ABSTRACT
This work was carried out in order to evaluate the role of a simulated rain at different times after systemic fungicides application as a factor of reduction on fungicides action. Coffee plants, with 5 to 6 pairs of leaves, were sprayed with CO2 and hollow cone spray nozzles, volume of 400 L/ha and without stick addition. After 30, 60 and 120 minutes of spraying, part of plants received a rain of 20 mm for 6 minutes, applied by experimental equipment of induced rainy simulation. Coffee plants were inoculated with an aqueous suspension of Hemileia vastatrix spores (2 mg/mL), 24 hours after the fungicide spraying. Plants were maintained 72 h in acclimatized chamber, and dark conditions, at 22 ° C and relative humidity at 80 %. Evaluations were made at 37, 47 and 57 days after inoculation, based on disease incidence and in the severity of leaf area affected. Experimental delineation was randomized blocks with 14 treatments and 10 replicates and each plot represented by a plant. Control plants showed first rust disease symptoms 25 days after inoculation. Fungicide treatments showed symptoms only 37 days after inoculation. Tetraconazole and cyproconazole fungicides showed excellent coffee leaf rust control in all rainy intervals (30, 60 and 120 min) after fungicide spraying, indicating fast systemic action of the products in the leaves. There were no differences between dosis of tetraconazole tried. Light fitotoxicity was observed on the coffee leaves treated by cyproconazole fungicide.
KEY WORDS:
Persistence; chemical control; rain drag of fungicides.
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