Winegrowing Futures (Theme 2): Vine health and environment (protecting yield)
Abstract
This project investigated three aspects of the biology and management of fungi that limit yield. Firstly we investigated fungi involved with the rotting of grape berries, otherwise known as bunch rots. The work concentrated on those organisms associated with bunch rots in grape growing regions of NSW that are prone to summer rainfall and in particular bitter rot and ripe rot of grapes. The project has led to the development of molecular based techniques for bunch rot identification and improvements in disease management. Secondly, the identity, prevalence and distribution of Botryosphaeriaceae species in vineyards throughout winegrowing regions of New South Wales (NSW) and South Australia (SA) were also investigated. The presence, pathogenicity and genetic diversity of Botryosphaeriaceae from tissues other than wood were established. Botryosphaeriaceae were isolated from dormant buds, flowers, pea-sized berries and mature berries. Morphological and molecular identification revealed nine Botryosphaeriaceae species on grapevines in eastern Australia as well as Eutypa lata and other Diatrypaceae species. Eutypa dieback was more widespread in NSW than first thought. In vitro and field trials resulted in several fungicides that may be applied to pruning wounds to reduce Bot canker in vineyards. Thirdly, the causes and control of young vine decline (YVD): a serious disease complex where newly planted grafted grapevines die soon after planting or have retarded growth and low yields until eventually dying in following seasons. YVD in the Riverina is caused by co-infection by two different wound/root-invading fungi. First Botryosphaeria is present in cuttings from infected rootstock mother-vines. These cuttings then become further invaded by Cylindrocarpon and probably again by Botryosphaeria in the nursery. Cylindrocarpon disrupts root function and Botryosphaeria invades the xylem. Although management practices, such as composts and the addition of biochar, can reduce stress and alleviate symptoms, the only viable solution is to prevent the sale of diseased young vines through improved nursery practices.