Also described a “salt deposits” or “sugary specs” and followed by yellowing leaves, black mold spots and defoliation. What’s going on?
Sometimes called jumping plant lice, psyllid feed on a variety of plants. Both adults and nymphs feed by piercing the leaf surface to extract cell sap, and excrete “honeydew”, a sweet sticky residue that may attract ants or mold. When I first saw these white deposits, they appeared to be insect eggs, but others have described them as a crystal-like sugar deposit.
You may be familiar with the term honeydew as related to aphid infestations, a sweet excretion loved by ants. In fact, it’s believed that ants protect and cultivate aphids in order to harvest the honeydew. Psyllids are part of a group called Sternorrhyncha that includes aphids, scale insects and whiteflies.
Although a psyllid infestation is rarely lethal for the tree, it obviously takes its toll in the form of leaf loss, virus infections and, well, reduced garden aesthetics. Here are some measures you can take to control the infestation:
- Spray the leaves daily with water to knock off honeydew and psyllids. If performed diligently this can minimize the infestation, but psyllids can fly away and come back.
- Spray the complete tree with Neem oil. Psyllids hide in between branches and nymphs like the back side of leaves, so complete coverage is best. Neem oil is practically non-toxic to birds, mammals, bees and plants. Neem oil is slightly toxic to fish and other aquatic organisms. Azadirachtin, a component of neem oil, is moderately toxic to fish and other aquatic animals. It is important to remember that insects must eat the treated plant to be killed. Therefore, bees and other pollinators are not likely to be harmed.
- Biologic control with parasites and predators. Important natural enemies of psyllids include lady beetles, lacewing larvae, predaceous bugs, Leafhopper Assassin bugs, and tiny parasitic wasps.
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