Abstract
The effects of diffeAZAFENIDIN EFFICACY ON WEEDS AND SEEDLING SAFETY IN CITRUSrent rates of the herbicide azafenidin alone and in the tank mix with other preemergence herbicides were examined on some important weed species of citrus groves. Azafenidin alone had immediate damaging effects on emerging seedlings of test weeds, which became bleached and died 1 week after treatment (WAT) even at the lowest rate (0.28 kg a.i./ha). No significant difference in the control of test weeds was obtained with tank mix applications of azafenidin with bromacil or diuron, or with azafenidin alone. One week after treatment, 23% control was obtained in tall morningglory, milkweed vine, and hairy beggarticks, 26% to 73% control in Brazil pusley, and 100% control in redroot pigweed when norflurazon, bromacil, diuron, or simazine herbicides were applied alone. Two weeks after treatment, all test herbicides, including azafenidin at the lowest rate of 0.28 kg a.i./ha, achieved 100% control of the test weed species. Symptoms of phytotoxicity of azafenidin were obvious on the upper leaves of citrus rootstock seedlings. The order of symptom severity was Volkamer Carrizo = Swingle, and injury increased with the rate of azafenidin. Carrizo seedling height was significantly reduced at higher rates (1.68 and 2.2 kg a.i./ha) of azafenidin 4 WAT. Upper leaves of Volkamer were bleached by 2.2 kg a.i./ha. Beyond 4 weeks, all three rootstocks resumed normal growth in all azafenidin treatments. Therefore, azafenidin could be used as an effective and potential broad-spectrum herbicide in citrus groves at lower rates (0.28 kg a.i./ha).
