Two species of fungus Colletotrichum responsible for ripe rot of grapes

Mature winegrapes are susceptible to attack by a range of fungal pathogens, particularly when rainfall occurs close to harvest. Ripe rot is a bunch rot disease that is common in vineyards that experience warm and wet conditions as the berries mature. Until recently, ripe rot in Australia was believed to be caused solely by Colletotrichum acutatum. This article demonstrates that a second Colletotrichum species, C. Gloeosporioides, is also involved in ripe rot of grapes. The susceptibility of different grapevine varieties to the two species of Colletotrichum is demonstrated using detached berries. To further understand the infection of winegrapes, the infection of mature fruit by ripe rot fungi was investigated at the macroscopic and cellular level. The infection of winegrapes and other vine tissues are presented using a series of photographic images. Images of the infection process taken using a light microscope reveal the fungal structures responsible for berry attack at the cellular level.