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Holly Leafminer
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Q: I have two lovely American hollies (Ilex opaca). Every year, their leaves are disfigured by leaf miners. Can I do anything to prevent this?A: There are several species of leaf mining flies that attack holly foliage. The native holly leafminer spends the winter as a larva inside the leaf. They pupate and hatch out as adults, just as the shrub starts to put on new growth in the spring. We have one generation a year that coincides with tender new growth on American hollies. Control options include picking off mined leaves before May and disposing of them in the trash or by burning. This removes the overwintering larvae and keeps them from becoming adults and laying eggs in the new growth. Otherwise, insecticide application should be made to protect that new growth. Insecticides labeled to control native holly leafminer include BioNeem (azadirachtin), Sevin (carbaryl), Bayer Advanced Rose & Flower Insect Killer (cyfluthrin and imidacloprid), and Bayer Advanced Tree & Shrub Insect Control (imidacloprid).
If these hollies are very large, it may be a good idea to hire a certified arborist or a licensed pesticide applicator who has the equipment and training to spray them thoroughly and safely. Another option is to use Bayer Advanced Tree & Shrub Insect Control because it is mixed with water and applied by watering the soil under the hollies. This is a systemic product that is absorbed by the roots and translocated up to the branches and leaves. It provides good control and cannot be washed off by rain. It is easy for home gardeners to use and much safer than spraying because you are less likely to come in contact with the mixture. It also avoids the risk of having the product drip on you, which can happen when you spray a plant bigger than you. |
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