Ocorrência natural de trichoderma em Laranjeiras do Sul PR e seu efeito na inibição de fitopatógenos de solo do feijoeiro

Abstract

Fungi of the genus Trichoderma are among the main agents of biological control of plant diseases. Studies on its occurrence and forms of use are essential for the efficiency of its use and management, especially in crops commonly affected by soil pathogens, such as beans. The aim of this study was to evaluate the natural occurrence of Trichoderma in different bean cultivation systems and its potential in controlling soil phytopathogens by treating seeds. For this, a survey was carried out on the diversity of fungi of the genus Trichoderma spp. in conventional cultivation systems, urban bean lots and forest sites in the municipality of Laranjeiras do Sul - PR. Then the isolates were cultivated and identified, followed by an evaluation of their potential antagonist on the soil phytopathogens Fusarium sp. Rhizoctonia solani and Sclerotinia sclerotiorum through mycelial growth using the direct pairing method, and exudates as a culture medium on phytopathogens. On seeds, the evaluation took place by the process of mycobiolization of seeds with conidia of the antagonist and exudates incubated at different times. Germination tests were evaluated through the microbiolization of bean seeds, IVG and dry matter in trays, mycelial growth by direct pairing and phytopathogen development in exudate culture medium. The results of the field survey pointed out the occurrence of Trichoderma strains in forest and crop locations, with eight strains with greater vigor and conidia production being isolated for carrying out the other tests. The results for the germination tests showed that the TH3, TH4 and TH5 isolates were beneficial in terms of seed germination, in the tests on IVG trays and dry matter there was no significant difference between the isolates, in the tests of antagonisms in direct pairing all the isolates were efficient in inhibiting mycelial growth of phytopathogens. It is concluded that in the municipality of Laranjeiras do Sul-PR, native isolates of Trichoderma spp. and its effects on soil phytopathogens were efficient, with isolates TH3, TH4 and TH5 that stood out in all tests.