Richard Nunnally’s gardening column

Q:Last year we lost a 7-year-old golden raintree. As I was cutting down the dead trunk, I noticed a series of white spikes about an inch long sticking out. The spikes were about the size of a toothpick and I assumed it was compacted sawdust or some kind of insect excrement. Now I have found the same kind of spikes on an 8-year-old brown turkey fig tree. Any idea what kind of pest is causing this and if there is any treatment?

Answer: What you have is a relatively new pest in Virginia called the Asian Ambrosia Beetle. According to Debra Martin, with the Virginia Department of Agriculture and Consumer Services, the beetle is a serious problem and has become quite prevalent in the past few years.

Martin said April and May are prime times for spotting the toothpick projections. As you suspected, those spikes are made of the sawdust and sap that develop as the larvae work into the tree. After you first see the spikes, she recommends leaving the tree as it is for three or four weeks to act as a trap tree. These insects apparently send out some type of attractant that brings other beetles to specific trees. At that time you should remove and destroy the trees. She indicated that the best way to dispose of them then would be to cut and burn or bury them, allowing you to greatly reduce their original numbers and prevent future generations.

She said healthy trees and shrubs can survive a light infestation, but will require monitoring for future signs of the beetle. Pyrethroid insecticides can be used as a preventative once the beetle's presence has been observed, but it will not kill beetles already inside the trees. She also suggested your best course of action against this pest is to concentrate on reducing stress to the trees, like drought or mechanical injury, which may help them outgrow future attacks.

Q:I have an established planting of red tips along my property line. These shrubs are about 15-20 feet tall and provide very nice privacy from the neighbors. They do not appear to have any disease, however the lower limbs do not have as many leaves as the tops of the shrubs. When can I prune them? Is there something I can spray on these shrubs that will help them resist the disease that is so prevalent in this area?

Answer: Red tips are actually wonderful plants, until they get the leaf spot disease. The best time to prune them severely is early March before they start producing new growth. Research has shown that heavy pruning during the late spring and early summer stimulates very tender new growth which is extremely susceptible to the fungus. Since yours have never had the disease, I wouldn't prune them at all this year. It would be better for the plants to prune them next March.

There is a fungicide that can be used to help protect the red tips from the fungus. However, it has to be applied when the new growth is developing. The label calls for three treatments at 10-day intervals. According to the Pest Management Guide from Cooperative Extension, several fungicides can be used to help manage the leaf spot, including: Captan, Daconil, Cooper fungicide, 3336 fungicide and mancozeb. Your favorite garden center will surely have one or more of these.

Q:We have a row of Leyland cypress trees near the back property line of our lawn. They are in the neighborhood of 35 feet tall. Recently, one fell over and another is leaning. We would like to cut approximately one third from the top of these trees to prevent them from falling. Would the trees live if we were to cut back that much?

Answer: Like many in central Virginia, your Leylands suffered as a result of this winter's snow. While they will survive your cutting them back, they will not regain their natural shape.

Richard Nunnally is a freelance writer and host of WCVE's monthly gardening show, "Virginia Home Grown." He can be contacted at .