SPLIT APPLICATIONS AND TANK MIX COMBINATIONS OF DICLOFOP-METHYL AND MCPA FOR WEED CONTROL IN BARLEY

Abstract

Injury to barley (Hordeum vulgare L.) caused by the foliar-applied wild oat (Avena fatua L.) herbicide diclofop-methyl {methyl 2-[4-(2,4-dichlorophenoxy) phenoxy] propanoate} was evaluated and application methods were modified to reduce or eliminate the injury and loss in yield. Diclofop-methyl caused shoot chlorosis and inhibited growth of both barley and wild oats. In barley, assimilate transport to the roots was reduced and this effect was not altered by MCPA {butyl ester of [(4-chloro-o-tolyl)oxy] acetic acid}. Injury to barley from split applications of diclofop-methyl was minimal, and wild oat control was maintained as long as the interval between applications was less than 7 days. A 4-day interval between MCPA and diclofop-methyl prevented most of the antagonism that occurs with application of a tank mixture of the two herbicides. If diclofop-methyl at one-third of the total dosage was applied in one treatment, followed 4 days later by the remainder of the dosage mixed with MCPA, barley injury was minimal and control of both wild oats and Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) was excellent.