Controle biológico da antracnose na cultura do feijão com espécies de Trichoderma.

Abstract

The Culture of Beans (Phaseolus vulgaris) is very important for Brazilians, however, some factors might negatively affect their productivity, especially the incidence of diseases. Anthracnose (Colletotrichum lindemuthianum) is one of the main diseases, which may cause total damage to production. The objective of this work was to evaluate Trichoderma species, acibenzolar-S-methyl for resistance induction and fentin hydroxide fungicide in bean plants of the cultivars IPR Tuiuiú and IPR Quero-Quero for protection against anthracnose. Experiments were carried out in a greenhouse with evaluation of the severity of anthracnose and treatment of seeds, in detached leaf, in the field in three locations with evaluation of severity and productivity, sanitary analysis of seeds and enzymatic analysis. There was a reduction in the severity of anthracnose in both cultivars under greenhouse conditions with the application of treatments, with emphasis on Trichoderma spp. For the cultivar IPR Tuiuiú, the variables percentage of emergence and healthy seedlings were not positively affected with the application of the treatments. For the cultivar IPR Quero-Quero, in general, seed treatment with Trichoderma spp. resulted in higher percentages of emergence and healthy seedlings for both experiments. In the paper roll transmissibility test, the application of all treatments reduced the incidence of the pathogen in the seeds of both cultivars. In the detached leaf experiment, it was observed that the treatments were able to reduce the severity of anthracnose in the leaves, but no induction of systemic resistance was observed in both cultivars evaluated. In the field experiments in Ponta Grossa – PR, all the treatments tested reduced the AUDPC of anthracnose in the two cultivars, but no differences were observed in relation to the components of production in the three growing seasons. In Prudentópolis – PR there was a reduction in AUDPC with the application of treatments and an increase in productivity in relation to the control. In the city of Teixeira Soares – PR, the foliar treatment was not able to generate anthracnose reduction and there was a reduction in productivity when compared to the fungicide. The incidence of anthracnose was reduced in seeds from the fields of all treatments that received foliar application, when compared to the control. There was an increase in the concentration of phaseolin in the two cultivars tested when compared to the control. Seed treatment did not promote an increase in peroxidase activity for the cultivars, but in the presence of C. lindemuthianum there was an increase in the cultivar IPR Quero-Quero. For polyphenoloxidase, the enzymatic activity was lower than the control for the cultivar IPR Quero-Quero and in the presence of the pathogen the species T. asperellum, T. harzianum and T. koningiopsis provided an increase in polyphenoloxidase activity. The use of Trichoderma spp. may be a viable alternative for protection against C. lindemuthianum in bean seeds of cultivars IPR Tuiuiú and IPR Quero-Quero in a greenhouse. The use of Trichoderma spp. for anthracnose control might result in efficiency equal to or greater than that obtained with the use of fungicides under field conditions.