Volume 2, Issue 8 (September 2005)
Influence of Adjuvants on Weed Control from Tribenuron
Tribenuron is a slow acting sulfonylurea herbicide that becomes more soluble as spray solution pH increases. Data from field research show differences in adjuvant enhancement of tribenuron. The most effective adjuvants with tribenuron were methylated seed oil and basic pH blend adjuvants, but the greatest activity occurred when applied together. The order of tribenuron enhancement from adjuvants was: methylated seed oil & basic pH blend>methylated seed oil=basic pH blend>crop oil concentrate=nonionic surfactant & organosilicone>nonionic surfactant=nonionic surfactant&water conditioner>nonionic surfactant&organosilicone. Methylated seed oil & basic pH blend adjuvant did not entirely overcome tribenuron antagonism of quizalofop. Tribenuron, applied as a soluble granule (SG) formulation and having properties to increase spray solution pH, provided similar weed control at a reduced rate as compared to the commercial extruded paste (XP) formulation of tribenuron. Limited research suggests that applying adjuvants on an area basis provides greater adjuvant enhancement than if applied on a percent volume basis. This would be especially important as spray volume decreases. These results generally support the concept that herbicide solubilization and absorption are necessary to maximize foliar activity.