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

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I purchased three white flower dogwoods. Two of the three died, but I took them back and had them replaced because there was a guarantee on them. The problem is that they grow for two to three months, but then the tree starts dropping leaves and the branches turn very brittle and die. The only possible cause I can think of is that I had two Bradford pear trees that split during a wind storm, so I removed them and had the stump ground down. I saw that there was a disease that entered the root and killed the trees from the inside by decomposing the root base. I did plant the trees next to the stumps because my front yard is very small. Is there anything I can put in the ground that will kill the fungus or should I just give up and find another species of trees to plant? Your help would be wonderful. (e-mail reference)

A: If you planted them in the same location where the stump was ground down and all the sawdust not removed, that could be your problem. Unweathered sawdust will generate heat as it breaks down. I'd suggest removing all the sawdust before replanting with anything. Raw sawdust will heat up as it begins breaking down and will tie up the available nitrogen that feeds the active microbes working on the sawdust.

Q: I inherited a rather large croton that is in a very big pot. The plant has grown into three trunks but only has leaves on the top of each limb. Is there anything I can do to encourage growth on the lower limbs? Would pruning the plant help? Thanks for any help. (e-mail reference)

A: Sometimes plants show strong apical dominance that keeps the lower buds from breaking. Pruning the plant back definitely would cause growth from the lower buds and give you a bushier plant.

Q: I have pear, Japanese plum, fig and two plum trees on a small tract of land. I am having problems with worms in my plums. Is there anything productive that I could put in the soil around the roots before the spraying period? Also, please give me a good grape or scuppernong vine for this area that would require minimal maintenance. (Montgomery, Ala.)

A: You need to check with the Extension Service in Alabama to see if a pest control specialist can recommend anything that you can apply systemically that will minimize the infestation in your plums. In some cases, Imidacloprid has been used as a postharvest cleanup on fruit. Go to to make contact with an agent who can hook you up with a pesticide specialist. As you obviously know, scuppernong is the original American wine grape. As far as finding a minimal-maintenance vine, I don't think there is any such thing. For help, go to or One or both of these sites should provide some good information for you. You also could contact the small-fruit specialist at the University of Alabama.

Q: During the past month, my wife talked with you about fruit on flowering almonds. For the first time since planting 10 or more years ago, we got a couple of large handfuls of almonds. They aren't very large, are hard to open and bitter. No one we have talked with knew that the ornamental plants could produce fruit. If you would like some for any reason, please let me know and I will send some to you. Your shows on North Dakota Public Radio are interesting and we look forward to them. (Minot, N.D.)

A: The flowering almond rarely sets fruit, and it is just as well that it doesn’t. The nut contains a bitter compound that is a precursor to cyanide. You probably (fortunately) found even one nut difficult to ingest because of the extreme bitterness. Had you been successful in eating just one, the result could have been a tummy ache. So, be warned, my fan of NPR's "Hear it Now" program. Don't eat any more of the almonds. Just look at them with a mild pride that your shrub is one of a few to ever have produced fruit.

Q: We have two honeycrisp apple trees that have produced fruit since their second year of growth. However, I think they are dying or already dead. The trees did leaf out this spring and produced a few apples. I thought the low number of apples might be due to the late frost this spring. However, both trees had branches turn brown after leafing out. The number of brown-leafed branches has grown. They are planted on either side of a Haralson apple tree that is not having problems. Any ideas what might be going on? I was wondering if you thought it might be fire blight. The problem doesn’t seem to act like fire blight because I don’t see crooked ends on the branches. I wonder if we should call it quits and remove the trees. (e-mail reference)

A: It could be low-temperature damage, root rot or a progressive canker that is killing these trees. Based on what you've told me, I'd suggest removing the trees because I doubt they will get any better. While the Haralson is a very hardy and disease-resistant apple species, I wouldn't tempt fate by keeping the two honeycrisp trees around much longer. Consider replacing them with either state fair or zester apple trees. We've had good luck with these two in our region.

Q: I have a question about transplanting wild cedar bushes. I have several of them growing wild on my land here in Texas. I would like to move some of them to make a windbreak for my house. Can they be moved? What would be the best time to move them? I have sandy land that drains well. Also, do I need to water them a lot if they can be moved? Would I be better off buying some from a nursery? (e-mail reference)

A: Young trees from a nursery with roots that are 100 percent intact always will trump digging and moving a tree. It is a judgment call on your part. I would assume that the ones you are considering moving are larger than those from the nursery. I vote for the nursery purchase because I think you'll be happier in the end.

Q: We have 12-year-old lilac bush. For the first time, we noticed the bark is splitting in a few areas. Now there are holes in the bark with yellow goo oozing out. We sprayed the split areas and the holes with some sort of bark tar. We also noticed and killed a very large bee hanging around the bark. The bee looked like a fat, long yellow jacket. Is there anything we can do to save this tree? Now a few of the top leaves are turning black. (e-mail reference)

A: What you killed was not a bee. It was the female adult stage of a lilac/ash borer. She already has laid eggs that have hatched and are feeding on your lilac just under the bark. This causes the yellow goo you described. If possible, cut the lilac back beyond the visible damage and dispose of the cut material. Get some systemic insecticide and apply it according to label directions next spring before new growth begins. The material will be taken up through the vascular system of the plant and kill any future feeding insects.

Q: I have two calla lily plants I want to bring in for the winter, but I am not sure of the proper procedure. Do I need to dig out the bulbs and dry them out? Can I bring in the plants and withhold water for a few months to let them go dormant and start watering them again in the spring? I live in western New York. (e-mail reference)

A: Assuming you have them planted in western New York soil, I would suggest that you dig them out, clean the bulbs and then allow them to dry. Repot the bulbs in fresh potting soil for next spring's rejuvenation.

Q: I have common thyme, curly parsley, English lavender, Rosemary and curry plant that I would like to transplant to a garden bed before winter. Are they hardy for Zone 4a and 4b? Would protecting the plants help them overwinter? (Canada)

A: Herbs in a container in Canada through the winter would suffer winter kill. I suggest plunging them, pot and all, into the soil and mulching them after the first freeze-up. They should make it if the timing is right and winter doesn't intend to set record lows this year.

Q: I have several different evergreens that were planted by the previous owner 30 to 40 years ago. In the past year or so, the trees started losing needles. They are losing so much volume that I can see through the trees. Is there something lacking in the soil? (New Jersey)

A: You need to make a local contact. Go to to find a New Jersey Extension agent who can assist you. In all likelihood, an onsite visit will be needed and samples sent to the Rutgers plant disease clinic for analysis. I cannot give you valid advice without more complete information. That is something only local personnel can do. Sorry!

Q: I read an article that you wrote about covering strawberry plants for the winter. You mentioned that covering them with a Remy winter blanket was a good way to protect them instead of covering them with straw that could have a lot of weeds in it. I have been trying to find more information about this Remy winter blanket, but I am unable to find anything. Where can this blanket be purchased and where can I find more information about it? (e-mail reference)

A: This product is getting hard to locate, but you can find a list of other products at Get your order in soon because winter is just around the corner!

Q: I own a ridge at approximately 2,000 feet elevation in the northern Catskills of New York. A stand of 60 Norway spruce trees protect me from the north winds. They are beautiful trees but were planted too close. Several of the trees on the north side have turned brown and died during the past several years. I now see that some trees on the south side are losing their needles from the center out after first turning brown. There has been a dramatic progression of this during the past few weeks and more trees are infected. The only noticeable symptom is a grey fungus covering the branches as they drop their needles. However, I was told this is a secondary opportunistic disease. I can't get the local Cornell Extension people interested in coming out to look at the trees even after bringing them some branches. An arborist from 50 miles away is scheduled to look at them. However, I would like to have some information so I can evaluate his or her recommendations. From reading other letters, it sounds like it might be spider mites, but I can't find any sign of them. It will break my heart to see these trees die. (e-mail reference)

A: From my peripheral watching of the weather and having family in your region of the country, I don't think you have a spider mite problem because of all the rain your area has received this summer. Keep in mind that some of the needle death is normal and takes place at this time of year. However, some of it could be caused by disease. What you are describing sounds like cytospora canker, which is a somewhat common ailment in older spruce trees. The disease usually weakens but seldom kills the trees it attacks. The disease starts on the lowest branches of the tree and progresses upward through a period of several years. At first, the needles have a purplish hue but eventually turn brown and drop off. This leaves dry, brittle twigs and branches. On severely infected trees, the fungus will enter the trunk through wounds (usually where the branch meets the trunk of the tree) to kill the cambium layer. This dead tissue is called a canker. A conspicuous white resin or “pitch” covers the cankered portion of the branch or trunk. This resin sometimes flows several feet down the trunk of the tree. This is an important means of diagnosing cytospora canker. However, resin flow also can be associated with other tree injuries and is not exclusively symptomatic of cytospora canker. Within the cankered area, black, pinhead-sized fruiting structures (pycnidia) of the fungus can be seen with a microscope or hand lens and are a positive sign of the disease. Canker development is most severe in trees under stress from drought, insect damage, crowding, nutrient imbalance or mechanical damage to branches, trunks or roots. Symptom development becomes more common one or two years after a severe summer drought. Because cytospora canker is a stress-induced disease, trees should be planted in sites that are favorable to their growth. Minimize the stress on established trees by taking care not to injure the root system or compacting the surrounding soil. Use a 3- to 4-inch layer of organic mulch to retain moisture and reduce rapid soil temperature fluctuations. Water well in dry periods and provide adequate moisture in late fall before the ground freezes. Improving soil quality will reduce stress. Infected branches should be removed to improve the appearance of a tree and reduce the chances of spreading the disease. Avoid pruning or working around trees when the foliage, twigs and branches are wet because water disperses the fungal spores. Clean your tools thoroughly and disinfect them with rubbing alcohol, a 10 percent bleach solution or a comparable disinfectant after each cut when pruning out diseased wood. Unfortunately, no chemicals have been found to be effective in controlling this disease. Your arborist likely will recommend thinning the trees somewhat and attempting to overcome stress on the trees with fertilization and selective pruning of dying or diseased branches.

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

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