ASK THE GARDENERS. Questions and Answers.
Q For several years now, I have noticed a frothy formation on the tips of weeds which surround our pine trees. My kid brother and I used to refer to it as ``frog spit.'' This past spring I noticed many of these small patches of bubbly white foam on new tips of the pines. Upon examining them I found soft, small green insects inside. I blush to say I never had bothered to find out the correct name of this formation, nor do I know if the pest inside it is harmful. Some pine tips did appear to be off-color. Is there a nontoxic way to get rid of the insect? J.F. Fredericksburg, Va. The nymph stage of spittlebug (which is what you saw) makes its foamy hiding place from extracted plant sap. They consume such a small amount, however, that they are not considered pernicious pests. Being sure plants are well-fed, watered, and cared for is a deterrent.
A simple method of getting rid of them is to direct a forceful stream of water on them. This flushes off their covering, causing them to fall on the ground where they cannot survive. Q A few months ago, the tip of a branch on my 10-year-old rhododendron started wilting. I sprayed with Benomyl, but the branch continued wilting so I cut it off. Others have done the same and I had to remove them. How can I stop the wilt? H.M. Richmond, Va.
Your rhododendron has borers. Small, half-inch, clear-wing black moths (with yellow bands on their abdomen) lay eggs on the tips in the spring, which hatch out into larvae that bore into shoots.
Benomyl is a fungicide -- not effective against insects. Chemical insecticides are of little help.
Inspect your shrubs daily and destroy infested branches immediately to reduce population.
Some friends tell us they have repelled the moths by spraying their shrubs the first week of May and of June with a solution of antitranspirant (e.g. Wilt Pruf) to which has been added a tablespoon each of nicotine sulphate, garlic juice, and hot pepper sauce.