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Hortiscope

Ron Smith answers questions about plants, trees and gardens.

By Ron Smith, Horticulturist

NDSU Extension Service

Q: Two years ago, we planted an autumn blaze maple tree. The first year, it did well. At the end of the summer, a rabbit stripped the bark halfway around the trunk and about 8 inches high. Since then, it has not been growing. Is there anything we can do to save this tree? (e-mail reference)

A: I'm afraid not. The rabbit has girdled the tree while it was young, which resulted in it dying. Sorry. Next time, wrap any tree you replant for at least three to five years to prevent rodent damage.

Q: I have an older silk lilac tree that I would like to move. Is it possible to move a tree this established? If so, what is the best way to ensure survival? I cannot get a truck into my yard, so it will have to be done by hand. (e-mail reference)

A: You would need to get a professional landscaper to move a tree this size and age. The best time is early in the spring before leafing out takes place. There is no way to ensure survival; just hope that it does! It all depends on the extent of the move, range of the root system and how different the new site is from the current location. Like humans, as they get older, plants don't like changes being imposed on them!

Q: I have eight Christmas cactus varieties that periodically drop green legs. Their ages range from three to 20. This started happening in the last 12 months. They all look healthy. What could be the cause? (e-mail reference)

A: If I could nail the cause from the information you provided, I'd be in the genius class, which I'm not. What I can give you are some probabilities and leave it up to you to determine which of them, if any, are the cause of the occasional leaf drop. Something has changed in their immediate environment, such as cold or hot air drafts, lower light, change in watering regime, normal aging response, need for a rest period (where water and temperature are decreased) or simply a move to a different location. The other possibility is an infestation of either scale or leaf miner insects. Leaf miners leave symptoms of little white irregular tunneling lines in the foliage. Depending on the species, scale insects can disguise themselves so that they are barely noticed as little bumps along the stem or leaves that can be scraped off with your thumbnail. Both insect pests can be controlled with the use of a systemic insecticide. Not knowing what care you provide for these plants, it is a good idea to summer them outdoors along the north side of your house or under the canopy of a tree. This will toughen them up to tolerate the normally low light and low humidity conditions of most homes during the winter months.

Q: I am a novice to gardening, but I can't help but wonder what it might be like to create new types of daffodils and roses. Can daffodils and roses be cross-pollinated? (e-mail reference)

A: The answer is no because Mother Nature won't let it happen. They have to be in the same family, which these two are not. Working within these two species, many new and beautiful cultivars (varieties) have grown through the years. Feel free to try it on your own. Who knows? Someday you may be famous with a new introduction!

Q: I have two old Concord grape vines, but my arbor fell over. How do I get the large vines to start growing on the new arbor? (e-mail reference)

A: Prune them early this spring or when you can get to them. After that, just stand back! With a little coaxing and guidance on your part, your old vines will be able to cover that new arbor in no time at all!

Q: I have 13 arborvitaes that are about 9 feet tall. I want to trim them back to about 2 feet. What would be the best way to do this? (e-mail reference)

A: With a pair of long-handled loppers, reach in and cut the main stalks back just above a branch coming out of one of the trunks. This is a drastic reduction, so I'm not sure you or the arborvitaes will be happy with the results.

Q: I am a North Dakota native now living in south-central Pennsylvania. I have a very large yard. I would like to plant trees to provide some colorful fall foliage. I was thinking about using silver and red maples, along with some white birch and quaking aspen. I know aspens sucker, but how big of a problem is suckering with maples and birch? Do you recommend lining my driveway with maples or would their roots disrupt the road? (e-mail reference)

A: Very little to none as far as suckering from the birch and maples. If you line your drive with maples, I would suggest using sugar or red maples. Silver maples tend to develop large surface roots. Plant them at least 15 to 20 feet from the edge of the road to minimize their impact on the road surface. Assuming you are talking about a dirt road driveway, that soil would be compacted so hard that the roots probably would not grow.

Q: I have about 25 arborvitaes that were planted next to a fence around our backyard. That was about 18 years ago. They never have been trimmed since then. I'm going to try trimming, but if we decide to get rid of some, how difficult is digging them out? Do they have big roots? (e-mail reference)

A: I can assure you that you have your work cut out for you! After 18 years of growing in one location, they will have an extensive and thick root system. I don't know your age or what kind of shape you are in, but I would encourage you to get some local high school athletes to come over for a pizza and digging party to save your back!

Q: A few years ago, there were some farms you could buy shares in. The garden crops were selected and grown by the farmers. Every week, they would come to town to deliver the ripe crops to the people who bought the shares. Do you know if there still are farms like this? If so, how can I contact them? I am interested in doing this, but I am not sure how to locate someone who does this. (e-mail reference)

A: What you are referring to is known as CSA or Community Supported Agriculture. This is a moving target because farmers are getting in and out of it all the time. It has not been a resounding success in North Dakota. There were two listed in the database in 2004 and none in 2008. However, data like this only is as good as the people gathering it or letting their business operations be known to the North Dakota Department of Agriculture. I would suggest that you inquire with some local folks, such as the Chamber of Commerce, restaurants that specialize in locally grown food or others that cater to the high end of the market. Other than this, just keep your ear to the tracks to pick up anything that may be coming on the scene this spring. It usually makes the rounds with vegetarians or vegans in the community like a prairie fire. If any should be brought to my attention, I'll get back in touch with you.

Q: I have two ficus trees in very large pots. I live in North Carolina where the temperatures can get below freezing. Is it possible to plant these two trees in my yard? (e-mail reference)

A: Not if you want to keep them for more than a year. Ficus trees are tropical plants, so they are intolerant of any freezing weather. Sorry!

Q: I have had a cactus for about 15 years. It is tall and in great health. However, I need to repot it because I accidently punched a hole in the plastic pot. Are there any tricks or tips on moving a large cactus? If by chance this cactus gets too large for my apartment or home, do you know of anywhere that would take a very large cactus? I have had it since it was about the size of my thumb. (Fargo)

A: The only trick I know of is to be careful! Wrap the cactus in layers of newspaper to prevent skin puncture and roll it like a barrel. I'm no expert, but that is what I've done in the past. As to finding a home for it, I'm not at liberty to make any suggestions either for NDSU or anyone else in the community. If I should get a clamoring for your plant, I'll certainly let you know.

Q: Can I spray neem oil on my marigolds? They keep getting a speck-type disease. Eventually, all that is left of the plant is the flower. (e-mail reference)

A: You can spray neem oil on your marigolds unless the label says otherwise. It is a unique product with fungicidal, insecticidal and miticidial activity. With all of that, it may not have the ability to stop whatever is happening to your marigolds, but give it a try to see if it does work.

Q: We live in Putnam County, N.Y. (northeast). We are going to plant two white dogwood trees. We just purchased them today and are hoping for some help with the planting process. What do they need as a base? How far down and apart should we plant them? We hope to plant them in a few weeks because we still could have a frost. (e-mail reference)

A: I would advise getting them into the ground as soon as the frost is out of the soil. Plant them so that the crown of the tree (point where the stem or trunk stops being the trunk and becomes the root system) is even with the surrounding soil. Dig the hole two to three times wider than deep. Modify the backfill soil with sphagnum peat moss and then set the container in the hole. With a sharp knife or pruning shear, peel the sides and bottom of the pot off the root ball. Back fill with the modified soil, water in well to settle the plant and bring the soil level up to the crown. Mulch around the tree with bark or sphagnum peat moss. Leave about an inch free of mulch around the trunk. Monitor the tree for water needs as the season begins. A fear of frost damage is irrational because these are frost-hardy plants. They would fare better if they already were in the ground.

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 ronald.smith@ndsu.edu.


NDSU Agriculture Communication

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