Bioactivity of dasanit in a mineral soil in rutabagas in the field and in storage, and effect of cooking on toxicants in the roots.

Abstract

Bioassays on the toxicity of 10G Dasanit® (O-O-diethyl O-[p-methylsulfinyl) phenyl] phosphorothioate), applied in a 4-in. band ¾ in. below the soil surface in ridged rows in the field showed that initial toxicity to 1st-stage larvae of the cabbage maggot, Hylemya brassicae (Bouché) was moderate but decreased to near zero in about 4 days. Toxicity then increased to a peak between 15 and 30 days after application and thereafter decreased at a fairly constant rate. Bioassays on rutabagas grown in soil treated with 2.5 to 30 lb toxicant Dasanit per acre banded in the row prior to seeding indicated that toxicants of Dasanit were absorbed by rutabagas and reached a peak 60 to 80 days after planting. At rates of 10 lb per acre, toxicants present in the roots at 80 days killed all test larvae (when larger roots were 3½ to 4 inches in diameter), At the 2.5 and 5 1b rates, toxicity reached a peak 70 to 80 days after planting and then decreased at a relatively constant rate. Toxicants were still detected at the normal time of harvest but decreased quickly to non-detectable levels in roots in storage. Even at the rate of 30 1b (6 to 7 times the commercially recommended application), no toxicity was detected after 2 to 3 months in storage. Cooking destroyed approximately 55% of the toxicants present in samples tested at different times after harvesting.