CHEMICAL CONTROL OF LIOCORIS SPP., ADELPHOCORIS SPP. AND PLAGIOGNATHUS MEDICAGUS ARRAND (HEMIPTERA: MIRIDAE) IN NORTHERN ALFALFA SEED FIELDS

Abstract

One application of 1.25 pounds DDT, 0.50 pound dieldrin, or 1.0 pound heptachlor per acre when the alfalfa had just started to bud practically eliminated Adelphocoris spp. and Plagiognathus medicagus before they caused noticeable damage, and kept Liocoris spp. infestations below 0.3 per sweep throughout the season in replicated plot tests in 1956 and 1957. The residual toxicity provided by these treatments should ensure adequate control of plant bugs in alfalfa grown for seed in the northern agricultural areas of Western Canada.One application of 0.75 pound DDT or 0.5 pound heptachlor effectively controlled Adelphocoris spp. and P. medicagus, but permitted Liocoris spp. infestations to reach about 2.0 bugs per sweep after 6 or 7 weeks. The residual toxicity provided by these treatments would not be adequate to prevent damaging infestations of Liocoris spp. from developing in some years.