Growers should be on the lookout for signs of Syrah disorders in their vineyards as the season winds down. It’s not an easy task. Various Syrah disorders may occur singularly or concurrently and are often sporadic from one year to the next. Some may be consistent within a vineyard, or the same disorder may be sporadic throughout the vineyard.
On the Central Coast, leafroll appears to be the primary Syrah disorder, according to Mark Battany, San Luis Obispo County University of California Cooperative Extension Farm Advisor. “Leafroll virus symptoms start showing up in late July to early August, and then we start seeing red leafs appearing.”
The problem usually begins showing up in vines that are three to nine years old, according to Battany. While those vines will produce excellent wine, they are dying and will ultimately cost the grower much more than he will make.
Symptoms of Syrah disorders are often confused with irrigation or nutrition deficiencies. Off-color foliage is often the first sign. At times, some vines will have a higher pH and a higher potassium level, but it is not necessarily indicative of the problem. The cause remains a mystery. Some think it is possibly drought-related.
“We had six years of relatively dry years that coincided when a lot of Syrah came into production,” Battany says. “We’ve also seen practices such as deficit irrigation - even fairly severe deficit irrigation to try to reach a higher plateau of quality wines.”