Garden Q&A: Leaves fall prey to yellownecked caterpillar

Leaves have been stripped from our river birch trees, but we can't seem to find the culprit. We looked under leaves, and my husband searched with a flashlight at night. What should we do?

In late summer-early fall it’s common for a mob of caterpillars to strip leaves from a branch here and there, then move on or pupate. One such gregarious bunch is the yellownecked caterpillar, known for arching into a U when disturbed. As caterpillars grow bigger late in the season, they can strip a branch faster. Bare branches seem to appear overnight. Caterpillars can be manually removed and destroyed or sprayed with insecticidal oil. The good news is that by late summer mature trees have had plenty of time to carry on photosynthesis and build up carbohydrate reserves for next year. Losing a few leaves doesn’t hurt them. Trees actually grow extra leaves for just such situations. You do not need to prune off the bare branch.

Looking forward to cooler weather and putting the garden to bed for the winter. Is there anything special I should plan on doing to get my new raised vegetable beds ready for cold weather and next year's growing season?

Here is a list of tasks from Grow It Eat It on the HGIC website. Putting the garden to bed properly in the fall gives you a jump on next year's growing season.

Test your soil. (Click the soil testing icon on the HGIC homepage.) We can't stress this enough! Adding amendments to your soil in the fall ensures that they are available in the spring for optimum plant growth. When lime is needed, it requires time to change pH. It’s also a good time to add compost.

Clean up plant debris. Pull up all dead and unproductive plants and add them to your compost bin.

Remove diseased or insect-infested plant material off-site. It can shelter overwintering stages of pests. This reduces the potential for disease problems next year. Bag this debris and put it out in the trash--not in the compost pile. Only very hot composting will kill off potential problems.

Don't leave the soil bare. Cover soil with some type of mulch to prevent erosion and inhibit weeds. Shredded leaves are good and less likely to blow away than whole leaves. They can be worked into the soil next spring or seedlings can be planted through them. Planting a cover crop is even better for your soil. Search ‘cover crops’ on the HGIC website.

University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click “Ask Maryland’s Gardening Experts” to send questions and photos.

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