Viticultural Information

Subject	False Spidermite
Description	In 1984 populations of Brevipalpus lewisi McGregor (Acari: Tenuipalpidae), commonly called false spidermite or flat mite, were observed for the first time damaging Vitis vinifera L. varieties in California. Apparently the increase was coincidental with a change from sulfur to triadimefon (Bayleton) for powdery mildew control. This same species is considered a pest in pomegranate orchards, where it is easily controlled with sulfur. Damaging populations also occur on American grape varieties (Vitis labrusca L.), which are resistant to mildew and do not require sulfur treatments. Damage on the foliage of vinifera varitieties (e.g., Cardinal) and American varieties (Niabell and early Niabell), flat mite causes a dehydration and blackening of the rachi and pedicels of clusters that the market finds objectionable. Because growers generally include sulfur in their powdery mildew-control program, flat mite is not considered a pest on vinifera varieties. Control on American varieties requires treatment with an acaricide.
Publications	Flaherty, D. 1992. False Spidermite. Page 265 in: Grape Pest Management, 2nd edition. University of California Division of Agriculture and Natural Resources Publication 3343, Oakland, CA.

Subject

False Spidermite

Description

In 1984 populations of Brevipalpus lewisi McGregor (Acari: Tenuipalpidae), commonly called false spidermite or flat mite, were observed for the first time damaging Vitis vinifera L. varieties in California. Apparently the increase was coincidental with a change from sulfur to triadimefon (Bayleton) for powdery mildew control. This same species is considered a pest in pomegranate orchards, where it is easily controlled with sulfur. Damaging populations also occur on American grape varieties (Vitis labrusca L.), which are resistant to mildew and do not require sulfur treatments.

Damage on the foliage of vinifera varitieties (e.g., Cardinal) and American varieties (Niabell and early Niabell), flat mite causes a dehydration and blackening of the rachi and pedicels of clusters that the market finds objectionable.

Because growers generally include sulfur in their powdery mildew-control program, flat mite is not considered a pest on vinifera varieties. Control on American varieties requires treatment with an acaricide.

Publications

Flaherty, D. 1992. False Spidermite. Page 265 in: Grape Pest Management, 2nd edition. University of California Division of Agriculture and Natural Resources Publication 3343, Oakland, CA.

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