Cotton-like specks can be controlled by oil


July 19, 1998

Q. There are little bits of white fluff growing all over two of my yew shrubs. I don't see anything moving around on the foliage. What should I do?

A.You're describing the white, waxy egg sacs of cottony camellia scale. The immature versions (known as crawlers) of this insect pest are feeding on the leaf undersides. They are not a serious pest, but their feeding may lead to an accumulation of excreted plant sap below the feeding sites. A black fungus, known as sooty mold, may then grow on the honeydew, detracting from the shrub's appearance. This scale can be controlled now with a 2 percent horticultural oil or, during the dormant season, with a 4 percent horticultural oil.

Q.Two rows of my snap beans came up great, but now the leaves are turning brown at the edges and curling. Upon close examination, I see lots of little, pale green things on the plants or hovering around them. Are they the problem? What should I do?

A. Those little green things are potato leafhoppers and they are producing the classical "hopper burn" symptom on your bean leaves. This is caused by a toxin in their saliva. Beans are a favorite host plant of this insect. Control them with an insecticide such as pyrethrum, rotenone, neem, soap or horticultural oil. Hit them early in the morning, when they are less active. Be sure to spray the top and bottom of each leaf.

Q. We're planning to power-wash our deck using a detergent. Then we want to restain the entire deck. I'm very concerned about the shrubs and perennial plants next to the deck. Do we need to cover them?

A.Yes. Cover all your plants right before washing and staining your deck. Use a plastic drop cloth. Remove the cover as soon as you're done to avoid heat damage to the plants. Keep the detergent and stain off the soil and adjacent turf as well.

Tips are provided by the Home and Garden Information Center of the Cooperative Extension Service of the University of Maryland. For additional information, call the center's hot line at 800-342-2507 or visit its Web site at

This week's checklist

Provide some type of support for your sweet corn, eggplant and pepper plants to keep them from getting blown down or damaged in storms.

To avoid burning plant leaves, sweep granular fertilizers off them. Liquid fertilizers can also burn foliage, particularly on hot, sunny days.

Leave snakes alone! They are important predators of rodents.

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