The Q&A Archives: Holes in rhododendron leaves

Question: My older rhododendron leaves have large holes in them. What's chewing on the leaves, and how do I stop it? George Getz Bricktown, NJ


The damage is consistent with the feeding pattern of black-vined and strawberry root weevil adults, says Steven Kristoph, owner of Steven Kristoph Nursery, grower of more than 300 varieties of Rhododendrons and azaleas in Englishtown, New Jersey. Bothweevils have similar life cycles, overwintering as larvae in the soil around host plants such as rhododendrons, azaleas, hemlocks and yews, then pupating in spring. In June, the adults emerge and crawl up the stem of the plant at night and feed on the leaves, causing the characteristic notching you describe. This continues for about a month, with the weevils hiding in leaf litter during the day. Then the adults lay eggs near the base of the plant. The resulting larvae burrow into the soil to feed on the plant's roots, also causing considerable damage. There is usually one generation per year. If the feeding is only on a few leaves on each branch, just keep the plants healthy. They'll most likely outgrow any damage, advises Kristoph. For severedamage, introduce beneficial nematodes, which attack the larvae, around the base of the plant once the soil has warmed above 50 F and the larvae are present - late July in your area. For best results, apply nematodes on an overcast day and water them inwell.

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