Fungi associated with bunch rot of grapes in the Hunter Valley

Abstract

Botrytis cinerea was isolated from apparently healthy and surface-sterilized grape Vitis vinifera L. flowers and berries. It appears that style and stigma could be the major sites of infection in Shiraz cultivar. Fungicide (benomyl) spray at bud burst and at 75% flowering lowered the incidence of B. cinerea latent infection of flowers. It is pointed out that latent infection of flowers can, under favourable conditions, lead to the development of relatively high level of inoculum and consequently high risk of berry rot. The demonstration of latent infection by B. cinerea could have important implications in the development of a management system for bunch rot control in the Hunter Valley. B. cinerea, Alternaria alternata, Rhizopus sp., Gonatobotrys simplex, Aspergillus niger, Cladosporium cladosporioides, Fusarium sporotrichioides, Epicoccum nigrum and Bipolaris bicolor were isolated frequently from flowers and berries. There appears to be diversity in the fungal flora associated with flowers and berries in Shiraz. Artificial inoculation of mature berries with A. alternata, Rhizopus sp. and A. niger resulted in some degree of rotting. It appears, therefore, that these fungi associated with berries may play a part in the development of berry rot.