EFFECT OF DIFFERENT COPPER FORMULATIONS TANK-MIXED WITH FENBUTATIN-OXIDE FOR CONTROL OF CITRUS RUST MITES (ACARI, ERIOPHYIDAE) ON FLORIDA CITRUS

One or more rates of fenbutatin-oxide (= Vendex(R)) 4 L applied alone were compared with the same rates of Vendex tank-mixed with one or mor e formulations of copper and an untreated check for control of citrus rust mite, Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae), in 4 citrus grove sites between 1988 and 1991. The copper formulations co rresponded to recommended rates in the Florida Citrus Spray Guide and included: 99% GC basic copper sulfate (pentahydrate) with 53% metallic copper, a 77% WP copper hydroxide formulation containing 50% metallic copper and a 61.4% copper hydroxide DF formulation containing 40% met allic copper. Reduced effectiveness of Vendex occurred when combined w ith all 3 copper formulations. Both copper hydroxide formulations were more disruptive in reducing the effectiveness of Vendex in controllin g citrus rust mite compared with the basic copper sulfate formulation. Increases in citrus rust mite numbers occurred in the copper-only tre atments in 2 of the 3 field experiments. In both instances, population increases in the copper-only treatments occurred at the same time as those in the untreated check trees, suggesting a stimulatory effect by the copper compounds.