June 8, 2006

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I am writing this e-mail in hopes you can help me save my May Day tree. I live in Alaska. The tree is in the backyard and gets morning sun. It is a fairly young tree, but it is reaching the top window of my two-story house. Two years ago, I noticed that the bark of the tree was split from the grass line to about halfway up. I tried putting tree wrap around it to keep the bark in place. After a number of months, I took the wrap off and noticed that the bark had curled, leaving more than half of the inner tree exposed. That exposed part had slugs and spiders on it that I removed. The exposed spot is now black with some white areas. It managed to survive another harsh winter and has buds on it. I really like this tree and I don’t want to lose it. Is there something I can do for it or am I eventually going to end up losing it? (e-mail reference)

A: You did the right thing by removing the wrap and keeping the exposed area clean. The tree will work on healing itself during the growing season. Don't paint it or add any unneeded fertilizer. It should be OK because May Day trees are pretty tough. We have them in North Dakota as well.

Q: I’m checking to see if you have any information on what is best to add to the soil to help loosen it for a flower bed. (e-mail reference)

A: You can try peat moss. It can be bought in bales at your local garden center.

Q: I just noticed that the new buds on my Colorado blue spruce trees have black around them. I planted them two weeks ago. There was a hard frost two days ago, but I didn't notice the black until yesterday. Are the trees suffering from frostbite? I also am wondering if I am watering them too much. I watered the trees a lot the day I planted them, the next day and twice since then. Is this it for my spruce trees? (e-mail reference)

A: Your spruce trees have been damaged by frost, which likely killed off new growth. They should be fine and bounce back. Water your spruce trees about once per week.

Q: I have an individual who is getting rid of some trees. Is there a way to prevent the trees from growing back? I was told by the homeowner that he has to go through this process every two or three years. I also have an individual with honeycrisp apple trees who is having problems with rabbits. On one tree, the rabbits ate a quarter of the bark around the tree. On the other tree, there only is a sliver of bark still connecting the top and bottom of the tree. It appears there is enough bark for the tree to survive, but I’m not sure. The tree is budding. Is that a good sign or is it still too early to tell? Is there anything we can do to help the trees? (Lisbon, N.D.)

A: Tell the individual to wait until the trees have fully leafed. This process burns up a substantial level of the carbohydrates stored from last fall, resulting in a minimum of regrowth. It is too soon to tell, but I'd be surprised if the tree survived. Very little can be done unless the individual wants to attempt bridge grafting, which requires experience, skill and luck.

Q: I have read your Web site devoted to peonies. This is my first year in an old house that has several clusters of peonies. I am wondering how often I need to divide the clusters. They are blooming beautifully, but I don't know how old they are. What should I use as a guide to determine when I should divide them and what time of year is best to do this? (e-mail reference)

A: A good rule of thumb to follow in dividing plants is to do so when they begin losing vigor or the ability to bloom. Another rule of thumb is to divide spring blooming plants in the fall and fall blooming plants in the spring. Of course, rules are just that and have been broken many times with success. Most peonies can go five or more years before dividing is needed. If they are doing OK, I would suggest leaving them alone no matter how long they have been in one location without being divided.

Q: I am looking for something that will drive away robins without harming them. I have looked on the Web and seen some devices, but I was hoping there was some sort of home remedy that would stop them from perching. The robins have found a particularly favorite spot and I was hoping that we could keep them away. Thanks! (e-mail reference)

A: You make this a very tough question to answer if you don't want any devices. I only can make the same suggestion that I would for keeping woodpeckers out of trees. Spread some Tanglefoot on the branches where they typically perch. This is very sticky stuff that birds abhor getting on their feet. It doesn't hurt the birds, but the Tanglefoot does irritate them to the point where they will move to another tree. This is not a home remedy, but close to it.

Q: I purchased a "greenhouse" last year. Can plants, such as tomatoes, peppers, beans and cucumbers, be grown from start to finish (seed to bearing fruit) in my green house? I've battled a little with rabbits and other wildlife where we live and was hoping I could keep some things in the greenhouse all summer. My kids said that my greenhouse is not green, so I can't call it that. So now we call it the garden house. It's made of hard plastic. The roof has a couple of skylights and one side (facing south) has a big, curved window. That's where most of the shelves are for the plants. Also, what is the best product to use to kill grass and weeds in my flower beds and raspberries without hurting the plants that I want to keep? (e-mail reference)

A: You can grow those plants from seed to fruiting in your "garden house." Ask your kids if you can call it a greenhouse once you gets plants going in it. To control unwanted grass around plants, look for a product that contains sethoxydim. The product is called Grass Killer and is under the Hi-Yield brand name.

Q: I have a question from one of my neighbors. She has done some landscaping at her farm because of a tornado that went through just west of her house. She has planted silver maple trees, but they are suckering more trees. She has tried putting down landscape fabric, but the suckers push through the fabric. Is there a physical or a chemical plan to take care of the suckering problem? (e-mail reference)

A: Believe it or not, there is a product called Sucker-Stopper RTU. If it is not available locally, she should be able to find it on the Web. Cut the suckers back and then spray the surface of the cut. It usually works for the entire season. While some suckering is to be expected, usually heavy suckering is a symptom of the tree being planted too deeply or under some kind of stress. You might check for these two possibilities.

Q: We have established peonies. This spring nearly all of the plants have red leaves instead of the normal green. Some of the plants have their normal green leaves. The leaves are a bright, light, red color. Could this be a fertilizer problem? (e-mail reference)

A: I doubt this is a nutrient problem. More likely it could be related to the cultivar of peony and the juvenility of the foliage. If the peonies don't green normally in a couple of weeks and it doesn't look like they are going to produce any flowers, then something else is causing this problem because I don't know of any mature red-leaf peonies.

Q: We have very sparse foliage on our silver maple tree. The tree is about 40 years old and 20 feet tall. The crown of the tree is almost bare. Our neighbor had a silver maple a few years back, but had it removed. We heard that if the removed tree was male-female, it would affect our tree. Is this true? Right now the tree is full of seed pods. A few years ago we checked with a nursery and were advised to use tree spikes as a fertilizer, but that did nothing for the tree. (e-mail reference)

A: The tree is doomed. When it sends out that much seed stock, it is an indication that the tree is in final (or close to it) decline. I would suggest getting it removed as soon as possible so it will not be an eyesore or a safety threat. Tree spikes are about the most useless treatment you can give to any tree. Silver maples are monoecious. That means they have both sexes of flowers on the same plant, so the removal of your neighbor's tree had no effect on yours.

Q: I have a Madagascar dragon palm that is 8 feet tall. I am running out of places to put it because it is so tall. Can I cut the top back? Will it branch out again? Any suggestions would be greatly appreciated. Thanks for your help. (e-mail reference)

A: You can and you also can do an air-layer on the part of the palm you cut off and then plant it. Go to www.ext.nodak.edu/extpubs/plantsci/landscap/h1257.pdf and download a copy of my publication, "Home Propagation Techniques.”

Q: I have two rose bushes, a Morden centennial and a William Baffin. They are hardy and winter well. During the growing season, the roses are plagued by insects and fungus. They bloom in the spring, but then disease takes over. I have used Bayer Advanced Garden Rose, Flower Insect Killer and Garden Safe Fungicide. The leaves are just beginning to come out. Is there anything I can do with the pests and fungus to stay ahead of the game? Maybe I didn't start early enough last year. I have used Miracle-Gro rose food about every two weeks as directed. The fungus produces black spots on the leaves that then turn yellow and drop off. The county agent said the insects were alfalfa bugs. (Jamestown, N.D.)

A: It should do the job if you stay ahead of the arrival of insects or pests and apply protective sprays every 10 to 14 days.

Q: I have a very large weeping willow in my backyard that is very near my house, but I love the tree. We are adding on to the house, so I'm wondering what chance it has of living if some roots are cut during construction. How can we help the tree during construction? (Moorhead, Minn.)

A: Discuss the tree's welfare with the contractor so he or she is aware of your concern. You or the contractor needs to erect a protective fence around the tree as far away from the trunk as possible, but still allowing the construction work to be carried on. When the roots have to be removed, make the final cut with a saw or loppers. A saw or loppers will give you a straight, clean wound and not a jagged cut. Do not allow any waste soil or construction debris to accumulate under the tree's canopy. Do no allow any heavy equipment to run under the tree's canopy without putting down sheets of plywood or steel plates to keep the soil from being compacted. If any branches are going to be in the way of the construction activity, have them professionally pruned before any construction equipment gets a chance to damage them.

Q: We have some apple trees that are 40 or more years old. I’m sorry, but I don't remember the brand name of the apples. The apples used to be white all the way through, but the past few years the inside of the apples are red. They were good pie apples, but with the red color they no longer are apples to eat. Any suggestions? (Valley City, N.D.)

A: Sorry, I don't have any answers. I have not heard of this happening, so I don't know the cause. If it impacts the taste, certainly don't eat the apples.

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Source: Ron Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu

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