EFFECTS OF SUGARCANE BORER, WEED, AND NEMATODE CONTROL STRATEGIES IN LOUISIANA SUGARCANE

Weeds in a Louisiana sugarcane field increased the abundance of arthropod prey and predators (including the imported fire ant), and caused at least 25% less injury from sugarcane borer, Diatraea saccharalis (F.). Weed competition, however, reduced sugarcane biomass, stand density, and sugar yields. Without insecticidal control of sugarcane borer, weedy habitats were more profitable than weed-free habitats. Future study on weed conservation in the furrows alone is suggested. Spring aldicarb (nematicide-insecticide) applications reduced arthropod prey, particularly stylet-feeding herbivorous insects, for up to 10 wk. Regardless of weed cover, predator densities on the soil surface, weeds, and cane stalks were decreased by the nematicide, and percentage of internodes injured by sugarcane borers increased by at least 19%. Fenvalerate (insecticide) reduced predators and prey arthropods on the soil surface and cane stalks, including Solenopsis invicta Buren. Cicadellidae on cane foliage were reduced by the insecticide, but the yellow sugarcane aphid, Sipha flava (Forbes), was enhanced by 63%. Fenvalerate did provide at least 70% protection against the sugarcane borer, with ratoon crop sugar yields 8.7% greater than in the insecticide-free regimes. A combination of weed and sugarcane borer chemical control tactics was the most economically sound pest management strategy.