8th International Workshop for Grapevine Trunk Diseases, Spain

Abstract

Dr Mark Sosnowski was funded by Wine Australia and SARDI to attend the 8^th International Workshop on Grapevine Trunk Diseases (IWGTD) in Valencia, Spain, 18-21 Jun 2012.

Summary

The objectives of the travel were to; i) acquire the latest information on grapevine trunk diseases, ii) disseminate new knowledge from SARDI grapevine research, iii) develop and strengthen collaborative linkages with key international researchers and organisations, and iv) promote a bid for Australia to host the 9^th IWGTD in 2014. The IWGTD provided an excellent opportunity to gather information on recent developments in grapevine trunk disease research. Meetings, visits and discussions with researchers from around the world, in particular Spain, have opened new doors for information exchange and collaboration as well as strengthening existing links and current collaborative research. Dr Sosnowski also met with researchers at the Polytechnic University of Valencia and the Institute for Food and Agricultural Research and Technology (IRTA) to discuss grapevine research.

Highlights of particular relevance to the Australian grape and wine industry were:

• Botryosphaeria dieback has been proposed as the name to describe the wide range of different grapevine trunk disease symptoms disease symptoms such as leaf spots, fruit rots, shoot dieback, bud necrosis, vascular discoloration of the wood and perennial cankers associated with species of the Botryosphaeriaceae.
• Botryosphaeriaceae species move endophytically beyond the lesions which could have implications in the nursery industry since the young, symptomless canes may be infected.
• Phomopsis viticola has been reconfirmed as an important grapevine trunk disease pathogen, and thus the name Phomopsis dieback is proposed to describe the disease.
• Preventative controls for Phomopsis cane and leaf spot may not completely control the disease since Phomopsis fukushii and Diaporthe eres are also responsible for wood cankers.
• Genetic studies in California suggest that grapevines are more at risk from inoculum from other grapevine and fruit crops than from riparian areas or ornamentals like willows.
• Sucker wounds on grapevines can be naturally infected by a range of trunk disease pathogens.
• Grapevine trunk disease has been attributed, in part, to grapevine nursery propagation procedures world-wide and there is a need to develop guidelines to implement practical propagation procedures.
• Contrary to previous results in other regions of the world, Spanish vineyards have been recorded with greater inoculum levels of the pathogens causing botryosphaeria dieback and esca in spring than in winter.
• NZ research showed that remove of inoculum sources such mummified berries and infested vineyard cuttings and fungicide sprays may be required before bud burst to manage botryosphaeria dieback.
• Olive trees may be an important source of inoculum for grapevine trunk disease pathogens having implications on the management of trunk diseases
• Arthropod species such as ladybirds, ants, beetles and earwigs can carry spores of trunk pathogens and they may infect pruning wounds, where they feed on bleeding sap
• Aerial imagery using Normalised Differential Vegetation Index (NDVI) was shown to be highly correlated to Esca symptoms
• Around 11% of French vineyards are unproductive due to trunk diseases
• In a long-term French study, cane-pruned vines had less foliar symptoms of eutypa dieback but more dead plants than for cordon-pruned, indicating the importance of the proximity of infection sites to the trunk.