Management of staining and galling associated with oxhorn bucida trees in Florida

The oxhorn bucida tree, Bucida buceras L. (Combretaceae), occurs widely in the southern Florida urban forest. It is commonly attacked by 2 arthropod species, an eriophyid mite, Eriophyes buceras Cromroy (Acari: Eriophyidae), and a caterpillar, Garella (Characoma) nilotica (Rogenhofer) (Lepidoptera: Nolidae). 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 remove the trees. Studies were conducted over a 4 yr period at 2 locations to evaluate systemic insecticide treatments against these pests. In Naples, during both 2013 and 2014, trees receiving dinotefuran soil-root drench or acephate trunk injections showed slightly reduced staining possibly due to caterpillar suppression. During 2015 and 2016 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 treatment represents an environmentally rational approach with none of the drawbacks associated with foliar applications or soil drenching.