Isolamento e seleção de fungos, antagonistas à pestalotia sp., Patógeno da nogueira-pecã

Abstract

The State of Rio Grande do Sul, more than half a century is a producer of pecan nut(Carya illinoensis), however, there is little research focused on the development of improvements to the culture, especially with regard to treatment of diseases. Among the diseases that attack the species, there is a leaf spot caused by Pestalotia sp., which causes spots on leaves and fruits causing its downfall, and also decreasing the photosynthetic active area of the plant. The disease is also manifested in the forest nursery seedlings, causing leaf drop, hindering its development. As a result, the objective is to test the efficacy of isolates of Trichoderma spp. as control agents of Pestalotia sp. and select fungi present in the phyllosphere pecan nuts with potential for biological control. For this, were confronted in vitro using BDA as culture medium, isolates of Trichoderma spp. with isolates of Pestalotia sp. demonstrably pathogenic. Fifteen isolates of Trichoderma spp. and two of Pestalotia sp. were obtained in the mycological collection of the Laboratory of Phytopathology DFS - UFSM. In addition, leaves of walnut-pecan were collected in orchards of some municipalities of Rio Grande do Sul. These leaves were ground in a blender with water, then were strained, and the resulting solution was inoculated in Petri plates with BDA. The grown fungi were identified and the colonies of Trichoderma spp. were isolated in test tubes with BDA for future studies. It was observed that most isolates of Trichoderma had high antagonistic power in confrontation with the two isolates Pestalotia, with a variation of resistance to the antagonist between the two fungi isolated from the pathogenic fungus.