Pests and Diseases
The Effect of Phylloxera on Grape Vines
Phylloxera is an extremely small aphid-like insect that feeds on grape roots. Although there are 27 known species of the pest, only one of these attacks vineyards. The insect has a complex life cycle that can only be countered by grafting Vitis vinifera cuttings onto Native American rootstocks. Once a vineyard is infected, there is no effective treatment.
The History of Phylloxera in California
California wine consumption and production have both been adversely affected by the History of Phylloxera. This pest has destroyed Vitis vinifera vineyards all over the world since the mid 19th century. Under the right conditions, it can infest and threaten a vineyard within three years.
The Effect of Pierces Disease on Grape Vines
Pierces Disease is an incurable malady that is caused by a bacterium named Xylella fastidiosa. It is carried by an insect called the glassy winged sharpshooter. Pierces Disease attacks the xylem in plants which are vessels that carry nutrients and water.
Glassy Winged Sharpshooter
The glassy winged sharpshooter carries Pierces Disease, a major threat to vineyards. The primary methods of combating the spread of this insect are quarantine, pesticides and a wasp that naturally feeds on the sharpshooter. It’s one of the major vectors that spreads disease to vineyards and is a huge problem for vineyard managers in certain regions.
Powdery Mildew’s Effect on Grape Vines
Also known as odium, powdery mildew can be a tricky vineyard disease to treat. Although vines naturally produce a substance called resveratrol to combat this scourge, powdery mildew constantly develops resistance to treatments.
The Effect of Downey Mildew on Grape Vines
Downy mildew causes yellow and brown patches to form on or near the veins of leaves. It grows on the backside of the vine’s leaf and is greyish-white in color. Rain and humidity spread spores, and downey mildew attacks both shoots and grape clusters.
The Role of Black Rot on Grape Vines
When the shoots have grown to about 10 inches long, black rot becomes a threat to vineyards. Certain fungicide sprays are usually used to combat this problem, but it can develop resistance to these treatments over time.
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