Developing pruning wound protection strategies for managing Eutypa dieback

Abstract

Background and Aims: Eutypa dieback is an economically important disease of grapevines and a major threat to vineyard longevity throughout the world. Developing effective preventative strategies offers the best means of control. In this study, pruning wound protectants and various spray applications were evaluated for their ability to prevent infection by ascospores of Eutypa lata. Methods and Results: Fungicides and natural alternative treatments were applied by hand to grapevine pruning wounds in winter prior to inoculation with E. lata. In a series of greenhouse and field experiments, tebuconazole, pyraclostrobin, fluazinam, garlic extract and lactoferrin significantly reduced infection. A range of tractor-driven sprayers was used to apply tebuconazole to pruning wounds, and those which provided good coverage reduced infection by E. lata to a level similar to that when tebuconazole was applied with a paintbrush. Conclusion: Eutypa dieback can be controlled with several fungicides and natural treatments. Tractor-driven sprayers, which by design or modification can efficiently deliver maximum possible coverage at high output rates, can be used for application of pruning wound treatments. Significance of the Study: Results of this study contributed to registration of fungicides for use as pruning wound treatments to control E. lata in Australia. Demonstrating the ability of tractor-driven sprayers to apply treatments effectively has led to greater industry adoption of dormant treatments and may decrease the future impact of Eutypa dieback.

Incidence and severity of Eutypa dieback in grapevines are related to total surface area of pruning wounds

“…Dead infected wood of grapevines, and of other hosts of E. lata which may be readily found in abandoned orchards and riparian strips, is a source of airborne ascospores which increases the potential for infection of new pruning wounds (Carter 1991, Munkvold et al 1993). Painting or spraying grapevines with a preventative treatment immediately following pruning (Ayres et al 2017) has been shown in field trials to reduce the proportion of pruning wounds infected by E. lata . Until preventative practices are universally adopted, commencing with vineyard establishment, conclusions with regard to the effect of operations, such as pruning, on the incidence and severity of disease will be better drawn from vineyards with the same management, such as the Kalimna vineyards used here, rather than vineyards of the same age.…”

“…Where cultivars are particularly susceptible to E. lata , yield decline can be expected to commence within 15 years of vineyard establishment (Munkvold et al 1994). Acceptable disease management can be achieved by application of preventative paints or sprays (Sosnowski et al 2008, Ayres et al 2017). Although there is no cure, remedial surgery can control disease if all infected material is removed (Sosnowski et al 2011).…”

Protection of grapevine pruning wounds against Phaeomoniella chlamydospora and Diplodia seriata by commercial biological and chemical methods

“…In our study, we followed the official method of European countries to evaluate pruning wounds protection products against E. lata, which suggests carrying out fungal inoculations hours after the application of preventive treatments (EPPO, 2017). Accordingly, in most of the previous pruning wound protection trials, the time elapsed between pruning wound protection and GTD fungal inoculation was 24 hours (John et al, 2005;Sosnowski et al, 2008Sosnowski et al, , 2013Halleen et al, 2010;Rolshausen et al, 2010;Kotze et al, 2011;Amponsah et al, 2012;Pitt et al, 2012;Díaz and Latorre, 2013;Ayres et al, 2017;Sosnowski and Mundi, 2019). This short time between BCA treatments application and artificial fungal inoculations could also have explained the poor performance exhibited by Trichoderma-based commercial formulations in our study.…”

“…Similar results were observed in other studies where several fungicides and BCA treatments were compared as pruning wound protectants in the same field trial. In Australian vineyards, liquid and paste fungicide formulations were more effective than Trichoderma-and Bacillus subtilis-based formulations against D. seriata and Diplodia mutila (Pitt et al, 2012), and Eutypa lata (Ayres et al, 2017) infections, respectively. Halleen et al (2010) also reported that fungicides were more effective than Trichoderma spp.…”

“…Wound applications of pyraclostrobin alone were effective for the control of D. seriata and P. chlamydospora in Chile (Díaz and Latorre, 2013) and California (Rolshausen et al, 2010) vineyards. Moreover, this active ingredient significantly reduced infections caused by fungi associated with Botryosphaeria dieback (Rolshausen et al, 2010), Eutypa dieback (Sosnowski et al, 2008(Sosnowski et al, , 2013Rolshausen et al, 2010;Ayres et al, 2017), and esca (Rolshausen et al, 2010), under field conditions.…”