Alternaria brown spot, caused by Alternaria alternata sp. citri, attacks with more intensity the Tangelos Minneola, tangerine Dancy, and Murcotts, and with less intensity the tangelos Orlando and the tangerinas Novas, Lees and Sunburst. This disease causes severe defoliation and drop or necrotic spots in the fruits. The aim of this work was to evaluated the chemical control of brown spot, and to define the most appropriate dosage of fungicide to control it. The experimental design was split-spot, with ten treatments and 3 doses of fungicides, with five replicates, the fungicides were: azoxystrobin, pyraclostrobin, trifloxystrobin, trifloxystrobin + propinebe (2 applications) followed by 3 applications of mancozeb, difenoconazole, trifloxystrobin + propiconazole, iprodione, trifloxystrobin + tebuconazole (2 applications) followed by 3 applications of copper, copper + oil and control without fungicide. It was evaluated the incidence and number of lesions per leaf, as well the incidence of the disease on fruits and yield at the time of fruits appearing (Kg/ha). All treatments were superior to the control for yield. Among them, the treatment with trifloxystrobin + propiconazole was more profitable comparing cost and yield.
Alternaria alternata; spray program; fungicides; cost, productivity
