Granular Forms of Sodium and Potassium Azide as a Nematicide for Established Turfgrasses

Abstract

There is a need for more user-friendly chemical tools for management of plant parasitic nematodes in both cool-and warm-season turfgrasses. SEP-100 is a stabilized liquid formulation of sodium azide and was extensively researched from 2004 – 2006 as a methyl bromide preplant replacement. Research was initiated to investigate the potential of using reduced rates and granular carriers to improve tolerance in established turfs. Profile® fired ceramic clay and Biodac® cellulose complex, were chosen as the granular carriers. Sodium (NaN3) and potassium (KN3) azide were formulated to contain 10% active ingredient by weight. Research was conducted on a ‘Dominant’ creeping bentgrass [Agrostis stolonifera L. (Huds.) Farw.] putting green at Grand National GC, Opelika, AL, and on a mixture of ‘A1 and A4’ at FarmLinks GC, Sylacauga, AL. Little differences were found among formulations. Tolerance was excellent with 5.6 kg ai/ha rate applied three times at 2-wk intervals. At times, 11.2 to 16.8 rates produced unacceptable injury but bentgrass recovered in 2 to 3-wks. Injury was most pronounced when the granules were applied to wet turf and were not immediately washed into the soil with irrigation. Ring nematode (Mesocriconema spp.) control was frequently better with the higher rates, but the 5.6 rate generally provided acceptable control. The 5.6 rate of NaN3/Profile improved root length density (RLD) 1 of 2 yrs at Opelika while both KN3 formulations improved RLD at Sylacauga where ring nematode numbers were higher. Turfgrass tolerance was evaluated for ‘Mini-Verde’ hybrid bermudagrass (Cynodon dactylon x C. transvaalensis Burtt-Davy) putting green located at Auburn, AL. Each formulation was applied three times at 22.4 kg ai/ha on a 2 to 3-wk interval. In 2007, RLD was significantly improved over the non-treated with both formulations containing NaN3 while only the NaN3/Profile formulation increased RLD in 2008. Visual injury ratings showed only slight injury with all formulation and for both years. Nematode numbers were too low to evaluate efficacy. Studies were conducted at Kiva Dunes Golf Club located in Gulf Shores, AL on a ‘Tifdwarf’ bermudagrass putting green with KN3 impregnated on both carriers. First two applications were at 11.2 kg ai/ha but the final rate was increased to 22.4. Sting (Belonolaimus spp.) nematode numbers were reduced to zero in most samplings. Nemacur® and Curfew® were added as comparative treatments in 2008. Nematode infestation was again low but RLD data showed KN3/Biodac produced the highest RLD which was greater than Nemacur and equivalent to Curfew.