Sunday, July 6, 2008

Troubling Signs: Vineyard Pests

There were troubling signs in the vineyard. Namely, a number of the Tempranillo vines were starting to show red leaves (which I thought may have been due to their age and some stress). More worrisome was the Zinfandel vine putting out brilliant red leaves combined with abnormal growth. So, we called in an expert, an entomologist from Valley Center.
The major concern in Southern California Vineyards is Pierce's Disease (PD) which will kill the vines. The vector is the glassy winged sharpshooter. These are interesting and crafty bugs. When they detect your hand, they move to the other side of the stem (so you can't see them). But, they're easy to trick ... put your hand on the "hidden side" and they'll come into your view.
Shortly after we planted our vines a year ago, we had an "infestation" of sharpshooters in the vineyard. We found them on many plants, and also on the "yellow sticky things". We definitely had them. When we spoke with our vineyard consultant about this, he recommended waiting until the vines had reached the cordon wire before applying "admire" -- a treatment against sharpshooters. The application was done on the last day of August last year -- what I don't know is if any of our vines are "infected" (because they were certainly exposed to the pests last year) -- and some of the red leaves I was seeing was a cause for concern.
On July 4th, we walked the vineyard with Matt, the entomologist. Good news about the Tempranillo -- the red leaves were just showing signs of age. (Picture at left.) Matt did observe some signs of stress, most likely caused by the heat wave two weeks ago -- and, as suspected, we have not been watering enough (I was trying to make the vines hunt for their water -- perhaps a little too much. In any event, no harm done -- and perhaps even stronger vines.) In the Aglianico area, we found signs of mildew, but nothing to be alarmed about -- the temperature has been well in excess of 85. Another reason we are not so concerned with mildew this year is we are not planning to harvest grapes for wine -- just a little for the farmers market.
The Zinfandel caught his attention -- but he's not 100% sure it's PD -- so, he cut samples from the vine, and will ship them to the lab for testing. We'll know in a couple of weeks if we have a problem.
We've upped the watering -- giving each vine approximately 8 gallons of water once a week.... the Petit Syrah at the bottom of the hill (which is where the rich soil is) have turned into a jungle. Within this tropical rain forest I found the King Kong of Grapes, a Godzilla cluster which was 10 clusters bunched together, on a second year vine whose trunk resembled the Ent Trees from Lord of The Rings. Since we're concerned with root growth this year -- it looks like we've got it in this area. I wonder if some of these vines have found their own source of water: the leach field?!


Nick Toscano said...

Note from University of California, Riverside, about infestation of Glassy Wing Sharp Shooters (GWSS) in the Temecula Area (just 25 miles north of Blue-Merle Country):

"Numbers of GWSS trap catches are the highest since the start of the
program in 2000. Vineyards that are not treated are in trouble. Walking
certain vineyards Gevin Kenny has found high numbers of
GWSS. Putting down AdmirePro or Alias now may be too late. It
takes at least 3-4 days for the insecticide to get into the vine. Some
experts say GWSS can transmit the bacterium that causes PD in 20
minutes of feeding. I strongly suggest that you apply Assail in your
vineyards at this time, if you have not applied AdmirePro or Alias.
We are pursuing the GWSS numbers in the citrus areas. Some citrus
areas that have been treated with AdmirePro have not shown a
decrease in GWSS. I am sure many GWSS are coming from natural
vegetation and around homeowner properties. I have had complaints
about high numbers of GWSS in residential areas of Riverside
the last 2 weeks. No spring rains and exceptionally high
weather in June has caused these high GWSS numbers."

Craig Justice said...

I've just found out that the gestation period for Pierce's Disease may be 3 years. I may not have missed that bullet yet.

Anne said...

That garden badly needs pest controls. Pest Control Melbourne