Use of Quizalofop-p-tefuryl with CDA Applicator in Tillage and No-tillage Soybean

Abstract

The experiment was undertaken at the Department of Agronomy, Faculty of Agriculture, Chiang Mai University during November 1995-April 1996. The objective of the study was to compare the use of postemergence herbicide quizalofop-p-tefuryl [(+)-terahydrofurfuryl(R)-2-[4-(6-chloroquinoxalin-2-yloxy)phenoxy]propanoate] in different rates and applicators (knapsack and CDA applicator) in tillage and no-tillage soybean. In no-tillage plot, glyphosate (N-(phosphonomethyl) glycine) was applied as preplanting herbicide at the rate of 2.5 kg (ae)/ha 7 days before planting. Quizalofop-p-tefuryl at the rate of 60 and 90 g(ai)/ha was applied at 25 days after soybean planting with knapsack sprayer (flat fan nozzle; spray volume 375 l/ha) and CDA (spray volume 25 and 50 l/ ha.) The results showed that quizalofop-p-tefuryl at the rate of 60-90 g(ai)/ha applied with CDA applicator could control annual grass weeds (Digitaria adscendens; Echinochloa crus-galli: Eleusine indica, Dactyloctenium aegyptium) as effectively as that when applied with knapsack sprayer. Quizalofop-p-tefuryl showed the efficacy on annual grass weed control in both tillage and no-tillage soybean, but caused slight phytotoxicity in soybean during the first 21 days after application. The use of quizalofop-p-tefuryl for annual grass weed control produced significantly higher soybean yield over the non-treated plot. It was also found that, the crop growth and yield in no-tillage was not different from tillage soybean.