LONG-TERM CONSERVATION TILLAGE STUDIES - IMPACT OF NO-TILL ON SEEDCORN MAGGOT (DIPTERA, ANTHOMYIIDAE)

A long-term study (12 years) was conducted to determine the feasibilit y of growing soybean in rotation with corn on the hill land of southea stern Ohio, USA, using conservation tillage practices that included in vestigating the effect of tillage on populations of seedcorn maggot, D elia platura Meigen. Corn and soybean were grown using various managem ent and conservation tillage practices including no-till, paraplow, an d chisel plow, multiple diskings, and conventional tillage. Adult seed corn maggots were sampled over a 12-year period to assess the impact o f tillage practice on population density. No-till and paraplow, where there was little soil disturbance, generally had fewest adults. Chisel plowing caused a slight increase in numbers of adults, although densi ties were never as high as plowing and/or disking treatments. The larg est number of adults were collected from areas where soil was disturbe d, either by plowing and disking or by multiple diskings. This study p resents evidence that no-till systems do not enhance seedcorn maggot p opulations and indicates that population increases are associated with tillage systems involving substantial soil disturbance. (C) 1997 Else vier Science Ltd.