Variabilidade de Colletotrichum spp. e Glomerella spp. associadas a sarna e a antracnose do feijoeiro

Abstract

The Colletotrichum genus causes diseases in several hosts, presenting wide variability among and within the species. In common bean, the anthracnose causes many damages andits etiologic agent the fungus Colletotrichum lindemuthianum. However, an emerging disease, scabies, which has been associated with the genus Colletotrichum has been observed in the production fields, but the species is not known yet. Several factors may influence the development and establishment of the pathogen in the host. This study aimed to evaluate the influence of temperature and sensitivity of different fungicides on the growth, sporulation and morphology of conidia of Colletotrichum spp. and Glomerella spp.. Regarding the sensitivity to five fungicides (methyl thiophanate, pyraclostrobin, mancozeb, chlorothalonil, pyraclostrobin + metconazole), 30 lines were evaluated for colonial diameter (DC), growth index (IVCM) and sporulation rate. The influence of three temperatures (17 ° C, 23 ° C and 33 ° C) on morphological and cytological traits was evaluated by means of DC, IVCM, sporulation, percentage of conidia germination, percentage of CATs (conidia anastomosis tubes between) and percentage of appressory formation. A wide variability were observed for all evaluated traits. There were differences between the strains of Colletotrichum spp. and Glomerella spp. sensitivity to different fungicides. The temperature influenced all the traits evaluated and for most strains of Colletotrichum spp. and Glomerella spp. the temperature of 23oC was the most adequate. Therefore, for the in vivo tests in greenhouse it is suggested to evaluate temperatures close to this value for the evaluation of the common bean scab.