Bioassay Techniques for Dose Determination of Non-Traditional Herbicides in Cowpea (Vigna unguiculata (L) Walp.)

Abstract

Alachlor is a selective pre-emergence herbicide in legume crops. However, limited availability of these herbicides and widely availability of other (rice) herbicides (Butachlor and pretilachlor) led to need about the use of nontradition herbicides for controlling weeds. With this view the field experiment was undertaken with the objectives to study bio-efficacy of non-traditional herbicides in cowpea and to work out selectivity index (SI) value and doses for controlling mixed weed flora through bioassay technique. Results generated through the experiment indicated that the pre-emergence application on non-traditional herbicides like butachlor @ 0.77 kg ha -1 and pretilachlor @ 0.42 kg ha -1 can be applied as pre-emergence treatment in cowpea to achieve control over the weeds. However, among these two herbicides butachlor has higher degree of selectivity than pretilachlor.