Phil Mulder, Oklahoma State University
Adult grape phylloxera (Daktulosphaira vitifolia) is a tiny aphid-like insect with a yellow body. The aerial form is quite common, but causes little damage. A second form of this pest can infest the roots of grapes causing serious injury, but is typically managed through the use of grafted vines onto phylloxera-resistant rootstocks. This insect is very small and may not be visible without magnification.
Leaf galling by grape phylloxera can cause distortion, necrosis, and premature defoliation of some French-American vines. The premature defoliation can, in turn, delay ripening, reduce crop quality, and predispose vines to winter injury. Generally, cultivars with smaller leaf widths are the most susceptible to aerial phylloxera, while cultivars with larger leaves are less susceptible.
|High (leaf width <5.3″)||Medium (leaf width 5.3-5.7″)||Low (leaf width 5.5-6.3″)|
|Villard Noir (83.8)||Saturn (26.9)||Campbells Early (8.6)|
|Himrod (80.2)||Verdelet (13.6)||Concord (8.5)|
|Reliance (70.5)||Fredonia (12.2)||Venus (8.0)|
|Lakemont (68.5)||Mars (3.6)|
Thus far, the aerial form of grape phylloxera has not proven to be a particularly devastating pest. Late season treatment is not recommended. Vines known to have aerial grape phylloxera infestations in previous years should be scouted on a weekly basis just prior to and after bloom. Vineyards with a history of extensive galling may require treatment with an approved insecticide when galls first appear. The root form of phylloxera can have devastating effects on vine vigor and can lead to death of the vine. Varieties or species, such as Vitis vinifera, that are known to be susceptible to the root form of phylloxera should be grafted onto a phylloxera-resistant rootstock.
Grape phylloxera overwinter in the egg stage on the cane and hatch about the time of expansion of the fifth leaf. They quickly move toward expanding leaf material where the stem mother of the subsequent crawlers begins to feed and elicits formation of the gall. About the tenth leaf stage, the crawlers are released from the gall and begin to feed and form galls on expanding leaf material. There may be as many as six to seven generations of aerial phylloxera per year in warm states.
Insect Pests of Grapes in Florida, University of Florida
Biology and Management of Grape Phylloxera, University of Arkansas
Grape Phylloxera, Ohio State University
Grape Phylloxera: Biology and Management in the Pacific Northwest, Oregon State University Extension
Field Guide for Integrated Pest Management in Pacific Northwest Vineyards, Washington State University
Reviewed by Eric Stafne, Mississippi State University and Tim Weigle, Cornell University