August 23, 2001

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I have several peony plants I would like to break up. When would be a good time to do this for transplanting, and how deep should they be planted? Also, I have some fern leaf peony plants that are several years old but they never do anything. They come up in the spring, grow about 12 inches, maybe get a few buds but never develop. Could it be that they are planted too deep? The buds that do appear are very tiny and turn black before opening into flowers. (Jamestown, N.D.)

A: Late summer (August) is the best time for division and transplanting. This gives the roots plenty of time to re-establish prior to winter. Your description of fern peony problems is exactly symptomatic of planting too deep. Try pulling an inch or so of soil away from the crow to see if that improves things next spring.

Q: We planted a hackberry three years ago but have yet to see it produce fruit. Is this unusual? The tree trunk diameter is a bit over 1.5 inches. (E-mail reference, Ottawa, Ontario, Canada)

A: I have been asked about apples, cherries, apricots, and plums fruiting but never hackberry fruiting in 16 years of answering horticulture questions. It will bear fruit, most likely, when it is mature enough. That would be about five or six years from now, as a guesstimate. If the tree could have an emotional response, I am sure it would be flattered to have an inquiry about it fruiting, since that is not a major attractive characteristic about it.

Q: I just removed two maple trees from my front yard because they were lifting my sidewalks and driveway. I was wondering what kinds of shade trees do not have roots that do this. I also do not like top roots, as I am picky about my grass. (E-mail reference, Nebraska)

A: If you are really picky about your grass, then you shouldn't grow trees in it. Other than in natural Savannah landscapes, trees and grass don't go together. If you are going to grow trees in a landscape then you have to give them somewhat of an open area around the trunk for the increase in size and for the eventual development of flange roots that provide some basic support for the tree as it gets larger. Maples and poplars are noted for developing surface roots in the turfed landscape. You might try the Redmond linden or one of the cultivars of honeylocust that are available in your area. They make good street shade trees with a minimum of surface disruption.

Q: I started to eat apricots, and I would love to know the vitamins and nutrients that are in them. Are they good for the hair, nails, and skin? (E-mail reference)

A: Even though I am a horticulturist and not a nutritionist, I have the same interest as you, and believe it or not, some very credible references. Fresh apricots contain 85 percent water. Each 100 grams (about 3.5 oz) of fresh apricot provide 51 calories of energy, 319 milligrams of potassium, 2700 International Units of vitamin A, and only 1 milligram of sodium. Fresh apricots also contain 0.4 gram of protein, 0.1 gram of fat, 4.9 gram of carbohydrates, 0.2 gram of fiber, 3.0 milligram of calcium, 5.7 milligram of phosphorus, 3.5 milligram of magnesium and traces of iron, zinc and copper. Everything else is in relatively small amounts-- vitamin C, riboflavin, thiamin, niacin, and a modest level of folic acid. Just about all fresh fruits are good for the hair, nails and skin. Besides all this technical stuff, they, along with their cousins, peaches and nectarines, are simply delicious to eat, and make excellent pies and jams.

Q: I have a 4-year-old poplar and this summer the leaves have been turning yellow and falling off. They have small dark green spots on the underside that looks like a fungus. The leaves started falling from the bottom of the tree and have worked about a quarter of the way up the trunk. This is the only tree in my backyard (new development) and it gets plenty of water, being in a low spot of the yard. Any help you can provide in what is causing the leaves to drop would be helpful. (E-mail reference, New Jersey)

A: Be thankful that the problem showed up only after four years, because then you can be motivated to replace it with something more worthwhile than a poplar tree. I have an entire book dedicated to diseases of poplar trees. The one in your yard must be a requirement that the housing contractor had to install to consider the job complete. I strongly suggest that you get the tree out of there and visit a local nursery or garden center to get a replacement. There are lindens, birches, Japanese maples, silver maples, sugar maples, Norway maples and even DED resistant elms that would be a better choice, plus a lot more. Poplars would only plague you with surface roots, invasive roots, breaking branches, and a whole book full of diseases and would not add value to your property as it matured, if it lived long enough to do so!

Q: I have white spots on my tomatoes. When I bring them in the house, after a few days it looks like little holes in the tomatoes where the white spots were. What is wrong with them? (Williston, N.D.)

A: My best guess is that it is a disease like bacterial speck that attacks fruit in this manner, leaving black dots or holes all over the fruit. While unsightly, they can be cut out in most cases and the fruit still consumed. Try to avoid water splash on the fruit and foliage, and take care when working the garden that the disease doesn't get spread from one plant to another. Spraying with a fungicide at this time would be of no help. Cleaning up the debris this fall, rotating the planting site, and selecting resistant cultivars are the best approaches to preventing tomato disease.

Q: This summer we planted a row of bare root villosa lilacs that started to bloom almost immediately. The plants are 3 to 4 feet tall. They looked great until this past week when the tips of many of the leaves started to turn brown. We watered the plants extensively in the beginning, and lately we have had a lot of rain and it has been very humid. We have heard that high humidity can cause mildew on lilacs, but there is no mildew that we can see on the leaves. What can we do to keep them healthy? ( Lake Mille Lacs, MN)

A: At this writing, you are a little early to be worrying about powdery mildew, which is not toxic to the plants anyway. I am more concerned with your leaf tips turning brown. The description sounds exactly like the common pathogen Phytophthora cactorum, aka lilac shoot blight. It is the result of a spring that has been too wet and the soil not being able to handle the excess water.

Q: When we bought our house three years ago there were four large hydrangea bushes along the east side of our garage, which also has a huge pine tree for shade. The bushes grow so large that they must be staked. We have never pruned them as we weren't sure when the best time was. They have huge leaves and very long flower heads that are an off-white and pink. I have never seen anything like them in books or in nurseries. Is it possible for you to tell us their name and how to take care of them? We live in the southwest part of Ohio. (E-mail reference, Ohio)

A: Thanks for telling me where you live. It helps me to focus on what the plant might possibly be, and in this case, I think it might be the oakleaf hydrangea ( Hydrangea quercifolia). If I am correct, it should be pruned right after flowering, generally in early August depending on your location and microclimate. I wish they were hardy here in North Dakaota. We had many beautiful cultivars on the Ohio State campus when I was there in the '70s.

Do you have a gardening or houseplant question? Write to Hortiscope, Box 5051, NDSU Extension Service, Fargo, ND 58105 or e-mail to Ron Smith at ronsmith@ndsuext.nodak.edu. Note to e-mail correspondents: please identify your location (city and state) for most accurate recommendations.

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Source: Ron Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
Editor: Gary Moran, (701) 231-7865, gmoran@ndsuext.nodak.edu