TOXICITY OF PROPOXUR IN WET AND DRY MINERAL SOIL TO ADULTS AND LARVAE OF THE CABBAGE MAGGOT, HYLEMYA BRASSICAE (DIPTERA: ANTHOMYIIDAE)

Abstract

In greenhouse tests conducted in moist acid mineral soils, propoxur was highly toxic and fast acting as an adulticide against flies of the cabbage maggot, Hylemya brassicae (Bouché), and many other types of adult insects. Some flies in contact with the surface of treated soil were killed in 30 sec or less. When banded at depths of 1, 3.5, and 7 cm, propoxur moved upward and reached peak toxicity to flies standing on the surface in ca. 5, 20, and 35 days, respectively. Deeper placement of the insecticide resulted in lower levels of peak toxicity. Toxicant from 5 to 10 cm depth treatments was still detectable 6 months after soil treatment. Adulticide tests demonstrated that propoxur could be leached downward by addition of excess water to the soil surface. Under the conditions of tests where flies in cages landed at random on treated soils in miniplots, no toxicity was detected when the surface of the treated soil became air dry.A single preplanting subsurface application of propoxur banded below the soil surface in field experiments provided all season protection against cabbage maggot infestations during normal to relatively dry growing seasons but was ineffective during abnormally wet seasons.