There is no substitute for experience. My inexperience in the vineyard—treated to a minor degree by reading and research—continues to humble me. The most recent example is what now appears to be an outbreak of powdery mildew that struck swiftly and dealt a terrible blow to some of my vines.
Powdery mildew is a common problem in vineyards (one source writes that if you don't think you have a powdery mildew problem in your vineyard, you aren't looking close enough). According to what I read, this is particularly true here in North Carolina and a major limiting factor in growing vinifera in my part of the state. More on powdery mildew from the folks at UC Davis can be found here.
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| The Zinfandel stripped bare under the influence of powdery mildew |
My problem started after two weeks of constant rain in September that saturated the Charlotte area but dumped record amounts of rain on South Carolina. About a week after the rain stopped, I watched as one by one the vines started shedding their leaves. I first attributed the change to the cooler weather: after all, the leaves on the poplar and sweet gum trees started their own transition to yellows and reds and began to fall.
I noticed it first on the wildly vigorous Zinfandel. Then the Cab. And the Viognier. Before I realized it, many of the vines were completely defoliated. Many, but not all. There were still plenty of vines that showed no sign of stress.
This morning, while walking Ginger, I noticed the defoliation was confined almost exclusively to the vinifera. The Zin, Viognier and Cab were nearly naked. The Merlot and Shiraz nearly so.
But many of the hybrids were unscathed. The Arandell, Baco Noir, Seyval Blanc and Chardonel were vigorous and putting on new leaves. No sign of disease at all. The Chambourcin and St. Vincent, however, showed some sign of damage, but nothing like the vinifera.
On closer examination—something experience would have dictated I do much earlier—I discovered the tell-tale signs of powdery mildew. Upon full inspection of the vineyard, I found the following, with the impact ranked from 1 (limited) to 5 (severe):
The sulfur sensitivity noted above is a three-point scale created by Double A Vineyards, the nursery where I purchased by vines. The scale is based on their own studies conducted in 2011 and 2012, where 0=no apparent injury to sulfur treatment; 1=minor visible injury; and 2=substantial visible injury. More information on powdery mildew and sulfur injury can be found on the Double A vineyards website, here.
The annotation for sulfur injury is important to note. I failed to check this prior to spraying this morning (inexperience coupled with an itchy trigger finger) when I attacked the powdery mildew outbreak with a sprayer full of Bonide Citrus, Fruit and Nut Orchard Spray.
Sulfur is the main ingredient in this product, an element which the literature tells me has been used to treat fungus for 150 years.
Unfortunately, I didn't check the sulfur sensitivity until AFTER I sprayed. I may well have done irreparable harm to the Arandell, which has been very vigorous, and the Chambourcin, which is struggling on the poorest soil in the vineyard. Time will tell how much damage I have done through the combination of inexperience and haste. I will also see if the vinifera benefit from my treatment.
But I'm a little sick about my recklessness.
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| Viognier completely defoliated by the disease |
But many of the hybrids were unscathed. The Arandell, Baco Noir, Seyval Blanc and Chardonel were vigorous and putting on new leaves. No sign of disease at all. The Chambourcin and St. Vincent, however, showed some sign of damage, but nothing like the vinifera.
On closer examination—something experience would have dictated I do much earlier—I discovered the tell-tale signs of powdery mildew. Upon full inspection of the vineyard, I found the following, with the impact ranked from 1 (limited) to 5 (severe):
- Chambourcin—3, hybrid, sulfur sensitivity 2
- St. Vincent—3, hybrid, sulfur sensitivity 0
- Seyval Blanc—1, hybrid, sulfur sensitivity 0
- Chardonel—1, hybrid, sulfur sensitivity 0
- Arandell—1, hybrid, sulfur sensitivity 2
- Baco Noir—2, hybrid, sulfur sensitivity 0
- Cabernet—5, vinifera, sulfur sensitivity 0
- Shiraz—3, vinifera, sulfur sensitivity 0
- Merlot—4, vinifera, sulfur sensitivity 0
- Viognier—5, vinifera, sulfur sensitivity 0
- Zinfandel—5, vinifera, sulfur sensitivity 0
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| The Seyval Blanc shows little sign of the disease |
The sulfur sensitivity noted above is a three-point scale created by Double A Vineyards, the nursery where I purchased by vines. The scale is based on their own studies conducted in 2011 and 2012, where 0=no apparent injury to sulfur treatment; 1=minor visible injury; and 2=substantial visible injury. More information on powdery mildew and sulfur injury can be found on the Double A vineyards website, here.
The annotation for sulfur injury is important to note. I failed to check this prior to spraying this morning (inexperience coupled with an itchy trigger finger) when I attacked the powdery mildew outbreak with a sprayer full of Bonide Citrus, Fruit and Nut Orchard Spray.
Sulfur is the main ingredient in this product, an element which the literature tells me has been used to treat fungus for 150 years.Unfortunately, I didn't check the sulfur sensitivity until AFTER I sprayed. I may well have done irreparable harm to the Arandell, which has been very vigorous, and the Chambourcin, which is struggling on the poorest soil in the vineyard. Time will tell how much damage I have done through the combination of inexperience and haste. I will also see if the vinifera benefit from my treatment.
But I'm a little sick about my recklessness.
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