When am I likely to see it?
Foliar symptoms of the disease are most obvious in spring when the shoots are about 30cm long. This allows comparison of stunted infected shoot growth with surrounding healthy shoots. As the season progresses it gets harder to see foliar symptoms as the healthy shoots and vines obscure the infected areas (Figures 2 and 3).
The wedge shaped internal lesions are most obvious during pruning.
Can be confused with
Eutypa dieback is difficult to distinguish from Botryosphaeria dieback which is present in the grape growing regions of WA. Botryosphaeria dieback symptoms include dead or dying arms (Figures 6 and 7) and wedged-shaped internal lesions (Figure 4).
As Botryosphaeria species do not produce a toxin they do not exhibit the foliar symptoms of E. lata. Botryosphaeria species are faster growing and symptoms are likely to appear on younger vines whereas E. lata is more often associated with mature, older vines.
Sending samples to a diagnostic laboratory can differentiate the two different fungal species.
Spread
Spores of E. lata are released after rainfall (>2mm) from the fruiting bodies on the wood (charcoal areas) and can travel in the wind for kilometres. The fungus invades fresh pruning cuts or wounds and slowly moves through the vine. Pruning wounds can remain susceptible up to four weeks after the cut if no treatments are applied to them and wound healing is slow.
Vineyards where old orchards, particularly apricot orchards are located nearby, are at higher risk of infection if the disease was present there prior to establishment of the vineyard.
What to do if I suspect I have it?
Eutypa lata is a prohibited organism for Western Australia. It is important that suspect infestations are reported. Please contact the Pest and Disease Information Service (PaDIS) to report this pest on 1800 084 881 or email info@agric.wa.gov.au.