Efficacy of pre and post emergence herbicides on Echinochloa spp.

Abstract

A pot culture experiment was conducted to evaluate the efficacy and determine the most suitable time of application of pre and post emergence herbicides on types of Echinochloa dominating in the rice fields of Palakkad, Kuttanadu and Kole lands during February to May 2017. Echinochloa colona, two types of Echinochloa crus-galli (type A & B) and Echinochloa stagnina were the four identified types. The pre emergence herbicide treatments included pretilachlor @ 0.75 kg a.i. ha-1, oxyfluorfen @ 0. 15 kg a.i. ha-1, pyrazosulfuron ethyl @ 1.25 kg a.i. ha-1, pendimethalin @1.5 kg a.i. ha-1, pretilachlor + bensulfuron methyl @ (0.06+ 0.6) kg a.i. ha-1and oxadiargyl @ 0.10 kg a.i. ha-1. All the herbicides were applied in both puddle sown and dry sown condition. Post emergence treatments were applied at four leaf and eight leaf stages of Echinochloa spp. and the treatments included cyhalofop butyl @ 0.08 kg a.i. ha-1, bispyribac sodium @ 0.025 kg a.i. ha-1, penoxsulam @ 0.025 kg a.i. ha-1, fenoxaprop–p–ethyl @ 0.06 kg a.i. ha-1, ethoxysulfuron @ 0.015 kg a.i. ha-1 and metamifop @ 0. 125 kg a.i. ha-1. Among the pre emergence herbicides, all except pyrazosulfuron ethyl were completely effective against all the four types of Echinochloa. Bispyribac sodium and metamifop were effective against E. colona at both four leaf and eight leaf stages, whereas penoxsulam was effective only at four leaf stage. Bispyribac sodium was highly effective against E. crus-galli (type A) at eight leaf stage. Echinochloa crus-galli (type B) was effectively controlled by metamifop when sprayed at four leaf stage, and penoxsulam at eight leaf stage. E. stagnina was tolerant to all the herbicides tried. However, cyhalofop butyl and fenoxaprop-p-ethyl although effective at the four leaf stage in reducing the survival percentage, resulted in highly persistent survivors.