Use of Alachlor Mixing with Paraquat for Weed Control in Maize

Abstract

The experiment was conducted at Mae Hea Farm Research Station, Chiang Mai University. The study was designed to determine the efficacy of alachlor (2-chloro-2',6'-demethyl-N- (methoxymethyl)acetanilide) tank mixed with paraquat (1,1'-dimethyl-4,4’bipyridinium dichloride) for controlling weed in maize (var. Suwan 1). Herbicides were treated at 1 day after planting with the spray volume of 500 l/ha with knapsack sprayer. The land had prepared 2 weeks before herbicide application. Some weeds were germinated before herbicides application. The results showed that alachlor at the rates of more than 1.8 kg (ai)/ha gave excellent control of both annual grass weeds; Digitaria adscendens and Eleusine indica and broadleaf weeds; Amaranthus spinosus, Ageratum conyzoides, Euphorbia hirta, Phyllanthus niruri, Cloeme vicosa and Eclipta alba. A tank mixed of paraquat with alachlor provided more weed control efficacy than alachlor applied alone. The application of alachlor alone or alachlor mixing with paraquat had no phytotoxicity symptom in maize after treated. The use of alachlor alone at the rate of 1.2-2.4 kg (ai)/ha could increase yield of maize up to 11-38% compared with non-weeding plot. The combination of alachlor and paraquat gave higher yield of maize up to 18-33%.