Preemergence herbicides trial dacthal, karmex, and treflan
Tuisamoa N and Vargo D. 1988. Preemergence herbicides trial dacthal, karmex, and treflan. Land Grant Technical Report No. 8. American Samoa Community College Land Grant Program. Pago Pago, American Samoa
Most information regarding the effectiveness of herbicides comes from studies conducted in temperate climates. Weed response to herbicides in a humid tropical climate is not completely understood. Three preemergence herbicides--Dacthal, Karmex, and Treflan--were studied to determine their levels of weed control in the humid tropical environment of American Samoa. Square meter plots were sprayed with Dacthal at 15.7 kg/ha, Karmex at 7.0 kg/ha, a combination of Dacthal and Karmex at the above rates, and Treflan at 2.3 L/ha. After 84 to 88 d, grasses and broadleaf weeds were harvested, dried, and weighed to determine their dry matter production. Plots treated with Dacthal, Karmex, Dacthal/Karmex, and Trefian produced means of 104.8, 4.1, 5.4, and 80.5 g, respectively, of grass dry matter compared to 173.1 g for a control plot, and 38.8, 2.4, 2.6, and 34.8 g of broadleaf weed dry matter compared to 27.9 g for a control plot. Dacthal and Trefian gave poor control of weeds. This may be due to the high rainfall and temperatures of the American Samoa climate. Karmex, used alone or in combination with Dacthal, gave superior control of both grasses and broadleaf weeds.