Management of Citrus Rust Mite (Acari: Eriophyidae) Resistance to Dicofol in Florida Citrus

Cage and field studies of the dynamics of the citrus rust mite, Phyllocoptruta oleivora (Ashmead), resistance to dicofol appeared to be unstable; the frequency of resistance declined quickly in the absence of selection pressure, Different regimes for dicofol (twice per year, once per year, dicofol after 2 yr of its relaxation, and untreated control) were evaluated in Florida in 2 commercial citrus groves during 1990, 1991, and 1992 seasons, We detected a positive relationship between the number of dicofol applications made per year and the frequency of resistance to dicofol. Differences in the frequencies of dicofol-resistant mites in bioassays reflected differences in the neld performance of dicofol. Use of dicofol twice per year was not appropriate because of an increased trend in the frequency of resistance from one year to the next. However, using dicofol once per year, the frequency of resistance to dicofol returned to a level equal to or less than the frequency before selection after ≈ 12 mo of dicofol application, We recommend resistance management program for dicofol for Florida citrus.