Herbicide tank‐mixing for post‐emergence weed control in sugar beets

Summary: Tank‐mixtures of selective herbicides were evaluated for 2 years on field‐grown sugarbeets under two weed flora situations: (a) mixed floras of broad‐leaved and grass weeds and (b) weed floras of broadleaves grown beyond their stages of greatest sensitivity to herbicides. In these situations single herbicides usually fail to provide satisfactory post‐emergence weed control in sugarbeets. Of several tank‐mixtures, which could be devised for use in the first situation, ethofurnesate + Betanal AM 11, diclofop‐methyl + Betanal AM 11 and diclofop‐methyl + metamitron gave synergistic phytotoxicity to sugarbeet seedlings. Synergism in weed control, becoming apparent by an accelerated appearance of the herbicidal effects, was obtained with the mixture alloxydimeton + Betanal AM 11. This mixture was not phytotoxic and appears to be the most efficient for simultaneous control of broad‐leaved and grass weeds. From trials in the second situation it became apparent that the activity of metamitron, which was reduced on older weeds, could be restored by mixing with a non‐phytotoxic oil or a low dose of Betanal AM 11. These mixtures should be useful when growth of sugarbeets has been retarded by carried‐over herbicides, drought, frost, etc.