Appropriate Weed Control for Increasing Yield and Quality of Vegetable Soybean cv. DOA Chiang Mai 84-2

Abstract

The objective of this research was to examine the appropriate weed control for increasing the yield and quality of vegetable soybean cv. DOA Chiang Mai 84-2. The experiment was conducted at Chiang Mai Field Crops Research Center in the 2 dry seasons from November 2021 to May 2023. Ten treatments were tested, using different herbicides as single agents and mixtures, at different rates of active ingredients and different application intervals. Some treatments were supplemented with hand weeding. The treatments were compared with only hand weeding treatment and no weeding treatment. The results revealed that the total dry weight of all weed controls was significantly lower and different from that of the no weed control treatment. The metribuzin was only slightly toxic to vegetable soybeans at 15 days after application (DAA). No toxicity was observed at 30 DAA. Spraying fluazifop-P-butyl and haloxyfop-R-methyl together with the broadleaf herbicide fomesafen was moderately toxic at 7 DAA, and the toxicity decreased to slightly toxic at 15-30 DAA. Weed control efficiency showed that using fluazifop-P-butyl + fomesafen together with hand weeding and using haloxyfop-R-methyl + fomesafen together with hand weeding gave moderate and good weed control. These two treatments gave the highest total yield of 1,680 and 1,595 kg/rai and gave the highest marketable yield of 1,280 and 1,244 kg/rai. All weed control treatments had a benefit-cost ratio (BCR) of more than 1 (worth investing). The application of fluazifop-P-butyl + fomesafen together with hand weeding had the highest value of an investment.