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Ron Smith answers questions about the world of plants, trees and gardens.

By Ron Smith, Horticulturist

NDSU Extension Service

Q: My birch tree may have birch borers. I remember injection treating the tree for this a number of years ago. When should the tree be treated? Can I have it done this fall? (e-mail reference)

A: Fall is a good time to do this because it will be active in the tree next spring. Instead of injection, it can be applied through a drenching around the crown (trunk base). The product is called Bayer Advanced Tree and Shrub Insect Control. Be sure to follow the directions to get effective control.

Q: We planted a Deborah maple last year. While we were gone one day, deer chewed off the bark on two sides of it. The deer broke the tree guard off and proceeded to chew away. I am in a near panic. Can this tree be saved? What should I do for it? Can I put something on the chewed- off area? I did tape up a tree once that was hit by a lawn mower and the tree survived. Would this work for my maple? If you or anyone you know likes to hunt deer, feel free to come out and take all you want. They are ruining everything around here. (Tappen, N.D.)

A: Sounds like it is time for a venison picnic! There is a chance a tree can be saved if there is any bark running continuously from the crown to the branches, which it sounds like it does in your case. I assume you have tried all of the deer repellents, but they didn’t work. If not, try them. Sometimes repellents work, but it depends on the local deer population and whatever else there is to feed upon.

Q: I don’t know what to do with my apple tree. It has some sort of disease on the leaves and the apples. It has a ton of apples on it, but they are all spotted. How can I help the tree or should I cut it down? (e-mail reference)

A: Get someone who knows what he or she is doing to inspect the tree for removal or start a rejuvenation program. From what you said, it probably can be saved and become productive again, but that is something that an on-site visitation could determine.

Q: I am being invaded at night by creatures digging shallow holes in my lawn. It looks like they are digging for grubs. Any idea what is doing it and is there a remedy? (e-mail reference)

A: This could be skunks or moles. If it is random digging and not tunnels, most likely it is skunk activity. As for the remedy, you would need to take that up with the local wildlife authorities.

Q: I saved some seeds from my Stella D’Oro lilies this year. If I plant them, will they come up and bloom? (e-mail reference)

A: Give it a try. You never want to pass up a possible opportunity to be successful at something you’ve never tried before! You’ve got nothing to lose.

Q: I planted hackberry trees this spring. There are very few leaves at the top and they are small. There are bigger leaves at the bottom of the trees. What is going on with my trees? (Faith, S.D.)

A: The trees are just taking their time getting established. Hackberry tends to be that way, so I'm betting that next year they will be more normal.

Q: I noticed you’ve had several posts about hackberry trees. We have a very large one next to the house. Last year, we started having a problem with bark dropping all around the tree. To the best of my knowledge, it seems to be the younger limbs that have softer bark that are affected. I believe small woodpeckers may be stripping the bark. It has me concerned they may be after some type of bug. This year, the problem has continued. About half of the new growth is dead. Otherwise, the tree looks very healthy and has many leaves. We have had a fair share of dead limbs fall on the house, so I thought this may just be its life process, but there seems to be more dead limbs now. (e-mail reference)

A: It could be woodpeckers or squirrels. Whatever it is should not be ignored. Contact an International Society of Arboriculture certified arborist to inspect the tree because it would be impossible to replace should it be lost. Be sure the individual is more than a tree trimmer. You want someone who has plant diagnostic ability. Check the person’s credentials and ask for references because someone doing the wrong thing to this tree could accelerate its decline.

Q: I discovered some new crepe myrtle trees in my yard. Because of their location, these trees had to have been started by seed. When does a crepe myrtle seed? I’d like to try growing some using the seed method. I know that I can do cuttings, but starting with seeds could be a good project for someone who will be retiring very soon. We live near a highway and bought a few trees with the hope of getting a sound barrier when the trees get large enough. (e-mail reference)

A: If you leave the flower stalks on after they have finished flowering, that is when they seed. Different types flower at different times. It also is based on location. The best and easiest trick is to allow the seed heads to remain until early January. At that time, collect and sow them. You should get good results. This timing gives the seeds the cold treatment they need. By then, you should have experienced some 30 to 45 days of cold weather.

Q: There are many wild asparagus plants growing and flourishing in the ditches around us. I would like to transplant some of them, so I need to know the best way to dig them up and move them. Where should they be planted? (e-mail reference)

A: Dig them after a killing frost and plant them at the same depth. Give the plants full sun and as close to the same soil type they were growing in as possible. Water in completely upon planting and wait for next spring to bring forth the produce!

Q: I have a black walnut tree that has dropped many nuts. Now I am seeing what look like walnut trees growing around the perimeter of my yard. Is it possible that these are walnut trees? A couple have grown very tall. (e-mail reference)

A: That is a perfectly logical assumption to make. Most likely squirrels planted the nuts. If it is your intention to replant them somewhere, select the smallest ones to move because they develop an extensive taproot quickly. That makes moving the larger trees more of a challenge.

Q: Do you know of a way to get rid of the green moss growing around the edges of my raised flowerbeds? It looks like fur growing, so that is why I think it is moss. It is bright green. Do I have to dig it out of the ground? (Fargo, N.D.)

A: The best way to get rid of moss is to dig it out. Copper sulfate is used on walking surfaces to control algae and light moss growth. However, it has toxic effects on anything else it touches. The moss will not hurt anything other than your sense of aesthetics. If you can bring yourself to live and let live, it will be easier on you!

Q: We had a poplar tree in our backyard that grew so tall that we were concerned about the neighbor's house being damaged if the tree fell during high winds. We had the tree removed last October and the stump ground out. This summer, sprouts grew all over the backyard. I purchased some brush kill, but other sprouts grow back in a few days just inches away from the ones I killed. Out of curiosity, I dug around some of the sprouts that are near the original trunk. To my amazement, I found a hearty root system that was full of moisture. When I have free time, I dig out some of the roots. The roots range in diameter from very small to 10 inches. Is digging out the roots my only solution to prevent regrowth? Will the roots die on their own? (e-mail reference)

A: If you had the patience to continue spraying the brush killer or any good systemic herbicide, you eventually would have won the battle. In addition to being the anchoring system for the tree, the roots are the warehouse for food. In most species, when the top of the tree is removed, that energy is transformed into adventitious growth of new stem tissue that is capable, through the process of photosynthesis, of prolonging the life of that root system for many years or indefinitely. You have been giving yourself a good workout with all that digging, but now it can end by applying Trimec or some other systemic herbicide when new shoots appear. You will win, I promise!

Q: We have a willow tree that is beautiful and huge. We built a swimming pool about 10 feet from the trunk and added a cement wall between the pool and tree. I have started noticing the roots of the tree in the grass area around the pool. My concern is that the roots will get to the pool decking and cause damage. My question is how to control the growth of the tree. I would like to keep the tree if possible. If I trim the branches, would it control the root growth? Would building an underground cement barrier stop the roots from expanding? (e-mail reference)

A: Controlling willow roots is like trying to control an unruly teenager. I would suggest getting a certified arborist to analyze the situation and make a professional recommendation. Root barriers can be installed to kill the root tip without hurting the tree.

Q: I purchased a small canna plant for my outdoor flower garden. It grew very large and produced at least six large red flowers. There are some new shoots around it, so I am wondering how to preserve it for next year. Can the new shoots be planted indoors for the winter? Should the main plant be cut down and mulched? I am from North Dakota, where the winters are very cold. (e-mail reference)

A: The best approach is to dig the plant up after a good frost that will kill the foliage. Then cut the foliage from the crown. Shake as much of the soil off as you can and store it in a cool, dry basement. Dust it with sulfur or a Bordeaux mixture to help prevent diseases from getting established. Check it frequently during the winter storage months to be sure no rot is getting started. Remove any that is apparent with a sharp knife or pruners. In March, get some sterile or pasteurized potting soil and a freely draining container and repot the plant. You can divide off some of the offshoot bulbs if you wish and pot them as well. Place them where the plants will get excellent light (naturally or artificially). When danger of frost is past, move them outdoors to a sunny location.

NDSU Agriculture Communication

Source:Ron Smith, (701) 231-8161,
Editor:Rich Mattern, (701) 231-6136,
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