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

By Ron Smith, Horticulturist

NDSU Extension Service

Q: Our 12-year-old weeping birch tree appears to have died because all the leaves have turned brown. Do you think it is a goner or should we wait to see if it revives next year? What do you think caused this? The leaves started turning brown early this summer. (email reference)

A: It certainly sounds like your birch is a goner and the disease that likely caused its decline could be a vascular wilt, which you can do nothing about once it gets started. Sorry to be the bearer of bad news because this is one of my favorite tree species. I have owned and admired one for the past 27 years on my property. If your area was under water or the soil saturated last year from the flooding that took place, this could be where the problem got started.

Q: I have grown daylilies for years. This year, something strange happened. On some plants, one or two of the stalks turned brown, had small buds and then died. However, the other stalks on the same plant flowered perfectly. Do you think they'll come back next year? It's been so dry that I had to water several times. I watered over the top of the plants instead of at the bottom. Would that be a problem? I am in a quandary trying to figure out is wrong. (Hitterdal, Minn.)

A: Daylilies have been hit this year by a virus and fungal disease. In some cases, both problems are on the same plant. The leaf streak fungus appears to be the most common problem, with the virus a close second. These diseases are weather-related problems. The virus spreads because the insects that transmit the virus have not been controlled adequately across our region because of the uncommonly mild winter we had this past year. In most cases, the plants will recover. When the symptoms show up, I suggest removing the infected foliage and spraying with a fungicide to protect the plantings that have not shown any symptoms. Early virus protection is not available, so monitor the insect activity on your plants and take the appropriate action at that time.

Q: I am interested in planting two red maple trees. The trees would get full sun behind my home. The local nurseries here on the eastern shore of Maryland are very eager to sell me anything they think I need. Because these two trees will be used to shade my home, are red maple trees the best choice for my area? If you have any ideas, I would very much like to hear them. I am not a tree expert by any means. When the builder built the house, the first things to go were all the trees. (email reference)

A: A red maple is a beautiful tree, but there are all kinds out there. With trees, we refer to them as cultivars, and each cultivar has particular characteristics. For example, some are more upright and some have deeper red fall color. You need to contact the local University of Maryland Extension Service agent in your county to get proper guidance. Go to and click on your county to get someone to make a recommendation or two for you. Local good advice is better than me giving it to you from a thousand miles away. Get back to me if you have any unresolved questions or concerns.

Q: What can I do with my Russian sage plant? I like the fact that it blooms all summer. What I don't like is that it produces a lot of sprouts and spreads out of control. Is there some way to control these sprouts without killing the whole plant? (email reference)

A: You can insert a physical barrier around the plant or use Sucker Stopper, which is expensive. Sucker Stopper will kill the growing tip without killing the plant. Another solution is to dig the sprouts out with a spade and bare hands. Yours must be a very vigorous plant because I don’t have problems anywhere to that extent. When something shows up where I don’t want it, a sharp jab with a sharpshooter spade does the trick for most, if not all, of the season.

Q: It almost looks like a rodent of some sort took a bite out of a tomato. That was my first reaction. A gentleman from Cooperstown brought it in and heard a friend of his in town had the same problem. He stated that this tomato was more than 12 inches off the ground and in with a bunch of other tomatoes. (email reference)

A: What you are seeing is blossom end rot, which is not uncommon with the first tomatoes coming off the vine. It is caused by a calcium deficiency while the fruit was forming the final cells at the blossom end. The cells broke down, so a secondary decay moved in. Cut it out because the rest of the fruit is edible but not pretty to look at.

Q: I enjoyed reading your advice column about plum trees. However, I still have a few questions. The birds and squirrels are eating all of my plums before they have ripened. Can I pick these plums before they are ripe, and will they continue to ripen if I bring them in the house? Also, my shiro plum tree has some kind of disease or insect issue. The leaves are green, but many leaves are covered with small, round holes. What can I do to fix the problem? (Portland, Ore.)

A: In some cases, if the plums are mature but not ripe, they will continue to ripen once picked. Unlike fruits, such as grapes and strawberries, they will continue to improve in flavor after they are picked. Your other problem sounds like shot hole disease. Treatment is needed to keep it from spreading. I encourage you to contact your Extension Service county agent in the Portland area to get an accurate diagnosis of the pathogen and recommend a treatment. Go to and click on your county to get the needed assistance.

Q: I purchased a tree this spring that seems to be getting new and larger leaves. However, some of the leaves are turning yellow and have brown edges. I also have noticed that the main trunk at the top where it had been cut from the nursery has turned a darker color on one side and seems to be dried out when I scrap the bark. I can't tell if I'm over or underwatering the tree. (email reference)

A: The problem could be due to overwatering, being planted too deeply or both. I don't understand why the nursery where you purchased the tree thought it necessary to cut the top of the tree. This practice is discouraged because it removes valuable foliage needed to assist the tree in getting established. If it needs to be cut back, it can be done after becoming established in the landscape for a year or two.

Q: I have problems with zucchini plants this year. Ours start growing beautiful little zucchinis, but then they shrivel or turn brown on the bloom end. Also, the leaves are turning brown a little bit and feel dry and crispy. We have fed it some food heavy in nitrogen a few times. That seemed to help a little bit, but now the same thing is happening. We have a plot out by Yunker Farm and have been watering at least every other day. Is that too much or too little? Do you have any suggestions for us? (email reference)

A: You have blossom end rot syndrome on the zucchini plants. As for the foliar problem, it could be some kind of fungal problem that has hit the planting. Only a lab test can make a positive determination. I would suggest a broad-spectrum fungicide available over the counter from a local garden center to protect any remaining plants. The end rot problem should resolve itself with future fruit set. However, I’m assuming nothing is impacting the root system.

Q: I have two Canada red cherry trees that have shot hole disease. I have read about a treatment but it doesn't sound like there is much one can do. Will these trees ever recover? If they have it this year, will it recur next year? (email reference)

A: Generally yes, it is futile. You can try to control the disease with excellent sanitation and a full-time fungicide spraying program. However, I have not seen any documentation that can claim success in these efforts. Also, I am always loath to recommend the heavy use of pesticides to control a disease that has a high degree of persistence. Replace the vulnerable tree with a variety or cultivar with resistance.

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 email For answers to general horticultural questions, go to

NDSU Agriculture Communication – Aug. 15, 2012

Source:Ron Smith, (701) 231-7971,
Editor:Rich Mattern, (701) 231-6136,
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