Improved management strategy for Phomopsis on grapevines

Abstract

A survey and field trials were conducted to help provide vineyard and nursery managers with control strategies for phomopsis (Phomopsis viticola). The work revealed additional information about the pathogen and its pathways for infection, enabling several recommendations to be made.

Summary

Most varieties of Vitis vinifera are susceptible to infection (although symptom severity and effects on vine growth can vary between varieties) and in Australia two types of phomopsis (Type 1 and Type 2) have been recognised. This prompted research interest in the economically important Type 2 in particular, to provide a better understanding of practices, the extent of the disease, and effectiveness of various control measures.

A wide variation in the understanding of phomopsis existed among grape growers and, similarly, treatment regimes in nurseries varied according to their understanding of the means of spread and appropriate treatment.

The most important outcomes were recommendations for management of Type 2, which were: to recognise the difference between Type 1 (diaporthe) and Type 2 (a useful fact sheet is available at www.pir.sa.gov.au/factsheets: to minimise the risk of introduction by using planting material from cuttings which have been hot water treated (at 50 degrees C for 30 minutes); establish whether there is a need for a vineyard spray program (through monitoring of symptoms); consideration of  removal of a diseased vine if the vineyard has no previous history; in vineyards with a history of Type 2 apply one fungicide spray every four weeks before budburst followed by up to four in-season applications at 10 to 14 day intervals starting at 30 to 50% budburst (early sprays are the most important for effective control, particularly when wet weather occurs in early spring); refer to current fungicide recommendations, noting that some (such as fluazinam) are for use during vien dormancy and others (e.g. mancozeb) are used during the growing season, and check registrations for your state; and reduce sources of inoculums (e.g. diseased canes).