Compatibilidade in vitro de Trichoderma spp. frente a diferentes agrotóxicos

Abstract

Agriculture has been changing over time, and this requires adapting farmers. One of these changes is related to how the phytosanitary problems, insects and weeds will be solved. One of the currents of thought that originated in the agricultural revolution delimits the use of agrochemicals to solve these problems, while another is based on a more sustainable agriculture, with the use of natural products. Although they are two distinct streams, the simultaneous use of the two treatments is a common practice among farmers. Based on this, studies are needed to clarify the question of compatibility between the two methods, since this possibility would denote an increase in the productive system. Thus, the present work has contributed to the studies in this area in which different pesticides were used and their interference in the growth and in vitro sporulation variables of three Trichodema isolates was evaluated, two of them being from commercial products (Trichoderma asperellum isolated from the commercial product Quality®, and Trichoderma harzianum, obtained from the commercial product StimuControl®), and Trichoderma harzianum, isolated from the soil of northwestern Rio Grande do Sul. The products used were four for seed treatment, two treatments fungicides (fludioxonil + metalaxyl-M and carboxin + thiram), an insecticide (thiamethoxan) and one with fungicidal principles and insecticides (pyraclostrobin + methyl thiophanate + fipronil), plus two emergency emergence herbicides (glyphosate and paraquat). Seed treatments obtained negative results on the variables tested, mainly fungicides (fludioxonil + metalaxyl-M, carboxin + thiram and pyraclostrobin + methyl thiophanate + fipronil), which reduced growth and sporulation by up to 80%. in a classification of products toxic to isolates. The thiamethoxan ingredient presented similar results to the fungicides for the mycelial growth variable, but for the sporulation variable, obtained the means closest to the control, even presenting an increase of 5% for the T. harzianum soil isolate. The two herbicides (glyphosate and paraquat) were classified as compatible with the T. harzianum soil isolate and were moderately toxic to T. asperellum and T. harzianum strains isolated from commercial products. The two herbicides presented a reduction in growth ranging from 15% to 30%, reducing sporulation of strains from 10% to 40%.