Fall webworms, now appearing on branches, should not do any lasting damage to trees

Backyard Q&A

In The Garden

September 12, 2004|By Jon Traunfeld and Ellen Nibali | Jon Traunfeld and Ellen Nibali,Special to the Sun

I noticed a worm construction on the branches of my London plane tree. The branches are too high for us to reach with a stepladder, and we're in our 60s. Will the tree die?

The fall webworm, caterpillar of our native tiger moth, has two generations a year, with the late summer-fall one most noticeable. The web resembles that of the tent caterpillars, but webworms build their nests on branch terminals, whereas tent caterpillars build in tree crotches. Webworms feed inside their webs. They do not spread disease and, in fact, are a food source for over 75 species of predators and parasites (the good guys) that normally keep their population below damaging levels.

If you can reach the nests, the simplest solution is to break up the web with a pole and let predators feast on the caterpillars. You can also prune out webbed terminals or remove with a pole or by hand. Drown caterpillars in a bucket of soapy water. Although webs look unsightly for a while, they disintegrate over the winter. If you can't reach the nests, webworm feeding should have no lasting effect, because your tree had all summer to produce plenty of food reserves.

The perennial garden in front of my house, including balloon flowers and geraniums, bloomed nicely but looks a bit ragged now. I'd love some advice on how to make it look a bit more kempt: I'm unsure of how much to cut back.

Keep your perennial bed well groomed through fall by cutting off any dead material, especially diseased parts. Yellowing stalks and leaves on their way out can be removed, too. Never remove the vigorous green base that is next year's basal foliage. Some perennials bloom and have green foliage well into fall, so don't remove healthy foliage yet. Consider leaving spent balloon flower to enjoy its attractive yellow fall foliage. Perennial geraniums often have red fall foliage worth leaving. Flowers with seedheads that birds relish or with an interesting winter silhouette, such as black-eyed Susans, can be retained all winter.


1. Time to scrap your old gas-powered lawn mower? Consider buying a battery-powered mower, designed for lawns up to a third of an acre. You'll save money in the long run and contribute to a healthier environment.

2. Corn salad, arugula, spinach, sorrel, kale and many Asian greens can be sown in empty garden space. These crops will produce food for the table this fall and come back in the spring.

3. Water all fall-planted shrubs and trees regularly to help them establish healthy root systems.

Jon Traunfeld, regional specialist, and Ellen Nibali, horticulture consultant, work at the University of Maryland Cooperative Extension's Home and Garden Information Center. The center offers Maryland residents free gardening information and answers to plant and pest questions. Call its hot line at 800-342-2507 (Monday through Friday, 8 a.m.-1 p.m.) or e-mail questions to www.hgic.umd.edu. (You can also download or order publications and diagnose plant problems online.)

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