Management of staining associated with the black olive tree in Florida and the Caribbean

The oxhorn bucida tree, Bucida buceras, occurs widely in south Florida and the Caribbean. It is commonly attacked by two arthropods, an eriophyid mite, Eriophys buceras, and a caterpillar, Garella nilotica. By-products of these pests such as caterpillar frass and mite-induced galls cause severe staining of sidewalks, streets and vehicles underneath the tree canopy. The staining is so aesthetically annoying that dissatisfied homeowners may remove the trees. Studies were conducted over a 4-year period in 2 locations to evaluate systemic insecticide treatments against these pests. In Naples, during the first two years, trees receiving dinotefuran soil-root drench or acephate trunk injections showed slightly reduced staining possibly due to caterpillar suppression. During the next two years in Coral Gables, abamectin trunk injections resulted in excellent reduction in gall formation and staining. Abamectin trunk injections were most reliable in reducing property owner complaints and preserving the benefits of mature oxhorn bucida trees in the urban forest. This represents an environmentally rational approach with none of the drawbacks associated with foliar applications or soil drenching.