Abstract
Management strategies for eutypa dieback have been optimised by identifying new pruning wound treatments that control eutypa dieback, generating efficacy data for fungicide label registration and demonstrating the use of commercial sprayers to apply treatments to pruning wounds effectively.
Summary
Eutypa dieback is a major disease of grapevines worldwide which causes considerable economic loss to the $8.3 billion Australian wine industry and is caused by the fungus Eutypa lata. The fungus infects vines through pruning wounds and colonises wood tissue causing dieback of cordons, stunting of green shoots, leaf distortion, poor fruit set, uneven berry ripening and, if not controlled, eventually kills vines. Eutypa dieback is now recognised as a significant problem in most cool climate growing regions of southern Australia where it threatens the sustainability of many vineyards.
Currently, the only method of controlling eutypa dieback, once established in vines, is by removal of all infected wood tissue from the vine using remedial surgery. A more cost effective method of control of the disease is to prevent entry of E. lata into the vines by protecting pruning wounds.
A number of pruning wound treatments, including fungicides and alternative products, have been evaluated for efficacy in controlling eutypa dieback. Fungicides from three fungicide activity groups, Folicur (tebuconazole), Shirlan (fluazinam) and Cabrio (pyraclostrobin), provided control of the disease at the label rates currently recommended for control of other grapevine diseases. Permits are being sought for their use as pruning wound protectants during vine dormancy. Use of these products would provide a greater range of options for growers to manage the disease.
The “alternative” products, garlic, lactoferrin and the biocontrol product Serenade, provided some control of eutypa dieback, but less than that of conventional fungicides. These may provide options for organic growers and those wishing to reduce use of synthetic fungicides.
A detached cane assay (DCA) was developed that allows assessment of pruning wound protectants using live single-node cuttings under controlled conditions. This assay can provide efficacy data on wound treatments in as little as 6 weeks from establishment, compared with up to 18 months for a field trial. The method also allows for evaluation of treatments at decreased disease pressure, more reflective of that occurring naturally. In order to assess the ability of treatments to control eutypa dieback, field trials must be conducted, but the DCA allows for a rapid screening of treatments to support field results and to generate additional data to assist with product registration.