The root of oak's problem


Garden Q&A


Our transplanted oak did well for two to three years, then last year leaf-out on the top third reduced significantly. This year, more than half is leafless, with no visible pests or diseases. The soil is clay, but we prepared a large planting hole with highly improved soil.

Dying from the top down points to a root problem. Though adding large amounts of organic matter to backfill soil seems like a great idea, in a clay soil the organics act like a sponge. When it rains, the amended soil absorbs water readily, but then the water cannot disperse into the surrounding clay quickly and just sits in the hole. (Clay particles are very minute. It takes a long time for water to penetrate between them.) Consequently you get a "bathtub effect." Your tree roots may have sat in a hole full of water and drowned. And if you didn't get a lot of rain the roots would have grown primarily in the amended planting soil and not grown out into the native soil. Next time, when planting a tree in heavy clay soil, work in some compost over a much larger area.

Is it all right to use the same support device to grow green beans and cucumbers and not suffer some type of cross-pollination? What other plants risk cross-pollination in a simple home garden?

Different vegetable species typically cannot cross-pollinate, so you're safe with the beans and cucumbers. Cross-pollination that occurs, for instance between summer squash varieties, would not affect this year's planting. It would only show itself if next year you planted the saved seeds from this year's cross-pollinated plants. The resulting plants would not grow true to the parent plant. The exception is corn. Do not try to raise Indian corn, popcorn and sweet corn in the same plot. This summer's crop will be all mixed up and none of it will be sweet!


Once a week, lightly fertilize tomato and pepper plants growing in containers.

Spot-treat broad-leaf weeds in the lawn with a labeled herbicide. Avoid spraying the entire lawn.

Jon Traunfeld, regional specialist, and Ellen Nibali, horticulture consultant, work at Maryland Cooperative Extension's Home and Garden Information Center, which offers Maryland residents free gardening information. Call the center's "hotline" at 800-342-2507 (Monday through Friday, 8 a.m.-1 p.m.) or e-mail plant and pest questions through the Send a Question feature at

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