Q:I have about 17 peonies in a garden. During the second half of every summer, they get black spot. This year, some also got powdery mildew, even though there was no over head watering except by rain. We water with a soaker hose, and the afternoon sun is slightly diminished each year by continued growth by large pine and oak trees. How do I prevent black spot and powdery mildew?

Q:I have a large area of English ivy that I have treated with varying success with two herbicides. The waxy coating on ivy leaves seems to reduce the effectiveness of the spraying. Can you suggest a product that will eradicate this plant? Answer: The only success I’ve had is to cut it all off at the ground and when it starts to grow back, spray it with glyphosate. As you discovered, the mature leaves are not receptive to any herbicide. However, the new young leaves will absorb it and send it to the roots.

Q:Our Knock Out roses were a huge success this summer. However, I have no clue how to prune them. Should they have been pruned in midsummer to encourage more blooms? What should I do to them now? Answer: One of the great fea tures of Knock Out roses is that they don’t require a lot of pruning. I know several landscapers who believe you shouldn’t prune them at all. They tend to continually produce new growth and new blooms throughout the season. Since yours were so successful, I wouldn’t suggest changing very much. I prefer mine to stay under 5 feet tall, so I cut them back in mid-June. If you have room to let them grow, you’ll just get that many more flowers. Should they wind up looking leggy at the end of the season, cut them back in late February to shape them up.

Q:My lilac is leaning helplessly. It is at least 20 years old and has been blooming nicely. Two or three years ago, it started leaning. I tried to tie it to a stake; but it keeps leaning a little more as time goes by. I now have a heavy wire pulling it toward a steel stake. Is it losing its roots? Will it ever do any better? Should I cut it way back?

Q:I had such a hard time keeping the grass out of my garden this year. To prevent the same thing next year, can I spray the whole area with a grass killer and destroy all that grass? Answer: You can. However, if the weedy grass was crabgrass, it will die on its own with the first frost anyway. The issue you’ll have to deal with next spring will result from the seeds that crabgrass has been dropping for the past month or so.

Q:Is there a way to eliminate crab grass without killing other grass? Answer: There are some post-emergent crabgrass killers that will kill crabgrass and not your fescue. However, they are most effective early in the summer when the crabgrass is still immature. Even back in early September, it was probably better to ignore it, knowing it will die with the first frost. You can aerate your soil and plant new fescue seed right over the existing crabgrass. By the time frost kills the crabgrass your new seedlings should be up and growing.

Q:On a recent edition of Virginia Home Grown, you mentioned that you use leaves as mulch for your plants. How do you shred your leaves, and do they really need to be shredded? Answer: I shred most of my leaves with the lawn mower. Also, I get a lot of leaves from my neighbor, who gets hers up with a riding mower with a bagger. However, I don’t think you need to shred all of them before you use them. Start with a base layer of unshredded leaves, as long as you mat them down good and cover them with shredded leaves. After a few rains, they’ll settle in on their own. I can’t bring myself to buy mulch when I get all these leaves for free.

RICHARD NUNNALLY Q:My yard is looking dreadful. What should I do to rid the yard of the crabgrass? My guess is that I should have done a second application in early summer. Now I want to winterize and reseed and rejuvenate the fescue. Answer: Unfortunately, there is no permanent cure for crabgrass in a fescue lawn. You’re right, in cases of heavy crabgrass it is a good idea to make a second application around June 1st.

Q:I am having some select timber cut on my property. Some of the hardwood that I am leaving has been skinned up with the bark knocked off. What can I put on it to help save the tree from disease? Answer: Tree wound dress ings are no longer recommended. The only thing you can do is try to cut the jagged edges of the wounds to a straight, clean edge. Also, cut the edge near the bottom of the wound to a point to allow water to run out rather than get trapped in uneven, broken bark. If the trees are otherwise healthy, the wounds are small enough and you make these repairs as soon as possible, the trees should repair themselves.

RICHARD NUNNALLY Q:I use lots of mulch that I get from the city’s mulch pile. Some of my neighbors warn me against using it on beds near the house because they claim it will attract termites. Is this true? I have used this mulch for years and have never seen any bugs in it at all. Answer: Your mulch should be fine. Normally, mulch available from localities has been double shredded. As a result, there shouldn’t be enough solid wood left in the material to give termites a place to feed. Most of us already have termites in the soil in our yards. They are part of the natural process to break down dead wood. They are as natural in the Richmond area as ants. That’s why we have our homes treated to repel and control the termites.

Q:I have a shady area in the backyard underneath some pines and gum trees. Late this spring, I planted some shade-loving perennials, grasses and hostas in this area. Now I have some clover and wild strawberries growing as a natural ground cover. Should I let them proliferate and add to the foliage or weed them out? Answer: If you like the natural look of the clover and wild strawberries, I would leave them alone. Clover is a wonderful pollen-producing plant for bees, as well as a source of nitrogen for your other plants. Since neither of these are climbers, they should provide a good natural ground cover.

Q:I have two fruit-bearing trees—a fig and a plum. However, I never get any fruit because of the squirrels. I’ve tried a fake snake, but that only drove the birds crazy. Can you recommend anything to keep the squirrels out of my fruit trees? Answer: Squirrels can be quite a nuisance for gardeners. They can get under the nets that are sold to protect fruit from birds, and they don’t scare easily. Some people have resorted to tying aluminum pie pans from strings on several limbs as the fruit gets near harvest stage. The reflections can keep the squirrels away for a few days.

Q: I have two large butterfly bushes that need to be trimmed. When is the right time to do this and how much can I safely cut? Answer: You can trim back butterfly bush anytime now. You can prune them all through the summer as the old blooms begin to fade. By removing the old blooms you’ll stimulate more new growth and more new blooms. Butterfly bush should continue to flower right up to the first frost.

Q:This spring, I was given a dogwood standing 6 feet tall and 2½ feet wide, which I have planted beneath a large hawthorn. It seems to be a happy plant. However, I just realized that its projected size is 20 feet by 20 feet. My lot is quite small. Will I be able to contain this dogwood with pruning? A plant that grows to about 10 feet by 10 feet would fit better in my yard.

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.