Persea Mite
Oligonychus perseae
A tiny spider mite that is a common pest of avocado, feeding in silk-covered colonies on the underside of the leaves. Heavy feeding causes brown spots and premature leaf drop that can expose fruit to sunburn and lower the next season crop, though backyard trees often tolerate it.
🔎 How to spot it
Adult females are about one fiftieth of an inch long, oval, slightly flattened, and greenish or yellowish with two or more dark blotches on the abdomen. The mites feed mostly beneath roundish patches of silk that look like small silvery blotches on the lower leaf surface. A hand lens shows the mites and eggs within these nests.
🥀 Damage it causes
Feeding causes discrete circular brown to yellowish spots that first appear on the lower leaf surface, with each colony under its own dense patch of webbing. As mites become abundant, the spots multiply and the leaves drop early, which can let sun reach and burn the fruit and reduce yield the following season. Hass and a few other varieties are the most susceptible.
🛡️ Prevent it
Keep trees well watered and avoid drought and dust stress, which favor mite buildup, and avoid broad-spectrum insecticides that kill the predatory mites and insects that hold persea mite in check. Monitor the underside of leaves through the warm season for the silvery webbing patches. In home gardens the mite can often simply be tolerated.
🧯 If it is already here
A forceful spray of water to the underside of leaves knocks down mites and webbing on small trees, and narrow-range horticultural oil can be applied to the foliage where feeding is heavy. Conserving natural enemies, including commercially available predatory mites, often brings populations down without further action. Avoid repeated harsh sprays that flare the problem by killing predators.
💡 Good to know
Persea mite passes from egg to reproductive adult in about two to three weeks at warm temperatures and has many overlapping generations a year. The silvery silk patches with brown spots underneath separate it from other leaf problems on avocado. Residential trees usually survive the feeding, so tolerance and predator conservation are the first response.
🌱 Plants it attacks
3 plants in the library can be attacked by this pest
For educational and informational purposes only. Pest control advice is general guidance drawn from university cooperative extension sources; always identify a pest positively and read and follow the label on any product before use, especially around food crops, children, and pets.