Gardeners phone in a variety of questions

Hornets on lilacs and scab on pecans were mentioned by many of the gardeners who called Extension in September. Here are a few of the month’s questions.

Q. My lilac bushes are full of hornets and they are tearing up the bark. What can I do? — T.A., Lynchburg
A. This is the time of year when giant European hornets chew the stems of lilacs to feed on the sap and remove bits of bark for building their nest. To be safe, stay away from your lilac bushes for a while. These hornets can be very aggressive. Branches killed by hornets can be cut out of the plant later.

Q. The ground under my pecan tree is covered in pecans. They dropped off earlier than usual and all of the shells are empty. Inside is some rotten material. Never before has this ever happened to my pecan tree, not in 30 years. — E.P., Lynchburg
A. Several gardeners called me about this situation over the span of a week or less. More than likely the abnormally wet conditions earlier this year promoted a disease such as pecan scab. You can collect and dispose of the bad nuts to reduce the chance of more scab next year.

Q. I have some liriope I need to get rid of. How can you eradicate the plant? — S.D., Lynchburg
A. The quick and easy way to remove clump-forming liriope from your yard is with a shovel. Two or three applications of glyphosate (Roundup, Killzall, etc.) over the course of a summer also does the job nicely. The latter method is the preferred one where sod-forming liriope spicata is established. This plant is like wiregrass, with vigorous rhizomes.

Q. There are some daylilies in my yard I want to kill. What works best on these plants? — C.R., Buckingham
A. Spraying them monthly or so during the growing season with glyphosate is effective. You could also dig them out of the ground and then run a rototiller or lawn mower over the area now and then. A clump of daylilies can grow up through a fresh layer of asphalt, so be prepared for a struggle.

Q. By accident I sprayed one of my azaleas with Roundup. Is there anything I can do to save it? — C.N., Lynchburg
A. Unfortunately there is no antidote available. Pruning clippers might have helped, however. Immediately cutting off the branches sprayed with Roundup would have prevented the chemical from translocating back into the root system.

Q. What might have killed a big old chestnut oak? I recently pruned a few branches out of the tree for one of my customers and then it died. Is there a connection? — W.W., Lynchburg
A. A likely cause of the problem is bark beetles. They are attracted to oaks which have been stressed out by the environment. These beetles eat up the tree’s sap wood and leave a dusting of powdery sawdust on the bark to indicate their presence.

- Davis is an Extension Agent for the Virginia Cooperative Extension. He can be reached by calling 455-3740.