Characterization, fungicide sensitivity and efficacy of Colletotrichum spp. from chili in Fujian, China

Chili (Capsicum frutescens L.) is an important vegetable crop worldwide because of its abundant vitamins and high capsaicin and capsochrome levels. We collected samples of chili anthracnose in different parts of Fujian Province, China, during 2017-2018. The disease incidence reached 80-90% in severely diseased fields, from which 106 isolates were isolated. The morphological characteristics of the isolates were observed and compared, and a multilocus phylogenetic analysis (ITS, ACT, GAPDH, TUB2 and CHS-1) was performed using representative isolates. Four Colletotrichum species were identified: C. fructicola, C. truncatum, C. aenigma and C. scovillei. Of these, C. aenigma was reported for the first time from chili fruit in Fujian, China. Pathogenicity was confirmed by fulfilling Koch's postulates. All of the isolates obtained were sensitive to pyraclostrobin, pyraclostrobin + salicylhydroxamic acid (SHAM) and difenoconazole based on mycelial growth inhibition (EC50 values of 0.1722-0.9783, 0.0978-0.7785 and 0.1792-2.6672 mu g/mL, respectively). In addition, pyraclostrobin, difenoconazole and pyraclostrobin + difenoconazole showed good preventive efficacy against four Colletotrichum species in greenhouse trials. In summary, this study has great importance for understanding the population structure of Colletotrichum species causing anthracnose in chili in Fujian, China, and provides useful information for the effective control of the disease in the field.