Patogenicidade de agroathelia coffeicola em tecidos foliares de samambaia e cafeeiro

Abstract

This study aimed to evaluate the pathogenicity of the fungus Agroathelia coffeicola isolated from bracken fern (Pteridium sp.) in leaf tissues of bracken fern (Pteridium sp.) and coffee plants (Coffea arabica) using different inoculation methods; to compare the severity between A. coffeicola isolates; to compare the severity in bracken fern and coffee plants; and to compare inoculation methods with and without wounding. The isolates were cultivated in potato-dextrose-agar medium and prepared for inoculation by two methods: without injury, using mycelial plugs of 3 mm in diameter; with injury using a wooden stick colonized by mycelium; and as controls, water-agar plugs and sterilized sticks were used, respectively. The inoculated leaf tissues were placed in acrylic boxes to create humid chambers, which were maintained using filter paper and distilled water, both sterilized. Ten days after inoculation (DAI), photographic documentation was performed to assess severity using ImageJ software. The tested isolates caused light brown necrotic spots on the leaf tissues of ferns and coffee plants and produced white aerial mycelium and light brown sclerotia. The two isolates evaluated did not show a difference in aggressiveness. The toothpick wounding method caused greater severity compared to the mycelial plug contact method. The A. coffeicola isolates used, originating from bracken fern, caused greater severity in bracken fern compared to coffee plants.