Richard Nunnally’s Gardening Q&A

Q:We have beautiful lilacs that are attacked by Japanese hornets a couple times each summer. These huge hornets girdle-strip the bark from branches and trunks apparently to use for nest-building. They appear to be immune to Sevin applied to the bushes or directly to the insects. The only success we have had against the hornets is to ambush them with a direct shot of wasp and hornet spray while they are gnawing on the plant. We would appreciate any advice you have.

Answer: Sevin and hornet sprays may be the best options. As you probably know, Sevin doesn't kill them for several hours or a couple of days after they ingest it. Consequently, it will not keep the hornets off the lilac. They have to make contact with the Sevin to become infected. The hornet spray is more immediate but requires you to be on constant lookout. Fortunately, they feed on and strip the bark for just a few weeks. A more organic option may be to spray the hornets with insecticidal soap. Again, you'll have to spray it directly on them, as you do the hornet spray. As it dries on their exoskeleton, it causes them to dehydrate and die.

Most experts agree that although these hornets are a nuisance and can damage small twigs, they rarely kill the plant. Once their bark stripping is over, you can prune out the affected twigs, and the plant should produce new growth the following season.

Q:What suggestions do you have for controlling weeds and undesirable grasses in asparagus and strawberry beds? Crabgrass has also infiltrated the liriope in my borders.

Answer: I really don't like to use herbicides around home food crops. I'm afraid the best control for weeds in asparagus and strawberries is hand pulling and mulch. Asparagus is a little more difficult because you need to leave the ferns until winter. However, with strawberries, you can cut them down to about 2 inches tall after they finish bearing and then do a good job of hand weeding. Next, fertilize them and add a good layer of clean straw mulch. This is a great way to manage the weeds and to rejuvenate a strawberry bed. By the way, it's also a good time to thin your plants and give them away or start a new bed.

Again, asparagus is more difficult, because of the ferns. Many organic gardeners use rock salt every few years to control the weeds in the asparagus beds. This can be damaging if you use it too often or use too much. But it may help get the weeds under control for now. You can do a good job of weeding after you cut the ferns next winter and mulch them with clean straw, as well.

As for crabgrass in your liriope, you can call around to your favorite garden centers and see if they carry products such as Ornamec, Vantage or Grass-B-Gone. While all of these offer selective control, they will not hurt your liriope. However, none of them is registered for use around food crops.

Q:Is there anything we can do to discourage earwigs? Not only do they mutilate our day lilies in the garden, but they also put in many unwelcome appearances in the house.

Answer: Unfortunately, the main way to discourage earwigs is to remove the mulch from around the house. Mulch holds the moisture they need and allows them to feed on the decaying organic matter. You can treat the area with Sevin to kill them, but if there is a lot of mulch in the area or if it's near a wooded area with natural leaf mold on the ground, they will return.

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