Field evaluation of insecticide seed treatments for preflowering mungbean insect pests, 1981

Field evaluation of insecticide seed treatments for preflowering mungbean insect pests, 1981

1982

REP.MB-2761

Insecticides as seed treatments at 10 g a.i./100 kg seed were tested at IRRI for control of preflowering mungbean insect pests. Mungbean seeds (100 kg/ha) were shaken in a plastic bag with each insecticide and 25% gum arabic before sowing to 5 sq.m plots on Feb. 26 in a randomized complete block design with 3 replications. Plant stand was thinned to 300,000 plants/ha after emergence. The Santa Rita series soil (clayey amorphos isohyperthermic, Typic Hapludolls) -- pH = 6.5, 52% pore space, 2.7% organic matter, 34% clay, 36% silt, 30% sand -- averaged 39 and 28 C for daily maximum and minimum temperatures at 5 cm depth, respectively, the first 14 days after sowing. There was no rainfall during this dry season trial, but the plots were irrigated with overhead sprinklers. In each plot at 21 days after crop emergence (DE), 25 random plants were dissected for evidence of beanfly stem tunneling and 25 leaf bud terminals were removed randomly, placed in 70% ethyl alcohol for counting thrips under a microscope. All plots including the untreated control received postflowering insect pest protection with 0.03 kg a.i. decamethrin EC/ha 25, 35, 45 DE. Yield cuts were 5 m row per plot. Carbofuran 30ST, promecarb 38SP, chlorthiophos 25SP, and chlorthiophos 25ST provided the best control of both beanfly and thrips under heavy pest pressure. For an unexplained reason, formetanate hydrochloride 50SP gave a superior yield without significant insect control. Dioxacarb 50WP was phytotoxic to explain the low thrips count. [AS]

v.7:94, INSECTICIDE & ACARICIDE TESTS

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