Evaluation of Seedbed Preparation & Alachlor Combinations for Weed Control in Soybeans

Alachlor [2'-chloro-2',6'-diethyl-N-(methoxymethyl) acetanilide] in combination with linuron [3-(3,4-dichlorphenyl)-1 methoxy-1-methylurea (n'-(3,4-dichlorophenyl)-N-methoxy-Nmehtylures)] and metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one 4-amino-6-(1,1-dimethy-ethyl)-3-(methylthio)-1,2,3-triazin-5(4 H)-one] was evaluated for its control of broadleaf and annual grasses in Mitchell soybeans (Glycine max L.) under four different tillage conditions. The experiment was conducted in the summers of 1978 and 1979. The tillage treatments evaluated were conventional tillage, double disking, single disking, and no-tillage. Alachlor at 2.2, 2.8, and 3.4 kg/ha was used alone and in combination with metribuzin at 0.4, 0.6, and 0.8 kg/ha and linuron at 0.6, 0.8, and 1.2 kg/ha. All treatments were compared with a check which received no residual herbicide application. All plots received an application of glyphosate [N,N-bis(phosphonmethyl) glycine] at 2.2 kg/ha to control emerged vegetation. The results of the experiment showed no interaction between tillage conditions and herbicide applications. There were no significant differences in broadleaf weed control or yields in the tillage plots for either 1978 or 1979. Significant differences were found in yields as affected by herbicide treatments in 1978, but none were found in 1979. Differences did not follow any logical pattern and were not consistent between years.