Mark Sosnowski

Molecular identification and detection of Eutypa lata in grapevine

Eutypa lata, the causal agent of Eutypa dieback of grapevines, is difficult to identify on the basis of colony morphology and is often out-competed by other fungi when isolated from wood. To facilitate diagnosis of the pathogen, we designed SCAR primers capable of amplifying DNA of E. lata and constructed a genomic DNA library from which DNA sequences specific to E. lata were identified and sequenced. SCAR primers were used to identify E. lata directly from culture without the requirement for DNA extraction or prolonged incubation periods and could also detect the pathogen in DNA isolated from grapevine wood. RFLP probes were used in slot-blot assays to detect the pathogen in DNA isolated from 1 yr old cane as well as from mature grapevine trunks. The markers developed in this study have the potential to be used as a research tool to gather information on the epidemiology of the disease and to assess the efficacy of potential control agents against E. lata.

Evaluation of Fungicides for the Management of Botryosphaeria Canker of Grapevines

The family Botryosphaeriaceae comprises a number of species that are associated with the dieback disease of grapevine (Vitis vinifera), referred to as Botryosphaeria canker. To date, there are few effective agents available for the management of this disease. In this study, fungicides were evaluated for controlling the disease using a combination of in vitro tests and field trials. Twenty fungicides registered for use on other diseases in Australian viticulture were tested in vitro for their effect on mycelial growth of four species within the Botryosphaeriaceae. The concentrations of fungicide at which 50% of mycelial growth is inhibited (EC50 values) were significantly affected both by fungicide and isolate (P < 0.001). Differences in sensitivities of the four species to the fungicides were negligible (0.41 to 0.59 mg/liter). The most effective fungicides were fludioxonil, carbendazim, fluazinam, tebuconazole, flusilazole, penconazole, procymidone, iprodione, myclobutanil, and pyraclostrobin, for which EC50 values were <1.0 mg/liter. These fungicides were evaluated under field conditions, in addition to the pruning wound protectants Bacseal Super, Garrison, and ATCS tree wound dressing, as well as the biological control agent Vinevax. In field trials, carbendazim (Bavistin), fluazinam (Shirlan), tebuconazole (Folicur), Garrison, and ATCS tree wound dressing applied to freshly cut pruning wounds were the most effective and reduced infection by Diplodia seriata and D. mutila by 41 to 65%. These results suggest that the occurrence of Botryosphaeria canker on grapevines may be reduced via treatment of pruning wounds with selected fungicides as soon as possible after pruning.

Evaluating Treatments and Spray Application for the Protection of Grapevine Pruning Wounds from Infection by Eutypa lata

Eutypa dieback threatens the sustainability of vineyards worldwide and limited treatments are available for control of the disease in grapevine. Following the loss of the effective benzimidazole fungicides, benomyl and carbendazim, there is a need to identify alternatives for the protection of pruning wounds against infection by ascospores of Eutypa lata. In this study, 24 fungicide and natural treatments were evaluated in the laboratory and field. Tebuconazole and carbendazim were the most effective fungicides for reducing colonization of pruning wounds inoculated with E. lata. Pyrimethanil and fluazinam also provided some control but were less effective than tebuconazole at the rates tested. Other treatments, such as cyprodinil + fludioxionil, pyraclostrobin, a garlic extract, and lactoferrin, reduced colonization of wounds by E. lata but require further evaluation at higher concentrations. Carbendazim applied to pruning wounds using tractor-driven sprayers reduced the incidence of pruning wound infection by E. lata to levels similar to that achieved by application with a paint brush.

Managing Grapevine Trunk Diseases With Respect to Etiology and Epidemiology: Current Strategies and Future Prospects

Fungal trunk diseases are some of the most destructive diseases of grapevine in all grape growing areas of the world. Management of GTDs has been intensively studied for decades with some great advances made in our understanding of the causal pathogens, their epidemiology, impact, and control. However, due to the breadth and complexity of the problem, no single effective control measure has been developed. Management of GTD must be holistic and integrated, with an interdisciplinary approach conducted in both nurseries and vineyards that integrates plant pathology, agronomy, viticulture, microbiology, epidemiology, biochemistry, physiology, and genetics. In this review, we identify a number of areas of future prospect for effective management of GTDs worldwide, which, if addressed, will provide a positive outlook on the longevity of vineyards in the future.