Different adjuvant types and glyphosate efficacy on some weeds

M. Singh, S. D. Sharma

Abstract


The effect of adjuvant types on glyphosate phytotoxicity to four annual weeds was evaluated in a greenhouse study. Glyphosate was used at a.i. rates of 0.25, 0.38 and 0.5 kg ha[sup-] and different adjuvants were formulated with glyphosate at 0.25kg ha[sup-]. The application of glyphosate with adjuvants, e.g., with ammonium sulfate (AS) or X-77 or Agri-dex to black nightshade (Solanum nigrum L.); with AS, Agri-Dex, AN, Kinetic, or X-77 to wild mustard (Sinapis arvensis L.); with Kinetic, X-77, Volt, urea, or methylated seed oil (MSO) to large crabgrass (Digitaria sanguinalis L.); and with all the adjuvants except CN and urea to barnyardgrass (Echinochloa crus-galli L.), significantly increased the percent control compared with glyphosate alone. Application of glyphosate (+AS) with X-77, L-77 or MSO to black nightshade or with either test adjuvant to wild mustard resulted in percent control more than or equal to glyphosate alone at an a.i. rate of 0.50 kg ha[sup-]. Application of glyphosate (AS) with L-77 to barnyardgrass showed some antagonistic effects, indicated by lateral shoot growth compared with the untreated plants. Glyphosate (+AS) with X-77, Kinetic or MSO applied to large crabgrass, or with Kinetic or MSO to barnyardgrass produced a further increase in percent control over glyphosate (+ AS) treatment alone. The addition of adjuvant to glyphosate reduced the necessary application rate and also improved the bioefficacy of glyphosate. The improvement in bioefficacy depends on type of adjuvant and type of plant species.

Keywords


solanum; sinapsis; digitaria; echinochloa

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283