Grapevine trunk disease is currently a very hot topic in the UK and across the world's other wine-producing regions. Trunk diseases can cause severely reduced yield, damage to fruit and vines and ultimately, vine death. The increasing incidence/observation of these diseases is likely due to increasing awareness and understanding of their symptoms and epidemiology as well as the reduced availability of effective treatments.
For the UK, I think the key findings are:
- These are complex diseases with a multitude of interactions and we need more information about the type, extent and severity across the UK.
- The most significant risk may well be to new plantings where infected vines can struggle to get established.
- Causes of infection are varied, but for Cylindrocarpon it is likely that nurseries are a source of initial infection. This is a global problem and many nurseries are working hard with the limited range of tools they have to combat these infections, however it is also possible that the UK's marginal climate makes young vines that are viable in other climates non-viable in the UK. Site selection and best practice vineyard management are therefore all the more important to maximise a new vine's chances of good establishment and a long, productive life.
- Disease management is basically limited to vineyard hygiene, pruning wound treatments and cutting back/re-planting and these are preventative not curative measures. The UKVA is currently considering a trial of pruning wound treatments that could legally be used in the UK.
The executive summary of the review is below and the Grapevine Trunk Disease Review is also available for download. I'm waiting for the papers from 7th International Workshop on Grapevine Trunk Diseases, due to be published shortly and will update this site once I have them.There is also an upcoming Wineskills Masterclass on the topic with one of the world's foremost experts on grapevine trunk disease, Dr. Laura Mugnai the the chair of the ICGTD International Council on Grapevine Trunk Diseases. I will be giving the introductory presentation.
Grapevine trunk disease is a high profile condition of the vine which appears to be increasing in incidence and severity globally. Major pathogens include Botryosphaeria spp., Cylindrocarpon spp., Eutypa lata, Phaeomoniella chlamydosporum, Phaeoacremonium aleophilum, Phomopsis viticola and others. Symptoms are variable and inconsistent but generally involve wood & leaf necrosis as well as poor growth and/or establishment, and in very acute cases, vine death. Increasingly, multiple pathogens are found in single vines, casting doubt on traditional definitions of discreet diseases, i.e. ‘Esca’ or ‘Eutypa’ and implying instead a range of interchangeable symptoms caused by a range of pathogens. Interaction between these pathogens and their environment appears to be complex and sometimes specific to species and location, with environmental stress thought to play an important role. Control measures are limited to preventing spread and the severe surgery of infected or entire vines. Vectors for infection have the potential to be varied, but pruning wounds appear to be the principle point of entry. Pruning wound treatments can reduce infection by limiting mycelial growth on open wounds but are subject to variable results and local regulations on the use and availability of fungicides. Further cultural methods as part of viticultural best practice (i.e. site selection) are also important to managing these conditions.
Download the Grapevine Trunk Disease Review (Updated, July 2012)