Management of Botrytis and other bunch rots

Abstract

Successful field trials testing fungicides against bunch rot organisms were carried out and showed that fungicides have a negative impact on beneficial fungi on the phylloplane of grapevines.

Summary

This project was affected seriously by the drought conditions prevailing before and during the period of the project. Lack of water caused the glasshouse trials to be abandoned.

Fungal saprophytes have a role in the environment in recycling plant material. A few fungal species are primary pathogens under specific environmental conditions. Many species may become opportunistic pathogens given a set of circumstances in which the natural and diverse environmental population has been compromised such as in the vineyard where annual applications of chemicals have been applied.

During the past decade there has been a noticeable increase in bunch damage from opportunistic organisms always present as part of the microflora on the phylloplane but now being seen as actively damaging bunches at and around harvest when the sugars are at maximum levels, berry skins are weakest and often damaged from bunch pressure and bird and insect attack.

Growers have identified environmentally sensitive management practices and protocols as their major desire for disease management. The Botrytis Best Practice Protocols were a good example of what can be achieved with grower input. Feedback this year, 2010, from the King and Alpine Valley growers who used the Botrytis Best Practice Protocols during the recent wet weather leading up to harvest found their losses were minimal compared with growers who relied on chemical management,

This project considered the role that fungicides, in particular, botryicides, had on the major bunch rot fungi found in the King and Alpine Valleys, the Yarra valley and the Mornington Peninsula. Chemicals do affect the diversity of the phylloplane organisms.