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Adults are about 3 mm long, and pale
yellow-white in color. |
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| WALH nymphs are white to yellow, with early
instars having red eyes. |
|
The primary host of WALH is apple, but it also is found on peach, plum, and cherry. WALH prefer mature leaves and do not tend to feed at the leaf edge. WALH cause a whitish stippling effect (see photo, at left) on leaves and they drop a hard to remove excrement on fruit, mostly in the second generation. There are two generations of WALH. They are present from spring through harvest.
Monitoring and thresholds: Estimate number per leaf. More first-generation will be on spur leaves; most summer-generation will be on mid-shoot leaves. Thresholds for trees with sparse canopy and heavy crop load are lower than for trees with luxurious canopies. Generally, 1-3 adults per leaf will bleach around the midrib only; 8 per leaf will stipple the entire leaf and annoy workers. |
