Evaluation of Fungus-Chemical Compatibility for Melaleuca (Melaleuca quinquenervia) Control

Abstract

Integration of a fungal pathogen with herbicides may enhance melaleuca control efforts in South Florida. Hyphal inoculum of fourBotryosphaeria ribisGross & Duggar isolates were evaluated in vitro for compatibility with imazapyr, glyphosate, and a surfactant. Imazapyr at 12 to 60 mg ai/ml did not cause significant loss of inoculum viability in all four isolates within 2 h after mixing. After 24 h, inoculum viability of isolate BR-4 remained unchanged at these imazapyr concentrations, but viability of BR-1 through BR-3 was reduced. Glyphosate at the lowest concentration (32 mg ai/ml) significantly reduced inoculum viability of all isolates within 2 h. Initially, the inoculum viability of all isolates remained unaffected by 1, 5, and 10% (v/v) surfactant concentrations. After 24 h, the surfactant reduced inoculum viability of BR-2, BR-3, and BR-4 inconsistently between experiments, while the inoculum viability of BR-1 was reduced significantly at all concentrations. Mixing of the lowest concentrations of imazapyr, glyphosate, and surfactant significantly reduced inoculum viability within 2 h. This corresponded to the results obtained for glyphosate alone. These results show that hyphal inoculum ofB. ribismay be mixed with imazapyr and surfactant for field applications, but mixing the fungus with glyphosate may not be as efficacious.