Tufted Lovegrass (Eragrostis pectinacea) and Doveweed (Murdannia nudiflora) Control in Warm-Season Turfgrasses.

Abstract

Tufted lovegrass has been identified as a problem weed in sod production in Mississippi, Tennessee, Arkansas, Georgia and Alabama, particularly in zoysiagrass. The slow growth rate of zoysiagrass is suspected to be a contributing factor. In germination response to temperature and light studies it was determined that light was required and germination occurred over a wide temperature range. Conventional control recommendations require producers to spray reduced rates of glyphosate to control tufted lovegrass. However, producers are concerned with zoysiagrass injury, particularly to cultivars that have wider leaf blades. Preemergence-applied herbicide efficacy experiments were conducted in environmental growth chambers. Excellent control (>95%) was recorded from labeled rates of bensulide, dithiopyr, mesotrione (only 0.375 ppm concentration), metolachlor, oxidiazon, pendimethalin, and prodiamine. In small-plot, replicated experiments, mesotrione rates of 0.035, 0.072, 0.14, and 0.28 kg ai/ha were applied two or three times to a recently harvested ‘Meyer’ zoysiagrass turf infested with tufted lovegrass. Applications were made in the summer of 2006 and 2007 to approximately 14-month-old zoysiagrass. A single application of 0.28 kg ai/ha provided complete control of lovegrass but turf injury was unacceptable (>30%). Three applications of 0.072 and 0.14 kg ai/ha provided 82 and 98% control, respectively, while turf injury averaged 11 and 15%, respectively. Zoysiagrass injury was in the form of foliar bleaching and slowed growth. These results indicate mesotrione has the potential to be a useful tool in managing tufted lovegrass in zoysiagrass turf. In recent years doveweed has received increased interest due to occurrence in commercial turf and home lawns. One contributing factor is infestations found in container-grown ornamentals, further increasing its potential geographical distribution. Effective control of doveweed infestations in bermudagrass and zoysiagrass turf is lacking. Experiments were conducted in environmental growth chambers to determine optimum germination temperature. From these studies it was determined that optimum germination occurred at 32/23 C and doveweed seeds did not require light to germinate. Efficacy experiments with preemergence-applied herbicides were also conducted in the growth chambers to determine activity on scarified doveweed seeds. Labeled rates of atrazine, oxidiazon, dithiopyr, isoxaben, and metolachlor provided excellent control (>95%) while pendimethalin and prodiamine were ineffective. In field trials repeat applications (1.12 + 1.12 kg ae/ha) 21 days apart of MCPP-p-4; 2,4-D + 2,4-DP and MCPA amine provided excellent control of doveweed with minimal injury to zoysiagrass and bermudagrass turf.