Fruit rot control in Hunter Vineyards. Providing growers with tools to stop the rot
Abstract
Fruit rot control in Hunter Vineyards. Providing growers with tools to stop the rot
Summary
Bunch rots of grapes, are caused by a range of fungal diseases. They have a serious impact on both berry yield and grape and wine quality. There is a wealth of information on the biology and control of grey mould (Botrytis cinerea), the most commonly encountered fungal bunch rot disease.
However there are a range of other fungal pathogens associated with grape berries that are frequently referred to as non-Botrytis bunch rots. The biology of the majority of these is not well understood. This project investigated the incidence of bunch rots other than grey mould in a range of viticultural regions of NSW. The biology of two of the major non-Botrytis bunch rots of grape, ripe rot (Colletotrichum acutatum) and bitter rot (Greeneria uvicola) was investigated. The project examined the susceptibility of a number of different wine grape varieties to these two fungal pathogens. All of the varieties examined were susceptible at the post- veraison stage, with the possible exception of the Vitis hybrid, Chambourcin. Berry susceptibility is most probably linked to Brix levels.
The growth characteristics of Grey Mould, Bitter rot and Ripe rot fungi were compared. Both bitter and ripe rot tended to have optimum growth rates higher than that of Botrytis, consistent with the observation that these organisms have been recorded from vineyards in sub-tropical regions.
Furthermore ripe rot appears to tolerate exposure to Ultraviolet B (280 – 320nm) light which supports the observation that this organisms is found predominantly on fruit from open canopies (in contrast to grey mould and bitter rot).
The project has fostered on-going collaborative research between the National Wine and Grape Industry Centre and the two vineyard associations in the Hunter and Hastings Valleys. Furthermore the preliminary findings of this project have provided a framework for further research (Wine Australia project CSU03/01) on the management of non-Botrytis bunch rots in vineyards.