PHYLLOXERA

While the glassy-winged sharpshooter has been getting all the attention lately, phylloxera has, so far, had a far bigger impact on the world of wine than any other pest or disease. Once called phylloxera vastatrix - vastatrix meaning "the devastator" - it rivals the Irish potato famine for taking its toll on the economic well-being of those affected by it, especially those first afflicted, the French.

This devastator is a tiny, aphid-like insect, difficult for the human eye to detect at about a millimeter long. It's native to the east coast of the United States and created a lot of confusion there long ago with the first attempts to bring European wine varieties to America. They never survived and no one knew why. Now we do. In fact, many like to blame phylloxera for Thomas Jefferson's lack of success with wine grapes at Monticello, but it's believed that rot was probably the real culprit.

How The Damage Is Done:

Here's how it works: the phylloxera feeds on the roots of the vine and, in the process, injects saliva that causes the roots to swell, become deformed and begin to decay. The injuries impair the vine's ability to absorb nutrients and water and also make them more vulnerable to molds, fungus and other insects and mites. The vines seem to starve to death. At first the grower might notice a few stunted or dead vines and then the damage moves outward, often down wind. Eventually, there's no choice but to replant. Otherwise healthy vines growing in fertile soil may produce well for many years after phylloxera first attacks. Those in poor soils or that are struggling from other causes will succumb quickly.

There are several generations of phylloxera produced each summer. When the eggs hatch the young phylloxera begin crawling to other roots, causing a slow spread. They may also climb up the trunk, which can broaden the spread and speed it up. From the trunk and the leaves they can be blown to other vines. They're knocked around by tractors and other vineyard equipment, eventually reaching other vineyards. Man probably does a better job of spreading them than they do themselves, tracking them around on worker's boots and carrying them from one vineyard to the next on farm equipment and plant material. They overwinter as small nymphs on the roots, so the spread is still a danger during dormancy if the grower transfers plant material. In the spring, when soil temperatures exceed 60°F, they start feeding and growing.

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