Characterization and Fungicide Sensitivity of <i>Colletotrichum</i> Species Causing Strawberry Anthracnose in Eastern China

Abstract

Strawberry anthracnose caused by <i>Colletotrichum</i> spp. is one of the most serious diseases in the strawberry fields of China. In total, 196 isolates of <i>Colletotrichum</i> were obtained from leaves, stolons, and crowns of strawberry plants with anthracnose symptoms in eastern China and were characterized based on morphology, internal transcribed spacer (ITS), and β-<i>tubulin</i> (<i>TUB2</i>) gene sequences. All 196 isolates were identified as the <i>Colletotrichum gloeosporioides</i> species complex. In total, 62 strains were further identified at the species level by phylogenetic analyses of multilocus sequences of ITS, <i>glyceraldehyde-3-phosphate dehydrogenase</i> (<i>GAPDH</i>), <i>actin</i> (<i>ACT</i>), <i>Apn2-Mat1-2 intergenic spacer and partial mating type</i> (<i>ApMat</i>), <i>calmodulin</i> (<i>CAL</i>), and <i>TUB2</i>. Three species from the <i>C. gloeosporioides</i> species complex were identified: <i>Colletotrichum siamense</i>, <i>C</i>. <i>fructicola</i>, and <i>C</i>. <i>aenigma</i>. Isolates of <i>C</i>. <i>siamense</i> were tolerant to high temperatures, with a significantly larger colony diameter than the other two species when grown above 36°C. The inoculation of strawberry plants confirmed the pathogenicity of all three species. <i>C</i>. <i>siamense</i> isolates resulted in the highest disease severity. The in vitro sensitivities of <i>C</i>. <i>siamense</i> and <i>C</i>. <i>fructicola</i> isolates to azoxystrobin and three demethylation-inhibitor (DMI) fungicides (difenoconazole, tebuconazole, and prochloraz) were determined. Both species were sensitive to DMI fungicides but not to azoxystrobin. <i>C</i>. <i>siamense</i> isolates were more sensitive to prochloraz, while <i>C. fructicola</i> isolates were more sensitive to difenoconazole and tebuconazole. The present study provides valuable information for the effective management of strawberry anthracnose.