Primary Linear Alcohol Ethoxylates as Adjuvants for Primisulfuron

Greenhouse experiments were conducted to evaluate the effect of carbon chain length and percent ethoxylation of primary linear ethoxylated alcohols on postemergence control of johnsongrass and quackgrass with primisulfuron. Control of johnsongrass and quackgrass was greatest with primisulfuron plus the experimental ethoxylated alcohols 1412-60 and 1412-70 which had chain lengths of 14 and 12 carbon atoms (60:40 ratio) and 60 or 70% ethoxylation. Control of these two weed species decreased when primisulfuron was applied with ethoxylated linear alcohols of similar chain lengths but decreased percent ethoxylation or with alcohols of similar percent ethoxylation but decreased carbon chain length. Quackgrass and johnsongrass control with primisulfuron plus 1412-60 or 1412-70 was equal to or greater than the control obtained with primisulfuron plus the commercial adjuvants of the nonionic, organosilicone, sunflower methyl ester, or crop oil concentrate types. The experimental adjuvant 1412-70 provided equal or greater uptake and translocation of 14C-primisulfuron in johnsongrass and quackgrass compared to four commercial adjuvants.