Colletotrichum Species From Grape Ripe Rot Symptoms and Asymptomatic Grapevine Tissues

ABSTRACT Grape ripe rot (GRR), caused by species of the Colletotrichum genus, is an emerging threat to viticulture in Brazil. Significant outbreaks have been reported in the southern and northeastern grape production regions, yet little is known about the Colletotrichum species involved. To address this gap, we collected 182 isolates from symptomatic fruit and asymptomatic leaves, flowers and fruit of two Vitis species in six states of Brazil. Colletotrichum species were identified using ITS, GAPDH , TUB2 , CHS‐1 and ACT gene sequences and tested for pathogenicity on injured and uninjured berries of Vitis vinifera ‘Thompson’ and V. labrusca × V. vinifera ‘Niagara Rosada’. Most isolates (82%) were from Paraná State. Phylogenetic analyses confirmed first reports of C . melonis , C . cf. melonis , C . chrysophilum , C . hebeiense , C . gloeosporioides , C . jiangxiense and C . boninense on grapevines. Other species previously reported to cause GRR in Brazil were found, including C . nymphaeae , C. siamense , C . viniferum , C. theobromicola , C. fructicola and C . karstii . All species caused disease on injured berries. C . nymphaeae , C. siamense , C . chrysophilum and C . viniferum were isolated from both symptomatic and asymptomatic grapevine tissues, with C . nymphaeae being the most prevalent and C . viniferum mainly associated with berry lesions. Seven species were exclusively detected in asymptomatic tissues, suggesting a potential endophytic lifestyle. We hypothesise that asymptomatic grapevine leaves may serve as inoculum for all Colletotrichum species identified in this study. These findings highlight the diversity of Colletotrichum in Brazilian vineyards and the need to clarify their role in GRR.