Residues on Coastal Bermudagrass, Trash, and Soil Treated with Granular Endosulfan

A spittlebug, Prosapia bicincta (Say), is an important pest of Coastal bermudagrass in the Southeastern United States. In 1963 overwintering eggs deposited in ground trash and soil began hatching as usual in May. At this time newly hatched first-instar nymphs travel to small rhizomes of the bermudagrass to begin feeding and to form protective spittle masses. Logically, application of insecticides at the beginning of the hatching period should afford control. Endosulfan at 1 lb/acre was applied in a granular formulation to an infested area on May 7 and again on May 24, 1963. But observations in May and June did not show efficient control. On August 7, however, examination of the experimental area revealed few nymphs of the second generation in the endosulfan-treated plots compared with those in untreated plots. Thus, endosulfan had given unexpected control of these nymphs 75 days after the second application. An investigation of the reason seemed in order.