Weekend Wine Word - Phylloxera

• Posted: October 31, 2008
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• Author: James DeRosa
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• Filed under: Weekend Wine Word
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• Tags: disease, pest, phylloxera

Phylloxera, is a pest of commercial grapevines worldwide, originally native to eastern North America. These tiny, pale yellow sap-sucking insects, related to aphids, feed on the roots of grapevines. In Vitis vinifera, the resulting deformations (”nodosities” and “tuberosities”) and secondary fungal infections can girdle roots, gradually cutting off the flow of nutrients and water to the vine. Nymphs also form protective galls on the undersides of grapevine leaves and overwinter under the bark or on the vine roots; these leaf galls are not found on vines grown in California.

The majority of grape phylloxera adults are wingless females. They are generally oval shaped, but those that lay eggs are pear shaped. They are small (0.04 inch long and 0.02 inch wide) and vary in color from yellow, yellowish green, olive green, to light brown, brown, or orange. Newly deposited eggs are yellow, oval, and about twice as long as wide. Nymphs resemble adults except they are smaller.

Grape phylloxera overwinter as small nymphs on roots. In spring when soil temperatures exceed 60°F, they start feeding and growing. First instar nymphs are active crawlers and may move from plant to plant in the ground, on the soil surface, or by blowing in the wind. They may also be moved between vineyards on cuttings, boots, or equipment. Established phylloxera feed externally in groups on roots. In fall when soil temperatures fall below 60°F, all life stages die except the small nymphs. There are three to five generations each year.

Learn more about them here and here.

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