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Ron Smith answers questions about flowers, trees, gardens and shrubs.

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I have giant strawberry leaves and runners, but no blossoms. Last year, I dug out an area near the strawberries and dumped in peat moss, compost and manure. I thought this was a good idea. I’ve read that overfertilization could cause this problem. How do I undo this issue? (Denver, Colo.)

A: Undoing overfertilization is solved by leaching with water. It is too late for this growing season, so patience is needed. Do not fertilize between now and the next growing season.

Q: Last week, we had a windstorm through Ohio. My 3-year-old Norway crimson king maple was twisted and the trunk is split. However, the split isn't very wide. The split starts a few feet off the ground and goes up about 8 inches. The tree is sapping and drawing bugs. I put two wire ties around the tree so it wouldn't split more. I also mixed some Bayer Tree and Shrub Protection and poured it around the trunk of the tree. I really don't know what to do now. Should I wrap it or let it alone? I really like the tree and get many compliments on it because there are not many crimson trees in the neighborhood. I also have a 3-year-old Sun Valley red maple. Should I wrap that before winter? Thank you for your time. (email reference)

A: You have good intentions, but they are in error. Cut the loose bark back to where it is attached and take the ties off because they will do more damage than good if allowed to remain. Crimson king maple trees are thin-barked when young, so they benefit from being wrapped prior to the arrival of winter. Both species of trees should be pruned minimally throughout their lives by a certified arborist.

Q: I purchased a tradescantia blue and gold spiderwort plant. Since my purchase, I have been told that this is an invasive plant. I don't want to plant it if that is the case. However, I am not finding much information about the plant. Can I plant it? Thank you in advance for your information. (email reference)

A: Not true because this is a native plant of mostly wetland prairies, so they are not considered invasive. The only way something becomes invasive is when normal native competitiveness between species is knocked out of balance by an act of nature, such as a fire, or by man deliberately eliminating all other indigenous species.

Q: We are concerned about our tree. It was a little late with its leaves this spring but really filled out last week. Unfortunately, we had a terrible wind that stripped about 30 percent of the tree’s foliage. This was the only tree in the neighborhood affected. My concern is that the tree might be sick. We have had an unusually wet, cloudy spring. Will the foliage return, and do you think we should be concerned? The tree is 20 to 25 years old. (Colorado)

A: Hackberry trees are somewhat notorious for their dalliance at leafing out. Most trees that are the age of yours will have no trouble coming out with more foliage in two to three weeks. Everything should be OK.

Q: Last spring, I planted a multitrunked river birch (Betula nigra) in the front yard. The leaves on it were rather small when I planted it, but the nursery said the leaves were small because it had been in the shade. Otherwise, it looked healthy. I added a root-boosting product when I planted it and it seemed to thrive. However, this spring, the tree seems to be dead with the exception of new leaves coming up around the base. I cannot find any holes or indications of birch borer. Can I get a good tree if I let the new leaves at the base grow? I have two other birch trees in the yard that have done well for several years, so I think the site is OK. I live in extreme southwestern Nebraska. The tree is partially shaded from the hot afternoon sun and winds. (email reference)

A: While regrowth from the crown is possible, it will take an eternity for the tree to become anything worthwhile in the landscape. Perhaps you have the will and patience to work with this struggling plant while throwing aesthetics aside. For me, life is too short to wait that long. Another point is that the small leaves were not from the tree being in the shade. They were the result of a truncated root system. Shade-grown leaves are larger to capture as much light as possible. What you purchased was a stressed tree that had no more than a 50 percent chance of getting through the winter. It is your call. A river birch should make it where you describe as long as it isn’t planted too deeply or in heavy clay soil.

Q: I recently sprayed my lawn with 2-4-D. My neighbor is concerned that it may have drifted into his lilacs and tree rows. How long would it take to see signs of damage? Will his lilacs and trees survive? (Bismarck, N.D.)

A: The reaction would be within 48 hours of spray application in most cases. Also, the subsequent new growth may be distorted and misshapen. In almost every instance, the plants will survive unless a direct spray hit was made over all of the plants. We do not recommend applying herbicide whenever the wind speed exceeds 10 mph. Good luck on finding a day when that occurs.

Q: I am very frustrated with certain critters or whatever you want to call them. Last year, they gnawed on potatoes, ate the roots of the peanuts, some carrots and strawberry plants, and made mounds in my tomato cages. I can’t find an entrance hole. After the spring thaw, I found various tunnels and mounds, plus dead moles or voles. They had shorter tails and more fur than a mouse and are a little bigger than a mouse. I would like to know how to get rid of whatever they are. They are very destructive and causing a lot of damage to my yard and garden. Any help would be greatly appreciated. (email reference)

A: These very likely are voles because they are eating your veggies. You need to set traps with something that will tempt them, such as peanut butter. Keep it up so the critters don’t take over your garden. These usually are very shy animals that work from the cover of tall grass, weeds or woody plants. If possible, clear the area around your garden somewhat to provide greater exposure. Raptors in your area will take note and help you eliminate them. Poison can be used. However, I worry about the poison getting recycled through the food chain to the raptors or neighborhood pets that might come upon a body, consume it and then become poisoned or extremely sick as a result.

Q: What do you recommend using to treat an evergreen that is turning brown? (Kentucky)

A: I recommend that you find out first what is causing the evergreen to turn brown. Some browning of the older foliage, such as the interior branches, is normal. Anything affecting the current or past season’s growth is not. You can get assistance for making this determination from your land-grant university, which in your case is the University of Kentucky. As a start, go to to find an Extension Service agent in your county. The agent should be able to assist you or connect you with someone at the university who can.

Q: Some of my iris blossoms are not developing as they should and some are deformed. What could be the problem? (Oregon)

A: Bloom distortion as you describe usually is traced to thrips feeding on the flower buds or a virus. Generally, the thrip activity is the root of most of these problems. Once the symptoms are noted, it is too late to do anything. Next spring, apply a systemic insecticide to stop them in their tracks before they can cause a lot of damage.

Q: I went through your information on lilacs but didn't find the answer I need. Let me start by giving you a little background. I bought some gorgeous French lilacs. The blooms are large and a deep plum purple. I am wondering if there is any way to root these cuttings, which are about 9 inches long, including the flower. For now, I cut the stems at an angle while underwater and put them in a vase using cold tap water. Thanks so much for any help you can give me. (email reference)

A: Cuttings should be taken when new green terminal shoots are produced. They should be 4 to 6 inches long. Do not allow the cuttings to dry or else wilting and failure will result. The cuttings should be dipped in a rooting hormone, such as Indolebutyric acid. The hormone aids the rooting process. The cuttings can be placed in a media that contains peat, vermiculite and perlite. Each cutting should contain two to three nodes, which are the growing points where the leaves are attached. The leaves aid in rooting by producing carbohydrate for the rooting plant. The cuttings should root within three to six weeks. Be sure to mist the cuttings frequently. Once the roots appear to be extensive enough to support the plant without fussing over it with several daily mistings, gradually begin withholding the misting frequency to get it hardened off to the real- world environment. After a couple of weeks of withdrawal from this treatment, the freshly rooted cuttings should be able to stand on their own. Remember that cuttings will not root when they are into flower or seed production.

Q: I purchased several arborvitae shrubs two years ago. Last year, I had to remove four of them because of extreme yellowing and browning. This year, the same thing is happening to the replacement plants. I planted them in good soil and watered and fertilized according to directions. Can you help? I read on a website that I should apply lime if my soil pH is off. If so, how much lime do I apply? (email reference)

A: Something is definitely out of whack! Arborvitaes are among the most dependable and easy to grow woody plants in North America. About the only thing that will kill them that quickly is very poor drainage, too much water or they were planted too deeply. Up to a point, arborvitaes are somewhat pH indifferent. Arborvitaes grow well in alkaline soil where the pH is above 7.5 and in acid soil where the pH is below 6.5. If you know that the problem is not overwatering or being planted too deeply, I’d suggest getting the soil tested for nutrient, salt and pH status. Extremes in pH, such as 8.9 or 5.5, could cause some problems indirectly, but not as quickly as you describe. Contact the county Extension Service office in your state to get detailed information on where to send your soil sample. Go to to find your local contact.

To contact Ron Smith for answers to your questions, write to Ron Smith, NDSU Department of Plant Sciences, Dept. 7670, Box 6050, Fargo, ND 58108-6050 or e-mail

NDSU Agriculture Communication – June 8, 2011

Source:Ron Smith, (701) 231-7123,
Editor:Rich Mattern, (701) 231-6136,
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