Agr. Plastics Cong. 17:46-50. 14 Gilreath, J. P. and B. M. Santos. 2005. Efficacy of 1, 3-dichloroproene plus Chloropicrin in combinations with herbicides on purple nutsedge (Cyperus rotundus) control in tomatoes. Weed Tech. 19:137-140. Gilreath, J. P. and B. M. Santos. 2004a. Efficacy of methyl bromide alternatives on purple nutsedge control (Cyperus rotundus) in tomatoes and peppers. Weed Tech. 18:141-145. Gilreath, J. P. and B. M. Santos. 2004b. Herbicide dose and incorporation depth in combination with 1,3-dichloroprpene plus chloropicrin for Cyperus rotundus control in tomato and pepper. Crop Protection. 23:205-210. Grichar, W.J. 1992. Yellow nutsedge (Cyperus esculentus) control in peanuts (Arachis hypogea). Weed Tech. 6:108-112. Haar, M. J., S. A. Fennimore, M. E. McGiffen, W. T. Lanini, and C. E. Bell. 2002. Evaluation of preemergence herbicides in vegetable crops. HortTechnology 12:95-99. Herbicide handbook of the weed science society of America.1983.5 th edition. P. 315-316. Herbicide handbook of the weed science society of America. 2002. 8 th edition. P. 236. Ibarra, L., J. Flores, and J.C. Diaz-Perez. 2001. Growth and yield of muskmelon in response to plastic mulch row covers. Scientia Horticulturea 87:139-145. Johnson, W. C. III and B. G. Mullinix Jr. 2002. Weed management in watermelon (Citrullus lanatus) and cantaloupe (cucumis melo) transplanted on polyethylene- covered seedbeds. Weed Tech. 16:860-866. 15 Kemble, J.M., M.G Patterson, and J.W Everest. 2004a. Nutsedge control in commercial vegetables. Alabama Cooperative Extension System Alabama A&M and Auburn Universities. ANR-1073. Kemble, J.M., T.W. Tyson, and L.M. Curtis. 2004b. Guide to commercial staked tomato production in Alabama. Alabama Cooperative Extension System Alabama A&M and Auburn Universities. ANR-1156. Khan, V.A., C. Stevens, C. Stevens III, M.A. Wilson, J.E. Brown, and D.J. Collins. 1999. The effect of agriplastics mulches on growth response, foliage and root endophytic and rhizoshere bacteria of ? Crimson Sweet? watermelon. Proc. Natl. Agr. Plastics Cong. 28:39-43. Koger, C. H., A. J. Price, and K. N. Reddy. 2005. Weed control and cotton response to combinations of glyphosate and trifloxysulfuron. Weed Tech. 19:113-121. Littell, R.C., G.A. Milliken, W.W. Stroup, and R.D. Wolfinger. 1996. SAS System for Mixed Models. SAS Institute Inc., Cary, NC. McElroy, S. J., F. H. Yelverton, I. C. Burke, and J. W. Wilcut. 2004. Absorption, translocation, and metabolism of halosulfuron and trifloxysulfuron in green kyllinga (Kyllinga brevifolia) and false-green kyllinga (K. gracillima). Weed sci 52:704-710. Mullen, R. J., J. Caprile, T. C. Viss, M. Rego, D. Brunmeier, C. Cancilla, and C.J. Rivara. 2001. New weed management research in processing tomatoes. Acta Hort. 542:39-45. 16 Nelson, K. A., and K. A. Renner. 2002. Yellow nutsedge (Cyperus esculentus) control and tuber production with glyphosate and ALS-inhibiting herbicides. Weed Tech. 16:512-519. Obrigawitch, T., J.R. Gipson, and J.R. Abernathy. 1980 Activity of metolachlor on nutsedge. Proc. of the 33 rd annual meeting of the S. Weed Soc. P. 225. Patterson, D.T.1998. Suppression of purple nutsedge (Cyperus rotundus) with polyethylene film mulch. Weed Tech. 12:275-280. Preece, J. E. and P. E. Read. 2005. The biology of horticulture 2 nd edition. John Wiey & sons, Inc. Mulches. P. 281-291. Reed, G.L., G.H. Clough, and D.E. Hemphill. 1989. The effect of slit, perforated, and net row covers on soil and crop temperatures and periodicity of muskmelon yield. Proc. Natl. Agr. Plastics Cong. 21:116-122. Sanders, D.C., J.D. Cure, and J.R. Schuletheis. 1999. Yield response of watermelon to planting density, planting pattern, and polyethylene mulch. HortTech. 34(7):1221- 1223. Santos, B. M., J. P. Gilreath, T. M. Motis, J.W. Noling, J.P. Jones, and J.A. Norton 2006a. Comparing methyl bromide alternatives for soilborne disease, nematodes and weed management in fresh market tomato. Crop Protection. 25:690-695. Santos, B. M., J. P. Gilreath, and T. M. Motis. 2006b. Impact of chloropicrin on nutsedge emergence through polyethylene mulch. HortTech. 16:30-32. Schales, F.D., and R. Sheldrake Jr. 1965. Mulch effects on soil conditions and muskmelon response. J. Amer. Soc. Hort. Sci. 88:425-430. 17 Seefeldt, S.S., J.E. Jensen, and E.P. Fuerst.1995. Log-logistic analysis of herbicide dose- response relationships. Weed Tech. 9:218-227. Singh, S., and M. Singh. 2004. Effect of growth stage on trifloxysulfuron and glyphosate efficacy in twelve weed species of citrus groves. Weed Tech. 18:1031-1036. Stall, W. M., and J. Gilreath. 2005. Weed control in tomato. University of Florida IFAS Extension. HS200. Syngenta. 2005a. Syngenta Crop Protection Inc. Webpage: http://www.syngentacropprotection - us.com/prod/herbicide/Envoke/index.asp?nav =labels Date accessed 6-31-06. Syngenta. 2005b. Syngenta Crop Protection Inc. Webpage: http://www.syngentacropprotection-us.com/prod/herbicide/Dualmagnum/. Date accessed 6-31-06. Thomson, W.T. 2002. Agriculture Chemicals Book II Herbicides. Thomson Publications 51-52, 144- 145. Troxler, S., J.W. Wilcut, W. D. Smith, and J.Burton. 2003. Absorption, translocation, and metabolism of foliar-applied CGA-362622 in purple and yellow nutsedge (Cyperus rotundus and C. esculentus). Weed Sci. 51:13-18. Unknown. Sulfonylureas. www.hill-laboratories.com/Files/PDFs/8728v1View.Pdf. Sulfonylureas. Vencill, W. K., J. S. Richburge, III, J. W. Wilcut, and L. R. Hawf. 1995. Effect of MON- 12037 on purple (Cyperus rotundus) and yellow (Cyperus esculentus) nutsedge. Weed Tech. 9:148-152. 18 Warren, L. S. JR., and H. D. Coble. 1999. Managing purple nutsedge (Cyperus rotundus) populations utilizing herbicide strategies and crop rotation sequences. Weed Tech. 13:494-503. Webster, T. M. 2005a. Mulch type affects growth and tuber production of yellow nutsedge (Cyperus esculentus) and purple nutsedge (Cyperus rotundus). Weed Sci. 53:834-838. Webster, T. M. 2005b. Patch expansion of purple nutsedge (Cyperus rotundus) and yellow nutsedge (Cyperus esculentus) with and without polyethylene mulch. Weed Sci. 53:839-845. Webster, T., and A. Culpepper. 2005a. Eggplant tolerance to halosulfuron applied through drip irrigation. Hortscience. 40:1796-1800. Webster, T. M., and A. S. Culpepper. 2005b. Halosulfuron has a variable effect on cucurbit growth and yield. Hortscience 43:707-710. Webster, T. M., A. S. Culpepper, and W. C. Johnson III. 2003. Response of squash and cucumber cultivars to halosulfuron. Weed Tech. 17:173-176. Webster, T. M. and H. D. Coble. 1997a. Changes in the weed species composition of the southern United States: 1974 to 1995. Weed Tech. 11:308-317. Zhang, J., A. S. Hamill, and S. Weaver. 1995. Antagonism and synergism between herbicides trends from previous studies. Weed Tech. 9:86-90. 19 CHAPTER 2 EVALUATION OF COMBINING SULFONYLUREAS AND S-METOLACHLOR TO CONTROL NUTSEDGE UNDERNEATH POLYETHELENE MULCH Collin W. Adcock, Wheeler G. Foshee III, Glenn R. Wehtje, and Charles H. Gilliam Abstract: Field studies were conducted in the summer of 2005 at Auburn University?s E.V. Smith Research Center and Wiregrass Research and Extension Center in Alabama. In this study there were a total of 24 treatments, factorial arranged in a randomized complete block with six levels of S-metolachlor (0.0, 0.28, 0.56, 0.84, 1.12, and 1.40 kg a.i. /ha) and four levels of halosulfuron (0, 10, 20, and 40 g a.i. /ha) applied preemergence (PRE) in a split plot of bareground and plastic mulch. Approximately 30 days after application (DAA), when nutsedge emergence had reached peak populations, numerical puncture data were taken in a ten foot plot area along with nutsedge biomass. In bareground and with plastic mulch, both S-metolachlor and halosulfuron resulted in a rate-dependent reduction in yellow nutsedge foliage. However, neither herbicide applied alone resulted in complete nutsedge control. While the main effects of both herbicides were significant, the interaction was not. Therefore, theses two herbicides are additive and no synergism or antagonism was detected with respect to their ability to control 20 nutsegde. The most effective individual treatments were the highest rate of halosulfuron or S-metolachlor applied at 40 and 140 g/ha, respectively. This treatment reduced yellow nutsedge foliage 73 and 59 percent in bareground and mulched plots, correspondingly. Plastic mulch punctures were reduced 80 percent. Nomenclature: S-metolachlor; sulfonylurea; halosulfuron; trifloxysulfuron; Methyl bromide (MBr); yellow nutsedge (Cyperus esculentus); purple nutsedge (Cyperus rotundus) PRE, Herbigation. Additional index words: halosulfuron, trifloxysulfuron, sulfonylurea, S-Metolachlor, herbicide combinations, polyethylene Abbreviations: ALS, acetolactate synthase inhibitors; PRE, preemergence; DAA, days after application INTRODUCTION Nutsedge is a major weed problem in various horticultural and agronomic crops all over the world (Warren and Coble, 1999). Nutsedge?s wide distribution and aggressiveness is in part to its prolific vegetative reproduction by tubers and rhizomes (Vencill et al., 1995). Due to the longevity and prolific production of these tubers, Cyperus species are an extremely difficult problem in the southeastern United States (Troxler et al., 2003). Weed competition from nutsedge can reduce crop yields and quality substantially. It has been documented that nutsedge can reduce yields in some agronomic crops by 79 to 87 % (Earl et al., 2004). Cyperus esculentus (yellow nutsedge) is widespread in most areas where commercial vegetable crops are grown. The only 21 effective means of control for nutsedge is with the use of herbicides, but there limited number of herbicides labeled for use in vegetables (Kemble et al., 2004a). Tomato production in the Southeast is hampered by several species of broadleaf weeds, and plastic mulch is an effective component in their control (Chase et al,. 1998; Patterson, 1998). However, many weed species are capable of establishing themselves in the holes that are punches in the mulch through which tomato seedlings are transplanted. In addition, both yellow (Cyperus esculentus) and purple nutsedge (Cyperus rotundus) are capable of piercing plastic mulches (Webster and Culpepper, 2005; Johnson and Mullinex, 2002). Ideally plastic mulch can serve for several cropping cycles. However nutsedge piercing reduces mulch benefits and accelerates its degradation. Removal, disposal and replacement of deteriorating mulch can be a significant cost (Preece and Read, 2005). Soil fumigation prior to the laying of the plastic mulch has been an effective means of weed control. However, the effective fumigant methyl bromide (Mbr), is being cancelled. Thus there exists the need to find alternative methods for nutsedge control in plastic culture tomato, as well as other vegetables subject to similar culture. Halosulfuron is in the sulfonylurea class of herbicides which are all acetolactate synthase inhibitors (ALS). This class of herbicides is commonly used to control purple nutsedge (C. rotundus), yellow nutsedge (C. esculentus), and select broadleaf weed species in agronomic and horticultural crops. Halosulfuron is a systemic herbicide (Branenberger et al., 2005), and may be applied as a PRE or POST application in many situations (McElroy et al., 2004). Halosulfuron is now being used for weed control in 22 vegetable crops (Branenberger et al., 2005), whereas it was previously used only in turfgrass systems (McElroy et al., 2004). S-metolachlor is in the chloroacetamide class of herbicides (Altland et al., 2003) labeled on tomatoes (Syngenta, 2005a). S-metolachlor is a biosynthesis inhibitor which has a multiple-site, nonspecific mode of action. S-metolachlor is mostly absorbed by emerging roots and shoots and is translocated upward throughout the weed (Syngenta, 2005a). S-metolachlor has been used as a PRE and POST herbicide in agriculture since 1952 (Fiegenbruge et al., 2004). S-metolachlor has been labeled to control annual grasses, yellow nutsedge, and broadleaf weeds in many different crops such as corn, peanuts, cotton, soybeans, tomatoes, potatoes, sugar beets, forage and grain sorghum, safflower, sunflowers, and pod crops (Syngenta, 2005a). Therefore, the objective of this first study was to evaluate PRE-applied halosulfuron, as well as POST-applied where contact is limited to foliar-only contact over a series or rates with the intent of determining the exact rate required for yellow nutsedge control. MATERIALS AND METHODS Field studies were conducted in May of 2005 at the Auburn University?s E.V. Smith Research Center (EVS) and Wiregrass Research and Extension Center (WREC) where the soil types were a Dothan sandy loam with a pH of 5.8-6.2. At both locations the soil was prepared and shaped into eight parallel beds. Four rows were randomly selected to receive plastic mulch after treatment applications. In this study there were a total of 24 treatments, factorial arranged in a complete randomized block split block design with six levels of S-metolachlor (0.0, 0.28, 0.56, 0.84, 1.12, and 1.40 kg a.i. /ha) 23 and four levels of halosulfuron (0, 10, 20, and 40 g a.i. /ha) applied preemergence in a split plot of bareground and plastic mulch. Each plot was 2.03 m long and consisted of pre-formed beds with polyethylene mulch accompanied with a bareground. Treatments were replicated four times. Plots with heavy infestations of yellow nutsedge were chosen. Treatments were applied with a CO 2 back-pack sprayer set to deliver 140 liters per hectare (L/ha). The sprayer was equipped with three (11002) spaced 0.67 m apart on the boom. After herbicide treatments were applied plastic mulch was applied to randomly selected rows. No crop was planted since the objective was to evaluate nutsedge control along with nutsedge piercing ability of the mulch. Approximately 30 days after application (DAA) when nutsedge emergence had reached peak populations, numerical puncture data along with nutsedge biomass was taken in a 1.5 m plot area. Statistical analysis was conducted using a general linear model with the PROC GLM procedure of SAS Version 9.1 (SAS Institute, Cary, NC) for fresh weight data. RESULTS AND DISCUSSION In bareground and with plastic mulch, both S-metolachlor and halosulfuron resulted in a rate-dependent reduction in yellow nutsedge foliage (Table 1). However, neither herbicide applied alone resulted in adequate nutsedge control. While the main effects of both herbicides were significant, the interaction was not. Therefore, these two herbicides are additive and no synergism or antagonism was detected with respect to their ability to control nutsedge. The most effective individual treatment was a combination of halosulfuron and S-metolachlor applied at 40 and 140 g/ha, respectively. This treatment reduced nutsedge foliage 73 and 59 percent in bareground and mulched plots, 24 correspondingly (data not shown) Plastic mulch punctures were reduced 80 percent (data not shown). Results from this study indicated that no synergism or antagonism was detected with the combinations of halosulfuron and S-metolachlor. The highest rate of either herbicide applied PRE gave the best control of yellow nutsedge punctures, however, no treatment protected the plastic for potential multi-cropping. LITERATURE CITED Altland, J. E., C. H. Gilliam, and G. Wehtjie. 2003. Weed control in field nurseries. HortTech. 13:9-14. Branenberger, L. P., R.E. Talbert, R. P.Wiedenfeld, J. W. Shrefler, C. L. Webber III, and M. S. Malik. 2005. Effects of halosulfuron on weed control in commercial honeydew crops. Weed Tech. 19:346-250. Branson, J. W., K.L. Smith, and J. L. Barrentine. 2005. Comparison of trifloxysulfuron and pyrithiobac in glyphosate-resistant and bromoxynil-resistant cotton. Weed Tech. 19:404-410. Chase, C.A., T. R. Sinclair, D. G. Shilling, J. P. Gilreath, and S. J. Locascio. 1998. Light effects on rhizome morphogenesis in nutsedge (Cyperus spp.) Implications for control by soil solarization. Weed Sci. 46:575-580. Earl, H. J., J. A. Ferrell, W. K. Vencill, M. W.Van Iersel, and M. A. Czarnota. 2004. Effects of three herbicides on whole plant carbon fixation and water use by yellow nutsedge (Cyperus esculentus). Weed Sci. 52:213-216. 25 Fiegenbruge, V., S. Le Calve, and P. Mirabel. 2004. Temperature dependence of Henry?s law constants of metolachlor and diazinon. Chemosphere 57:319-327. Johnson III, W. C., and B. G. Mullinix Jr. Weed management in watermelon (Citrullus lanatus) and cantaloupe (Cucumis melo) transplanted on polyethylene-covered seedbeds. Weed Tech. 860-866. Kemble, J.M., M.G Patterson, and J.W Everest. 2004a. Nutsedge control in commercial vegetables. Alabama Cooperative Extension System Alabama A&M and Auburn Universities. ANR-1073. Kemble, J.M., T.W. Tyson, and L.M. Curtis. 2004b. Guide to commercial staked tomato production in Alabama. Alabama Cooperative Extension System Alabama A&M and Auburn Universities. ANR-1156. Littell, R.C., G.A. Milliken, W.W. Stroup, and R.D. Wolfinger. 1996. SAS System for Mixed Models. SAS Institute Inc., Cary, NC. McElroy, S. J., F. H. Yelverton, I. C. Burke, and J. W. Wilcut. 2004. Absorption, translocation, and metabolism of halosulfuron and trifloxysulfuron in green kyllinga (Kyllinga brevifolia) and false-green kyllinga (K. gracillima). Weed sci 52:704-710. Patterson, D. T. 1998. Suppression of purple nutsedge (Cyperus rotundus) with polyethylene film mulch. Weed Tech. 12: 275-280. Preece, J.E. and P.E. Read. 2005. The biology of horticulture. 2 nd Edition. John Wiley & Sons, Inc., Mulches. P. 281-291. 26 Syngenta. 2005a. Syngenta Crop Protection Inc. Webpage: http://www.syngentacropprotection-us.com/prod/herbicide/Dualmagnum/. Date accessed 5/10/06. Troxler, S., J.W. Wilcut, W. D. Smith, and J.Burton. 2003. Absorption, translocation, and metabolism of foliar-applied CGA-362622 in purple and yellow nutsedge (Cyperus rotundus and C. esculentus). Weed Sci. 51:13-18. Vencill, W. K., J. S. Richburge, III, J. W. Wilcut, and L. R. Hawf. 1995. Effect of MON- 12037 on purple (Cyperus rotundus) and yellow (Cyperus esculentus) nutsedge. Weed Tech. 9:148-152. Warren, L. S. JR., and H. D. Coble. 1999. Managing purple nutsedge (Cyperus rotundus) populations utilizing herbicide strategies and crop rotation sequences. Weed Tech. 13:494-503. Webster, T. M., and A. S. Culpepper. 2005. Halosulfuron has a variable effect on cucurbit growth and yield. Hortscience 43:707-710. 27 Table 1. Main Effects of S-metolachlor and halosulfuron when soil applied as a tank mixture and followed either with or without plastic mulch for the control of yellow nutsedge conducted at E.V. Smith Research Center, Tallassee, Alabama and Wiregrass Research and Extension Center, Headland, Alabama in the summer of 2005. Herbicide Rates % Control Bareground * % Control Plastic Mulch * S-metolachlor (kg a.i./ha) 0 26c 25b 0.28 29c 31b 0.56 31bc 31b 0.84 46a 35b 1.12 43ab 38ab 1.40 56a 51a Halosulfuron (g a.i./ha) 0 28c 24b 10 32bc 30b 20 43ab 42a 40 51a 45a *Means within column that are followed by the same letter are equivalent according to Fisher?s protected LSD (P=0.05) 28 CHAPTER 3 EVALUATION OF S-METOLACHLOR AND HALOSULFURON COMBINATIONS FOR MANAGEMENT OF NUTSEDGE ON TOMATO YIELDS Collin W. Adcock, Wheeler G. Foshee III, Glenn R. Wehtje, and Charles H. Gilliam Abstract: Field studies were conducted in 2006 at the Auburn University?s E.V. Smith Research Center and Chilton County Research and Extension Center in Alabama to determine effects of S-metolachlor and halosulfuron for nutsedge control on tomato yields. This was a randomized complete block design study with a total of six treatments of S-metolachlor (1.40 kg a.i./ha) applied preemergence (PRE), S-metolachlor (1.40 kg a.i./ha) and halosulfuron (40 g a.i./ha) PRE, along with a split applications of S- metolachlor (1.40 kg a.i./ha) PRE followed by halosulfuron (40 g a.i./ha) postemergence (POST), S-metolachlor (1.40 kg a.i./ha) and halosulfuron (20 g a.i./ha) PRE followed by halosulfuron (20 g a.i./ha) POST, a plastic mulch only treatment, and a bareground nontreated control. Yields were affected by plastic mulch, but not any herbicide applications. Tomatoes grown in nontreated bareground treatment had a three-fold decrease in yields compared to any plastic mulch treatment. Furthermore, herbicide treatments did not result in any increase in percent control, number of punctures, number of punctures per square foot of plastic, or biomass of yellow nutsedge. Applied herbicides did not increase tomato 29 yields or provide improved nutsedge control compared to plastic mulch alone. Furthermore, the level of yellow nutsedge pressure in theses two field studies (approximately 1 /0.093 m 2 ) did not decrease yields. No treatments protected plastic mulch from nutsedge piercing. Nomenclature: S-metolachlor; sulfonylurea; halosulfuron;; Methyl bromide (MBr); tomato (Lycopersicon esculentum Mill.); Var Florida 91; yellow nutsedge (Cyperus esculentus L.); purple nutsedge (Cyperus rotundus L.) PRE, POST. Additional index words: sulfonylurea, S-Metolachlor, herbicide combinations, polyethylene mulch. Abbreviations: ALS, acetolactate synthase inhibitors; PRE, preemergence; POST, postemergence; DAA, days after application. INTRODUCTION Nutsedge is a major weed problem in various horticultural and agronomic crops all over the world (Warren and Coble, 1999). Nutsedge?s wide distribution and aggressiveness is in part to its prolific vegetative reproduction by tubers and rhizomes (Vencill et al., 1995). Due to the longevity and prolific production of these tubers, Cyperus species are an extremely difficult problem in the southeastern United States (Troxler et al., 2003). Weed competition from nutsedge can reduce crop yields and quality substantially. It has been documented that nutsedge can reduce yields in some agronomic crops by 79 to 87 % (Earl et al., 2004). Cyperus esculentus (yellow nutsedge) is widespread in most areas where commercial vegetable crops are grown. One of the only effective means of control for nutsedge is with the use of herbicides, but there are a 30 limited number of herbicides labeled for use in vegetables to control nutsedge (Kemble et al., 2004a). Halosulfuron is in the sulfonylurea class of herbicides which are all acetolactate synthase inhibitors (ALS). This class of herbicides is commonly used to control purple nutsedge (C. rotundus), yellow nutsedge (C. esculentus), and select broadleaf weed species in agronomic and horticultural crops. Halosulfuron is a systemic herbicide (Branenberger et al., 2005), and may be applied as a PRE or POST application in many situations (McElroy et al., 2004). Halosulfuron is now being used for weed control in vegetable crops (Branenberger et al., 2005), whereas it was previously used only in turfgrass systems (McElroy et al., 2004). S-metolachlor is in the chloroacetamide class of herbicides (Altland et al., 2003) labeled on tomatoes (Syngenta, 2005a). S-metolachlor is a biosynthesis inhibitor which has a multiple-site, nonspecific mode of action. S- metolachlor is mostly absorbed by emerging roots and shoots and is translocated upward throughout the weed (Syngenta, 2005a). S-metolachlor is in the chloroacetamide class of herbicides (Altland et al., 2003) labeled on tomatoes (Syngenta, 2005a). S-metolachlor is a biosynthesis inhibitor which has a multiple-site, nonspecific mode of action. S-metolachlor is mostly absorbed by emerging roots and shoots and is translocated upward throughout the weed (Syngenta, 2005a). S-metolachlor has been used as a PRE and POST herbicide in agriculture since 1952 (Fiegenbruge et al., 2004). S-metolachlor has been labeled to control annual grasses, yellow nutsedge, and broadleaf weeds in many different crops such as corn, peanuts, cotton, soybeans, tomatoes, potatoes, sugar beets, forage and grain sorghum, safflower, sunflowers, and pod crops (Syngenta, 2005a). The ability of S-metolachlor to control 31 sedges as been established in other crops (Grichar, 1992; Obrigawitch et al., 1980), however in tomato plasticulture little has been published on the use of S- metolachlor alone. Santos et al. (2006) and Gilreath and Santos (2004) have published results of combining S-metolachlor with methyl bromide (Mbr) replacements such 1,3- dichloorpropene plus chloropicrin. In 1993 (Gaynor et al.), a study was also produced in which S-metolachlor was combined with trifluralin and metribuzin and applied preplant to determine the best application rates and methods for weed control in tomatoes. The objective of this study was to evaluate selected herbicide treatments in the field utilizing plastic mulch supplemented with S-metolachlor and/or halosulfuron based upon the results from the previous study evaluating PRE-applied halosulfuron alone. MATERIALS AND METHODS In 2006, field studies were conducted at Auburn Universities E.V. Smith Research Center (EVS) and Chilton County Research and Extension Center (CCRC) in Alabama to determine effects of S-metolachlor and halosulfuron for nutsedge control on tomato yields. Soil types at these both sites were a Dothan sandy loam. EVS had a pH of 5.8 and CCRC had a pH of 5.9. At both locations the soil was prepared and shaped into six parallel beds. This was a randomized complete block design study with a total of six treatments of S-metolachlor (1.40 kg a.i./ha) applied preemergence (PRE), S-metolachlor (1.40 kg a.i./ha) and halosulfuron (40 g a.i./ha) PRE, along with a split applications of S- metolachlor (1.40 kg a.i./A) PRE followed by halosulfuron (40 g a.i./ha) postemergence (POST), S-metolachlor (1.40 kg a.i./ha) and halosulfuron (20 g a.i./ha) PRE followed by halosulfuron (20 g a.i./ha) POST, a plastic mulch only treatment, and then a bareground nontreated control. Plots with heavy nutsedge infestations were chosen. Treatments were 32 applied with a CO 2 back pack sprayer set at 140 Liters per hectare (L/ha). The sprayer was equipped with a four 11002 nozzles spaced at 0.67 m apart on the boom. After herbicide treatments were applied plastic mulch along with drip tape was applied to all rows. Tomato transplants (?Fla 91?) were planted on 45.7 cm spacing and were grown and maintained according to commercial tomato practices (Kemble et al., 2004b). There were 13 tomato transplants per plot at EVS and 18 per plot at CCRC both with 9 m long with a 1.5 m buffer zone on both ends of the plots. After a period of approximately 40 days after planting (DAA), the POST treatments (halosulfuron (40 g a.i./ha and 20 g a.i./ha) were applied. Tomato yields were collected and graded every week throughout the growing season. At the conclusion of the study approximately 112 days after application (DAA) weed biomass was collected in 2.4 m section of every plot. RESULTS AND DISCUSSION Analysis of variance (ANOVA) revealed no treatment differences and no significant interactions between locations; therefore data were pooled. Yields were affected by plastic mulch, but not herbicides. All herbicide treatments had similar total marketable yields, total marketable number of fruit, total nonmarketable number of fruit, and total non marketable weight (Table1). Plastic mulch treatments were similar in total marketable yields, total marketable number, total unmarketable yields, and total unmarketable number (Table 1; Figure 1, 2, 3, and 4). There were no differences for percent control, number of punctures, or number of punctures per square foot for the plastic mulched treatments (Table 2; Figure 5, 6, and 7). Nontreated bareground plots became infested with crabgrass, eclipta, and pigweed in addition to yellow nutsedge. Nontreated bareground plots had the lowest marketable 33 yields, i.e. 3.17 kg/plot, as well as total marketable number (Table 1; Figure 1 and 2). Complete control of all pertinent weed species other than yellow nutsedge was obtained in the plastic mulch alone treatments. However, yellow nutsedge proliferated the nontreated plastic mulch treatment resulting in 132 g/plot of nutsedge and 31 punctures per plot (Table 2 and 3; Figure 6 and 8). This proliferation of yellow nutsedge can likely be attributed to the combined effects of its ability to penetrate plastic mulch and the lack of competition from other weed species. Treatments with only plastic mulch yielded 10,886 g/plot of total marketable tomatoes, which represented a greater than three-fold increase over the comparable bareground treatment (Table 1 and Figure 1). This mulched induced yield increase can be partially attributed to weed control. However, benefits from plastic mulch also include soil moisture conservation and reduction of diseases. S- metolachlor applied PRE alone (i.e. under mulch) neither improved yellow nutsedge control or tomato yield relative to mulch with any other herbicides. The two treatments in which a tank mixture of S-metolachlor and halosulfuron applied PRE were no more effective than S-metolachlor PRE. The most effective treatment with respect to yellow nutsedge suppression and without yield suppression was S-metolachlor PRE followed by halosulfuron POST (Table 3; Figure 8). This treatment had 0.07 kg of nutsedge biomass which was lower than S-metolachlor PRE (Table 3). All other treatments were similar. However, yellow nutsedge biomass and plastic mulch punctures were only reduced 50 and 29 percent compared to plastic mulch alone. This result would possibly render the plastic mulch unsuitable for multiple cropping. Due to a combination of weed control and plastic mulch, tomato yields were increased three-folds. Unfortunately, the plastic mulch was readily penetrated by yellow 34 nutsedge punctures and no PRE-applied treatment was identified that could reduce nutsedge based on mulch penetration. Earlier results from determination of the LD 90 of PRE-applied halosulfuron to germinating nutsedge tubers and from the performance of PRE-applied S-metolachlor and halosulfuron tank mixtures in the non-crop field study, leads to the hypothesis that these tank mixtures should be effective in limiting nutsedge punctures during tomato production. However, results did not support this hypothesis. One possible explanation is the limited soil longevity of these herbicides. The reported soil half life of S-metolachlor is 15 to 25 days (Herbicide Handbook, 1983). The soil half life for halosulfuron is four to 34 days depending on locations and environments (Herbicide Handbook, 2002). Nutsedge punctures were evaluated three to four weeks after application in the no-crop field study. Nutsedge punctures were evaluated five to six weeks after application of treatments and then again another six weeks later in the tomato field study. Any early season herbicide based nutsedge suppression likely would have dissipated after this length of time. Furthermore, the increased soil surface temperature due to the plastic mulch, combined with the soil moisture at field capacity due to the drip irrigation system, may have accelerated herbicide degradation and dissipation. None of the PRE-applied treatments were effective in preventing nutsedge penetration and POST?applied halosulfuron remains the most effective treatment in controlling yellow nutsedge. Overall efficacy with respect to preventing puncturing of plastic mulch was marginal. In response to these results plastic mulch is largely limited to a single cropping season; alternatives may include thicker plastic or multiple layers. 35 LITERATURE CITED Altland, J. E., C. H. Gilliam, and G. Wehtjie. 2003. Weed control in field nurseries. HortTech. 13:9-14. Branenberger, L. P., R.E. Talbert, R. P.Wiedenfeld, J. W. Shrefler, C. L. Webber III, and M. S. Malik. 2005. Effects of halosulfuron on weed control in commercial honeydew crops. Weed Tech. 19:346-250. Earl, H. J., J. A. Ferrell, W. K. Vencill, M. W.Van Iersel, and M. A. Czarnota. 2004. Effects of three herbicides on whole plant carbon fixation and water use by yellow nutsedge (Cyperus esculentus). Weed Sci. 52:213-216. Fiegenbruge, V., S. Le Calve, and P. Mirabel. 2004. Temperature dependence of Henry?s law constants of metolachlor and diazinon. Chemosphere 57:319-327. Gaynor, J.D., A.S. Hamill, and D.C. MacTavish. 1993. Efficacy, fruit residues, and soil dissipation of the herbicide metolachlor in processing tomato. J. Amer. Soc. Hort. Sci. 118(1):68-72. Gilreath, J. P. and B. M. Santos. 2004. Herbicide dose and incorporation depth in combination with 1,3-dichloroprpene plus chloropicrin for Cyperus rotundus control in tomato and pepper. Crop Protection. 23:205-210. Grichar, W.J. 1992. Yellow nutsedge (Cyperus esculentus) control in peanuts (Arachis hypogea). Weed Tech. 6:108-112. Herbicide handbook of the weed science society of America.1983.5 th edition. P. 315-316. Herbicide handbook of the weed science society of America. 2002. 8 th edition. P. 236. 36 Kemble, J.M., M.G Patterson, and J.W Everest. 2004a. Nutsedge control in commercial vegetables. Alabama Cooperative Extension System Alabama A&M and Auburn Universities. ANR-1073. Kemble, J.M., T.W. Tyson, and L.M. Curtis. 2004b. Guide to commercial staked tomato production in Alabama. Alabama Cooperative Extension System Alabama A&M and Auburn Universities. ANR-1156. McElroy, S. J., F. H. Yelverton, I. C. Burke, and J. W. Wilcut. 2004. Absorption, translocation, and metabolism of halosulfuron and trifloxysulfuron in green kyllinga (Kyllinga brevifolia) and false-green kyllinga (K. gracillima). Weed sci 52:704-710. Obrigawitch, T., J.R. Gipson, and J.R. Abernathy. 1980 Activity of metolachlor on nutsedge. Proc. of the 33 rd annual meeting of the S. Weed Soc. P. 225. Santos, B. M., J. P. Gilreath, T. M. Motis, J.W. Noling, J.P. Jones, and J.A. Norton 2006. Comparing methyl bromide alternatives for soilborne disease, nematodes and weed management in fresh market tomato. Crop Protection. 25:690-695. Syngenta. 2005a. Syngenta Crop Protection Inc. Webpage: http://www.syngentacropprotection-us.com/prod/herbicide/Dualmagnum/. Date accessed 5/10/06. Troxler, S., J.W. Wilcut, W. D. Smith, and J.Burton. 2003. Absorption, translocation, and metabolism of foliar-applied CGA-362622 in purple and yellow nutsedge (Cyperus rotundus and C. esculentus). Weed Sci. 51:13-18. 37 Vencill, W. K., J. S. Richburge, III, J. W. Wilcut, and L. R. Hawf. 1995. Effect of MON- 12037 on purple (Cyperus rotundus) and yellow (Cyperus esculentus) nutsedge. Weed Tech. 9:148-152. Warren, L. S. JR., and H. D. Coble. 1999. Managing purple nutsedge (Cyperus rotundus) populations utilizing herbicide strategies and crop rotation sequences. Weed Tech. 13:494-503. 38 Table 1. Effects of herbicide and mulch on production of field grown tomatoes in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton, Alabama. Treatments Total Marketable Weight * (kg) Total Marketable Number * (kg) Total Unmarketable Weight * (kg) Total Unmarketable Number * (kg) Nontreated Plastic 24.01a 107.83a 14.66a 104.08a S-metolachlor PRE 24.15a 106.00a 15.64a 109.33a S-metolachlor PRE halosulfuron POST 18.55a 86.00a 15.10a 107.75a S-metolachlor & halosulfuron PRE 18.50a 85.08a 14.58a 106.67a S-metolachlor & halosulfuron PRE halosulfuron POST 19.62a 91.50a 15.83a 121.42a Nontreated Bareground 7.10b 35.37b 8.12b 60.78b Treatment < 0.0001 < 0.0001 < 0.0001 0.0002 *Means followed by the same letter are not different according to Waller Duncan? Multiple Range Test (P? 0.05). 39 Table 2. Effects of herbicide and mulch on yellow nutsedge suppression in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton, Alabama. Treatment % Control 1 Number of Punctures 1 Puncture/Sqft 1 (0.093 m 2 ) Nontreated Plastic 65.83 a 30.83 a 1.28 a S-metolachlor PRE 78.75 a 27.08 a 1.12 a S-metolachlor PRE halosulfuron POST 70.00 a 22.41 a 0.92 a S-metolachlor & halosulfuron PRE 72.50 a 25.75 a 1.07 a S-metolachlor & halosulfuron PRE halosulfuron POST 75.83 a 31.75 a 1.32 a Nontreated Bareground Treatment 0 ? ND 2 0.1569 ND 2 0.0013 ND 2 0.1867 1 Means followed by the same letter are not different according to Waller Duncan? Multiple Range Test (P? 0.05). 2 The notation of ND represents that no data was taken. 40 Table 3. Effects of herbicide and mulch on yellow nutsedge biomass in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton, Alabama. Treatment Nutsedge Biomass (kg) 1 Nontreated Plastic 0.13 ab S-metolachlor PRE 0.16 a S-metolachlor PRE halosulfuron POST 0.07 b S-metolachlor & halosulfuron PRE 0.10 ab S-metolachlor & halosulfuron PRE halosulfuron POST 0.15 ab Nontreated Bareground Treatment 0.00 c < 0.0001 1 Means followed by the same letter are not different according to Waller Duncan? Multiple Range Test (P? 0.05). Figure 1. Effects of herbicides and mulch on yield of field tomatoes pooled over two locations in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton, Alabama. Total Marketable Weight 0 5 10 15 20 25 30 metolachlor PRE metolachlor PRE Halosulfuron POST meto/halo PRE meto/halo PRE halo POST Nontreated plastic Nontreated bareground Treatment We i g ht ( k g ) marketable weight a aa a a b 1 Means followed by the same letter are not different according to Waller Duncan? Multiple Range Test (P? 0.05). 2 Tomatoes were harvested in a 9.14 m area. 41 Figure 2. Effects of herbicide and mulch on total marketable number of field grown tomatoes in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton, Alabama. Total Marketable Number 0 20 40 60 80 100 120 metolachlor PRE metolachlor PRE Halosulfuron POST meto/halo PRE meto/halo PRE halo POST Nontreated plastic Nontreated bareground Treatment # of Fr u i t marketable # a aa a a b 1 Means followed by the same letter are not different according to Waller Duncan? Multiple Range Test (P? 0.05). 2 Tomatoes were harvested in a 9.14 m area. 42 Figure 3. Effects of herbicide and mulch on total unmarketable number of field grown tomatoes in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton, Alabama. Total Unmarketable Number 0 20 40 60 80 100 120 140 metolachlor PRE metolachlor PRE Halosulfuron POST meto/halo PRE meto/halo PRE halo POST Nontreated plastic Nontreated bareground Treatment # of Fr uit unmarketable # a a a aa b 1 Means followed by the same letter are not different according to Waller Duncan? Multiple Range Test (P? 0.05). 2 Tomatoes were harvested in a 9.14 m area. 43 Figure 4. Effects of herbicide and mulch on total ummarketable weight of field grown tomatoes in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton Alabama. Total Unmarketable Weight 0 2 4 6 8 10 12 14 16 18 metolachlor PRE metolachlor PRE Halosulfuron POST meto/halo PRE meto/halo PRE halo POST Nontreated plastic Nontreated bareground Treatment We i g ht ( k g ) unmarketable Weight a a a a a b 1 Means followed by the same letter are not different according to Waller Duncan? Multiple Range Test (P? 0.05). 2 Tomatoes were harvested in a 9.14 m area. 44 Figure 5. Effects of herbicide and mulch on percent control of yellow nutsedge of field grown tomatoes in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton Alabama. Percent Control 0 10 20 30 40 50 60 70 80 90 metolachlor PRE metolachlor PRE Halosulfuron POST meto/halo PRE meto/halo PRE halo POST Nontreated plastic Nontreated bareground Treatment % C ont r ol % control a a a a a b 1 Means followed by the same letter are not different according to Waller Duncan? Multiple Range Test (P? 0.05). 2 Nutsedge Percent control was taken in a 2.5 m area. 45 Figure 6. Effects of herbicide and mulch on yellow nutsedge punctures through polyethylene mulch in field grown tomatoes in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton Alabama. Nutsedge Punctures 0 5 10 15 20 25 30 35 metolachlor PRE metolachlor PRE Halosulfuron POST meto/halo PRE meto/halo PRE halo POST Nontreated plastic Nontreated bareground Treatment # of P unc t ur e s # punctures a a a a a b 1 Means followed by the same letter are not different according to Waller Duncan? Multiple Range Test (P? 0.05). 2 Nutsedge Puncture number was gathered in a 2.5 m area. 46 Figure 7. Effects of herbicide and mulch on yellow nutsedge punctures per square foot through polyethylene mulch in field grown tomatoes in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton Alabama. Punctures per Square Foot 0 0.2 0.4 0.6 0.8 1 1.2 1.4 metolachlor PRE metolachlor PRE Halosulfuron POST meto/halo PRE meto/halo PRE halo POST Nontreated plastic Nontreated bareground Treatment # of P u nc t ur e s # puncture sqft2 a a a a a b 1 Means followed by the same letter are not different according to Waller Duncan? Multiple Range Test (P? 0.05). 2 Nutsedge puncture number was gathered in a 2.5 m area. 47 Figure 8. Effects of herbicide and mulch on yellow nutsedge biomass in field grown tomatoes in the summer of 2006 at E.V. Smith Research Center, Tallassee, Alabama and Chilton County Research and Extension Center, Clanton Alabama. Nutsedge biomass 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 metolachlor PRE metolachlor PRE Halosulfuron POST meto/halo PRE meto/halo PRE halo POST Nontreated plastic Nontreated bareground Treatment W e i ght ( k g) biomass a b ab ab ab ND 1 Means followed by the same letter are not different according to Waller Duncan? Multiple Range Test (P? 0.05). 2 Nutsedge biomass was harvested in a 2.5 m area. 48 49 CHAPTER 4 EVALUATION OF INJECTING COMBINATIONS OF SULFONYLUREAS AND S-METOLACHLOR THROUGH DRIP IRRIGATION SYSTEMS Collin W. Adcock, Wheeler G. Foshee III, Glenn R. Wehtje, and Charles H. Gilliam Abstract: Field Studies were conducted in the summer of 2006 at Auburn University?s E.V. Smith Research Station in Alabama. This study was a randomized complete block design with a total of 11 treatments of S-metolachlor (1.40 kg a.i./ha ), halosulfuron (40 g a.i./ha), trifloxysulfuron (21 g a.i./ha), S-metolachlor (1.40 kg a.i./ha ) plus halosulfuron (40 g a.i./ha), S-metolachlor (1.40 kg a.i./ha ) plus trifloxysulfuron (21 g a.i./ha) all sprayed or injected via irrigation system along with a nontreated control.. When nutsedge emergence was at peak populations approximately 60 days after application (DAA) a visual percent, numerical puncture number, and weed biomass was collected in a ten foot section of the plot area. In all F-test contrast comparisons the injected treatments provided more control of yellow nutsedge, except for the S- metolachlor/trifloxysulfuron tank mixture. The S-metolachlor/halosulfuron injected treatment had the lowest yellow nutsedge biomass (8.46 g), except for the trifloxysulfuron injected, halosulfuron injected, and S-metolachlor injected treatments. The main difference observed was the contrasts between the types of applications. Injected treatments resulted in a decrease of yellow nutsedge biomass and a higher percent control for all contrasts except the S-metolachlor/trifloxysulfuron tank mixture. Injected treatments also resulted in less nutsedge punctures. There is a need for further studies to determine the efficacy of this cost-saving application method should be repeated. Nomenclature: S-metolachlor; sulfonylurea; halosulfuron; trifloxysulfuron; Methyl bromide (MBr); yellow nutsedge (Cyperus esculentus); purple nutsedge (Cyperus rotundus) PRE, Herbigation. Additional index words: halosulfuron, trifloxysulfuron, sulfonylurea, S-Metolachlor, herbicide combinations, polyethylene Abbreviations: ALS, acetolactate synthase inhibitors; PRE, preemergence; DAA, days after application INTRODUCTION Nutsedge is a major weed problem in various horticultural and agronomic crops all over the world (Warren and Coble, 1999). Nutsedge?s wide distribution and aggressiveness is in part to its prolific vegetative reproduction by tubers and rhizomes (Vencill et al., 1995). Due to the longevity and prolific production of these tubers, Cyperus species are an extremely difficult problem in the southeastern United States (Troxler et al., 2003). Weed competition from nutsedge can reduce crop yields and quality substantially. It has been documented that nutsedge can reduce yields in some agronomic crops by 79 to 87 % (Earl et al., 2004). Cyperus esculentus (yellow nutsedge) is widespread in most areas where commercial vegetable crops are grown. The only effective means of control for nutsedge is with the use of herbicides, but there limited number of herbicides labeled for use in vegetables (Kemble et al., 2004a). 50 Halosulfuron is in the sulfonylurea class of herbicides which are all acetolactate synthase inhibitors (ALS). This class of herbicides is commonly used to control purple nutsedge (C. rotundus), yellow nutsedge (C. esculentus), and select broadleaf weed species in agronomic and horticultural crops. Halosulfuron is a systemic herbicide (Branenberger et al., 2005), and may be applied as a PRE or POST application in many situations (McElroy et al., 2004). Halosulfuron is now being used for weed control in vegetable crops (Branenberger et al., 2005), whereas it was previously used only in turfgrass systems (McElroy et al., 2004). S-metolachlor is in the chloroacetamide class of herbicides (Altland et al., 2003) labeled on tomatoes (Syngenta, 2005a). S-metolachlor is a biosynthesis inhibitor which has a multiple-site, nonspecific mode of action. S- metolachlor is mostly absorbed by emerging roots and shoots and is translocated upward throughout the weed (Syngenta, 2005a). Trifloxysulfuron is a newer ALS inhibitor with POST activity that belongs to the sulfonylurea (SU) class of herbicides. Trifloxysulfuron was originally developed for a wide range of broadleaf, sedges, and grass weed control (Branson et al., 2005). Trifloxysulfuron is commonly used as a major component for weed control in turfgrass and is now being studied for use in agronomic and horticultural crops. Due to the fact that this herbicide is relatively new, little is known about various applications, particularly in plasticulture. Trifloxysulfuron is labeled for tomato transplants, cotton, and sugarcane (Syngenta 2005a). S-metolachlor is in the chloroacetamide class of herbicides (Altland et al., 2003) labeled on tomatoes (Syngenta, 2005a). S-metolachlor is a biosynthesis inhibitor which has a multiple-site, nonspecific mode of action. S-metolachlor is mostly absorbed by 51 emerging roots and shoots and is translocated upward throughout the weed (Syngenta, 2005a). S-metolachlor has been used as a PRE and POST herbicide in agriculture since 1952 (Fiegenbruge et al., 2004). S-metolachlor has been labeled to control annual grasses, yellow nutsedge, and broadleaf weeds in many different crops such as corn, peanuts, cotton, soybeans, tomatoes, potatoes, sugar beets, forage and grain sorghum, safflower, sunflowers, and pod crops (Syngenta, 2005a). The ability of S-metolachlor to control sedges as been established in other crops (Grichar, 1992; Obrigawitch et al., 1980), however in tomato plasticulture little has been published on the use of S- metolachlor alone. Santos et al. (2006) and Gilreath and Santos (2004) have published results of combining S-metolachlor with methyl bromide (Mbr) replacements such 1,3- dichloorpropene plus chloropicrin. In 1993 (Gaynor et al.), a study was also produced in which S-metolachlor was combined with trifluralin and metribuzin and applied preplant to determine the best application rates and methods for weed control in tomatoes. The objective of this study was to evaluate injecting selected herbicide combinations (S-metolachlor and/or halosulfuron/trifloxysulfuron) as a labor saving application compared to conventional PRE-applied applications. MATERIALS AND METHODS In 2006, Field studies were conducted at Auburn Universities E.V. Smith Research Station (EVS) in Alabama. The soil type at this site was a Dothan sandy clay loam with soil pH of 6.0. This study was a randomized complete block design with a total of 11 treatments of. S-metolachlor (1.40 kg a.i./ha ), halosulfuron (40 g a.i./ha), trifloxysulfuron (21 g a.i./ha), S-metolachlor (1.40 kg a.i./ha ) and halosulfuron (40 g a.i./ha), S-metolachlor (1.40 kg a.i./ha ) and trifloxysulfuron (21 g a.i./ha) all sprayed and injected via irrigation system along with a nontreated control. Plots with heavy Nutsedge 52 infestations were chosen. The sprayed treatments were applied with a CO 2 back-pack sprayer calibrated to deliver 140 liters per hectare (L/ha). The sprayer was equipped with a three 11002 spray nozzles spaced 0.67 m apart. Injected treatments were injected using a Dosatron set to deliver a 1:64 ratio. No crop was planted since the objective was to evaluate nutsedge control along with nutsedge piercing ability of the mulch. The soil was prepared and shaped into eight parallel beds. Each plot was 7.62 m long with a 0.762 m buffer zone on both ends of the plot. After sprayed treatments were applied the drip tape along with polyethylene mulch were applied to all the rows and the irrigation was ran in order to activate the herbicides. Then one treatment at a time was connected using 0.635 cm Blue Stripe tubing spliced into the drip tape for each treatment. Approximately 60 days after application (DAA) a visual percent control, numerical puncture number, and weed biomass was collected in a three meter section of the plot area. RESULTS AND DISCUSSION ANOVA revealed some treatment differences (P ? 0.001) (Table 1and 2). The S- metolachlor/halosulfuron injected treatment had the lowest yellow nutsedge biomass (8.46 g) as this was different than all other treatments, except for the trifloxysulfuron injected, halosulfuron injected, and S-metolachlor injected treatments (Table 2). The consistent difference observed was the contrasts between the types of applications (Table 2). Injected treatments resulted in a decrease of yellow nutsedge biomass and a higher percent control. For all contrasts except the S-metolachlor/trifloxysulfuron tank mixture, when compared to PRE applications (Table 2; Figure1). Results from this one-time field study appear to be promising for the use of injecting herbicides underneath plastic mulch. Research conducted at the University of 53 Florida have been unsuccessful (Monks, per.comm) on standard 0.9 m wide beds, our study was conducted on 0.46 m wide beds with one line of drip tape. There is a need for further studies to determine the efficacy of this cost-saving application method. LITERATURE CITED Altland, J. E., C. H. Gilliam, and G. Wehtjie. 2003. Weed control in field nurseries. HortTech. 13:9-14. Branenberger, L. P., R.E. Talbert, R. P.Wiedenfeld, J. W. Shrefler, C. L. Webber III, and M. S. Malik. 2005. Effects of halosulfuron on weed control in commercial honeydew crops. Weed Tech. 19:346-250. Earl, H. J., J. A. Ferrell, W. K. Vencill, M. W.Van Iersel, and M. A. Czarnota. 2004. Effects of three herbicides on whole plant carbon fixation and water use by yellow nutsedge (Cyperus esculentus). Weed Sci. 52:213-216. Fiegenbruge, V., S. Le Calve, and P. Mirabel. 2004. Temperature dependence of Henry?s law constants of metolachlor and diazinon. Chemosphere 57:319-327. Gaynor, J.D., A.S. Hamill, and D.C. MacTavish. 1993. Efficacy, fruit residues, and soil dissipation of the herbicide metolachlor in processing tomato. J. Amer. Soc. Hort. Sci. 118(1):68-72. Gilreath, J. P. and B. M. Santos. 2004. Herbicide dose and incorporation depth in combination with 1,3-dichloroprpene plus chloropicrin for Cyperus rotundus control in tomato and pepper. Crop Protection. 23:205-210. Grichar, W.J. 1992. Yellow nutsedge (Cyperus esculentus) control in peanuts (Arachis hypogea). Weed Tech. 6:108-112. 54 Kemble, J.M., M.G Patterson, and J.W Everest. 2004a. Nutsedge control in commercial vegetables. Alabama Cooperative Extension System Alabama A&M and Auburn Universities. ANR-1073. Kemble, J.M., T.W. Tyson, and L.M. Curtis. 2004b. Guide to commercial staked tomato production in Alabama. Alabama Cooperative Extension System Alabama A&M and Auburn Universities. ANR-1156. McElroy, S. J., F. H. Yelverton, I. C. Burke, and J. W. Wilcut. 2004. Absorption, translocation, and metabolism of halosulfuron and trifloxysulfuron in green kyllinga (Kyllinga brevifolia) and false-green kyllinga (K. gracillima). Weed sci 52:704-710. Monks, D. 2007. Personnel communication. North Carolina State University. Obrigawitch, T., J.R. Gipson, and J.R. Abernathy. 1980 Activity of metolachlor on nutsedge. Proc. of the 33 rd annual meeting of the S. Weed Soc. P. 225. Santos, B. M., J. P. Gilreath, T. M. Motis, J.W. Noling, J.P. Jones, and J.A. Norton 2006. Comparing methyl bromide alternatives for soilborne disease, nematodes and weed management in fresh market tomato. Crop Protection. 25:690-695. Syngenta. 2005a. Syngenta Crop Protection Inc. Webpage: http://www.syngentacropprotection-us.com/prod/herbicide/Dualmagnum/. Date accessed 5/10/06. Troxler, S., J.W. Wilcut, W. D. Smith, and J.Burton. 2003. Absorption, translocation, and metabolism of foliar-applied CGA-362622 in purple and yellow nutsedge (Cyperus rotundus and C. esculentus). Weed Sci. 51:13-18. 55 Vencill, W. K., J. S. Richburge, III, J. W. Wilcut, and L. R. Hawf. 1995. Effect of MON- 12037 on purple (Cyperus rotundus) and yellow (Cyperus esculentus) nutsedge. Weed Tech. 9:148-152. Warren, L. S. JR., and H. D. Coble. 1999. Managing purple nutsedge (Cyperus rotundus) populations utilizing herbicide strategies and crop rotation sequences. Weed Tech. 13:494-503. 56 Table 1. Effects of herbicide applications (sprayed vs. injection) on yellow nutsedge biomass conducted at E.V. Smith Research Center, Tallassee, Alabama in the summer of 2006. Treatment Sprayed* Injected* S-metolachlor 143.15 ab 36.66 de halosulfuron 130.73 abc 46.18 de trifloxysulfuron 149.10 ab 47.81 de S-metolachlor/trifloxysulfuron 117.45 bc 83.43 cd S-metolachlor/halosulfuron 173.80 a 8.46 e Nontreated 43.98 de Significance Treatment < 0.0001 Contrasts S-metolachlor injected vs. S- metolachlor sprayed 0.0007 halosulfuron injected vs. halosulfuron sprayed 0.0062 trifloxysulfuron injected vs. trifloxysulfuron sprayed 0.0012 S-metolachlor /halosulfuron injected vs. S-metolachlor /halosulfuron sprayed < 0.0001 S-metolachlor /trifloxysulfuron injected vs. S-metolachlor /trifloxysulfuron sprayed 0.2565 *Means followed by the same letter are not different according to Waller Duncan? Multiple Range Test (P? 0.001). 57 Table 2. Effects of herbicide applications (sprayed vs. injection) on yellow nutsedge suppression conducted at E.V. Smith Research Center, Tallassee, Alabama in the summer of 2006. ccord aller Duncan? Multip e Test (P? 0.001). Treatment 58 *Means followed by the same letter are not different a ing to W le Rang Percent Control* No. of punctures* S-metolachlor injected 75.00 ab 25.83 bc S-metolachlor sprayed 40.83 cde 44.83 ab halosulfuron injected 74.16 ab 28.00 bc halosulfuron sprayed 33.33 cde 46.66 ab trifloxysulfuron injected 76.66 ab 33.16 abc trifloxysulfuron sprayed 17.50 e 51.50 a S-metolachlor /trifloxysulfuron injected 57.00 bc 37.83 ab S-metolachlor /trifloxysulfuron sprayed 32.50 cde 43.83 ab S-metolachlor /halosulfuron injected 83.33 a 14.66 c S-metolachlor /halosulfuron sprayed 27.50 de 53.00 a nontreated 45.00 cd 28.33 bc Significance Treatment < 0.0001 < 0.0001 Contrasts S- metolachlor injected vs. sprayed 0.014 0.0597 halosulfuron injected vs. sprayed 0.0037 0.0642 trifloxysulfuron injected vs. sprayed < 0.0001 0.0689 S-metolachlor /halosulfuron injected vs. sprayed 0.0001 0.0003 S-metolachlor /trifloxysulfuron injected vs. sprayed 0.0742 0.5461 59 Figure 1. Effects of herbicide applications (sprayed vs. injection) on yellow nutsedge punctures conducted at E.V. Smith Research Center, Tallassee, Alabama in the summer of 2006. Nutsedge punctures 0 10 20 30 40 50 60 me to l a c h l o r in j e c t e d m e t o la c h lo r s p r a y e d h a lo s u lf u ro n in j e ct e d h a l os u l fu ro n sp ra y e d tr i f lo x ys u l f ur o n i n j e c t e d tr i f l ox y s ul f u r o n s p r a y e d m e t o /t ri fl o x y in je c t e d me to /t ri f lo x y sp r a y e d m e t o/ h a l o i n j e c te d me t o / h al o s p r a y e d n on t r e a t e d Treatment N u m b e r of P unc t u r e s # of punctures c bc bc bc abc ab abab ab aa 1 Means followed by the same letter are not different according to Waller Duncan? Multiple Range Test (P? 0.001). 2 Nutsedge punctures were taken in a 3.14 m section of the plot. 60 Figure 2. Effects of herbicide applications (sprayed vs. injection) on percent control conducted at E.V. Smith Research Center, Tallassee, Alabama in the summer of 2006. Nutsedge Percent Control 0 10 20 30 40 50 60 70 80 90 m e to l a c h l or i njec t ed m e to l ac hl o r s p ra y e d ha l o s u l fu ro n i nj e ct e d ha l o s u lf u r o n s p ra y e d t r i f l o xy su l f u r o n in j e c t ed tr i f lo x y s ul f u r o n s pr a y e d me to /t r if l ox y i n je c t e d m e to /t r i fl o x y s p r a y e d m e to /h a l o i n j ec t e d m e to /h a l o sp r ay e d n on t re a t ed Treatment P e rcen t Co n t ro l % control a abab ab bc cd cde cdcde de e 1 Means followed by the same letter are not different according to Waller Duncan? Multiple Range Test (P? 0.001). 2 Nutsedge percent control was taken over the entire plot (7.6 m). 61 Figure 3. Effects of herbicide applications (sprayed vs. injection) on yellow nutsedge biomass conducted at E.V. Smith Research Center, Tallassee, Alabama in the summer of 2006. Nutsedge biomass (Kg) 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 m e t o la c h lo r i n j e ct e d m et ol ac h lo r sp ra y e d hal os u l f u r on i n je c t e d h al o s ul fu ro n s p ra y e d tr i f l o x y su l fu ro n i n je c te d t r if lo x y s u l f u ro n s p ra y e d m et o / t r i f l o x y in je c t e d me t o / tr i f l o xy s p ra y ed me t o/ h al o in je c t ed m et o/ h al o s p ra y e d n o nt r e a te d treatments w e i g ht ( k g) biomass de a e bc dc ab d abc de ab de 1 Means followed by the same letter are not different according to Waller Duncan? Multiple Range Test (P? 0.001). 2 Nutsedge biomass was taken in a 3.14 m section of the plot. 62 CHAPTER 5 FINAL DISCUSSION Results from a previous study conducted by Wehtje and Foshee (2004) determined that the LD 90 of PRE-applied halosulfuron on germinating nutsedge tubers along with the performance of PRE-applied S-metolachlor and followed by halosulfuron tank mixtures in these non-crop field study, led to the hypothesis that these tank mixtures should be effective in limiting nutsedge punctures during tomato production. However, results for all of my studies did not support this hypothesis. During these experiments yellow nutsedge populations of one per square foot were observed. With this level of yellow nutsedge pressure in plasticulture system, no impact on tomato yields were observed. This could be due to the abundance of nutrients and water provided through the irrigation system. Due to the fact that yellow nutsedge penetrated the plastic mulch, the integrity of the plastic was compromised and thus rendered the mulch as a single crop application. Plastic mulch alone compared to bareground without any herbicide application resulted in a three-fold increase in tomato yield as previously reported (Abdul-Baki et al.,1993; Bhella and Kwolek, 1999; Brown and Channel-Butcher, 1999; Gerber et al., 1983; Ibarra et al., 2001; Khan et al., 1999;reed et al., 1989; Sanders et al., 1999; 63 Schaleand Sheldrake, 1965). Polyethylene mulch alone suppressed nutsedge just as well as plastic mulch supplemented with selected combinations of S-metolachlor and sulfonylurea herbicides. With respect to yellow nutsedge suppression by a single herbicide the best treatment was halosulfuron PRE followed by a POST application of halosulfuron. In terms of herbicide combinations a PRE application of S- metolachlor followed by a POST application of halosulfuron was the most effective. It has been reported that the soil half life of S-metolachlor is 15 to 25 days (Herbicide Handbook, 1983). The soil half life for halosulfuron is four to 34 days depending on locations and environments (Herbicide Handbook, 2002). Lack of control with these PRE applied materials may likely be to a much faster degradation underneath the plastic mulch. This could be due in part to the higher soil temperature and soil moisture. The herbigation study showed that injecting herbicides through the irrigation system holds promise. Injecting combinations of S-metolachlor, halosulfuron, and trifloxysulfuron resulted in a decrease of yellow nutsedge biomass, a higher percent control, and less nutsedge punctures of plastic mulch compared to the PRE applied treatments. The only exception was for S-metolachlor and trifloxysulfuron injected treatment which did show some treatment differences. In conclusion, with the levels of yellow nutsedge observed in theses studies nutsedge had no effects on tomato yields, but does however prevent plastic mulch from being multi-cropped. Methyl bromide (MBr) has provided excellent control of yellow nutsedge as a soil fumigant; however it will soon be canceled for all agriculture applications (Gilreath and Santos, 2004). With these levels of yellow nutsedge (1/ft 2 ) in a 64 tomato plasticulture system there appears to be no need for yellow nutsedge control. Cheaper and safer soil fumigant like chloropicrin or metham-sodium could be used in theses situations. There is a need to investigate the soil persistence of S-metolachlor, halosulfuron, and trifloxysulfuron underneath plastic mulch. There also is a need for further studies into the potential of injecting combinations of herbicides like S- metolachlor, halosulfuron, and trifloxysulfuron via irrigation system. Since the herbicide treatments were injected on 18 inch wide beds instead of the standard 36 inch beds, future studies should look at injecting herbicides on wider beds and possible using multiple lines of drip. Also the tension strength of nutsedge needs to be investigated to determine the force yellow nutsedge must exert in order to actually puncture plastic mulch. LITERATURE CITED Abdul-Baki, A.A., J.R. Teasedale, D.J. Chitwood, and R.N. Huettel. 1993. Effect of mulches on growth and yields of muskmelon. Proc. Natl. Agr. Plastics Cong. 24:303-308. Bhella, H.S., and W.F. Kwolek. 1984. The effect of trickle irrigation and plastic mulch on Zucchini. HortScience 19(3):410-411. Brown, J.E., and C. Channell-Butcher. 1999. Effect of three row covers and black plastic mulch on the growth and yield of ?Clemson Spineless? okra. J. of Veg. Crop Prod. 5(2):67-71. Gerber, J.M., J.E. Brown, and W.E. splittstoesser. 1983. Economic evaluation of plastic mulch and row tunnels for use in muskmelon production. Proc. Natl. Agr. Plastics Cong. 17:46-50. 65 Gilreath, J. P. and B. M. Santos. 2004. Efficacy of methyl bromide alternatives on purple nutsedge control (Cyperus rotundus) in tomatoes and peppers. Weed Tech. 18:141-145. Herbicide handbook of the weed science society of America.1983.5 th edition. P. 315-316. Herbicide handbook of the weed science society of America. 2002. 8 th edition. P. 236. Ibarra, L., J. Flores, and J.C. Diaz-Perez. 2001. Growth and yield of muskmelon in response to plastic mulch row covers. Scientia Horticulturea 87:139-145. Khan, V.A., C. Stevens, C. Stevens III, M.A. Wilson, J.E. Brown, and D.J. Collins. 1999. The effect of agriplastics mulches on growth response, foliage and root endophytic and rhizoshere bacteria of ?Crimson Sweet? watermelon. Proc. Natl. Agr. Plastics Cong. 28:39-43. Reed, G.L., G.H. Clough, and D.E. Hemphill. 1989. The effect of slit, perforated, and net row covers on soil and crop temperatures and periodicity of muskmelon yield. Proc. Natl. Agr. Plastics Cong. 21:116-122. Sanders, D.C., J.D. Cure, and J.R. Schuletheis. 1999. Yield response of watermelon to planting density, planting pattern, and polyethylene mulch. HortTech. 34(7):1221- 1223. Schales, F.D., and R. Sheldrake Jr. 1965. Mulch effects on soil conditions and muskmelon response. J. Amer. Soc. Hort. Sci. 88:425-430. 66 APPENDIX EXPERIMENT PICTURES Picture 1: CO 2 backpack sprayer equipped with a one, three, or four nozzle boom, and a three liter tank used for all studies at E.V. smith Research Center, Chilton County Research and Extension Center, and Wiregrass Research and Extension Center. Picture 2: CO 2 backpack canister with regulator used for all studies at E.V. smith Research Center, Chilton County Research and Extension Center, and Wiregrass Research and Extension Center. 67 Picture 3: The four, three, and one nozzle booms, with 11002 nozzles (left), along with the spray header that fits a 3 L bottle (right) that was used in all of the studies. The four nozzle boom was used in tomato yield study at E.V. smith Research Center, Chilton County Research and Extension Center and the three nozzle boom was used in the puncture and injection study at E.V. smith Research Center, and Wiregrass Research and Extension Center. Picture 4: The New Holland TC21DA hydrostatic 21 HP tractor and a RTS90 Bush Hog Rototiller used in preparation of the puncture and injection studies at E.V. smith Research Center, and Wiregrass Research and Extension Center. Picture 5: The New Holland TC21DA hydrostatic 21 HP tractor and a 18 inch wide bedder and plastic mulch layer combo used in the puncture and injection studies at E.V. smith Research Center, and Wiregrass Research and Extension Center. 68 Picture 6: The Rhino SHV90 rototiller (left) and a Kennco Mfg 36 inch wide bed shaper (right) that was used in the preparation of the tomato yield study at E.V. Smith Research and Extension Center. Picture 7: The Kennco Mfg 36 inch wide plastic mulch layer with a drip tape layer that was used in the tomato yield study at E.V. Smith Research Center. At the Chilton County Research and Extension Center location, a Kennco MGf 36 inch wide bed shaper and plastic mulch layer combination was used. 69 Picture 8: Nontreated bareground treatment for the tomato yield study at E.V. Smith Research Center and Chilton County Research and Extension Center in the summer of 2006. Picture 9: Nontreated plastic mulched treatment for the tomato yield study at E.V. Smith Research Center and Chilton County Research and Extension Center in the summer of 2006. Picture 10: S-metolachlor (1.25 lbs a.i./A) PRE treatment for the tomato yield study at E.V. Smith Research Center and Chilton County Research and Extension Center in the summer of 2006. 70 Picture 11: S-metolachlor (1.25 lbs a.i./A) and halosulfuron (0.036 lbs a.i./A) PRE treatment for the tomato yield study at E.V. Smith Research Center and Chilton County Research and Extension Center in the summer of 2006. Picture 12: S-metolachlor (1.25 lbs a.i./A) PRE followed by halosulfuron (0.036 lbs a.i./A) POST treatment for the tomato yield study at E.V. Smith Research Center and Chilton County Research and Extension Center in the summer of 2006. Picture 13: S-metolachlor (1.25 lbs a.i./A) and halosulfuron (0.018 lbs a.i./A) PRE followed by halosulfuron POST (0.018 lbs a.i./A) treatment for the tomato yield study at E.V. Smith Research Center and Chilton County Research and Extension Center in the summer of 2006. 71 Picture 14: This picture demonstrates the lay out of the injection study at E.V. Smith Research Center. ? inch Blue Stripe? tubing was used to connect each treatment. Picture 15: Each plot was connected by splicing ? inch Blue Stripe? tubing into the drip tape during the injection study at E.V. Smith Research Center in the summer of 2006. Picture 16: The Dosatron?, which was used for injecting combinations of S-metolachlor and sulfonylurea herbicides through the irrigation system in the injection study at E.V. Smith Research Center. A Dosatron ? was also used to for injecting all fertilizers and water for the tomato yield study at E.V. Smith Research Center and Chilton County Research and Extension Center.