Interactions of Diclofop-Methyl and 2,4-D in Cultivated Oats (Avena sativa)

The chlorophyll levels and growth of oat (Avena sativa L. 'Elgin') seedlings were drastically reduced after foliar application of diclofop -methyl {methyl 2[4-(2,4-dichlorophenoxy)phenoxy] propanoate1 . The leaves were chlorotic and necrotic with the newly emerging eaves being most affected. Plants treated with 2,4-D [(2,4-dichlorophenoxy)acetic acid] were similar to the controls. When 2,4-D was applied to intact plants in combination with diclofopmethyl the toxicity symptoms produced by diclofop-methyl were reduced. Diclofop-methyl disrupted membrane integrity and inhibited chlorophyll formation in excised leaf segments. Addition of 2,4-D with diclofop-methyl did not change the effects produced by diclofopmethyl alone in excised leaf segments. Additional index words. Antagonism, chlorophyll, membrane.