|Suspected Leafroll Virus in Cabernet Sauvignon.|
Looking vineyards this week some vines are showing red leaf symptoms - generally Cabernet Sauvignon and Shiraz.
We suspect this is Leaf Roll Virus expressing itself in early Summer. These Shiraz vines pictured are showing reddening and some early signs of the leaf curling.
Vine symptoms are not a reliable indicator of the presence of leafroll virus because other factors may lead to similar symptoms. Laboratory analytical techniques can be used to positively identify the virus in grapevines. Waite Diagnostics use the PCR method to test for leafroll and other grapevine viruses.