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Hortiscope

Ron Smith answers readers' questions about the world of plants and gardening.

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I have a weeping birch tree that's about 32 years old. It has some rows of holes in the main trunk that I think are caused by a sapsucker. I don't think that they are D-shaped enough for them to be a birch borer problem. The top looks good, with no dying branches, but there are some weak or dying branches on the lower part of the tree. Sapsucker holes are typically lined up in a row. Are birch borer holes lined up in a row? (e-mail reference)

A: Those are sapsucker holes. If they were birch holes, the distinctive backward D-shaped holes would be obvious and the bark would be swollen from larvae feeding activity. Also, in 100 percent of the cases I have known that were birch borer activity, the damage is at the top of the tree on the younger, tenderer branches and thinner bark. Typically, sapsucker holes are lined up, but they also deviate a little. I have a weeping birch in my yard that has the same sapsucker markings.



Q: We chopped down a chokecherry tree and would like to know if the wood can be used in a meat smoker. Someone told us there is something unsafe about using chokecherry wood because it will put a residue in the meat that is poisonous. Is this true or an old wives’ tale? (New Rockford, N.D.)

A: The wood, leaves and pits are poisonous. I am not an expert if chokecherry wood is safe to use in a smoker, but I wouldn't take a chance if it were my decision to make. It probably will not kill anyone, just as the pits that are crushed when making chokecherry jelly have not killed anyone that I know of, but people have different toxic limits. I suggest playing it safe and not using it.



Q: I have never used chemicals in my garden and never want to, but this was my last resort. My garden was almost gone! I used Ortho's Isotox Formula IV on my garden (all plants). The smell was horrible. It still smells bad after three days and some of my plants are wilting or turning brown. Is this product killing my plants? Can I do something before I lose all my perennials? (e-mail reference)

A: If you read and followed label directions, you should not be having this problem. You didn't tell me where you live and under what conditions you made the application, so I can't advise you any further. Isotox should be a selection of last choice to control insects because of the reasons you mentioned, along with the high toxicity it has.



Q: I have two red oak trees that were planted last spring. They only are a few feet tall, but are nicely leafed out. I am concerned about the fact that the leaves are turning a very yellow-green color, especially on one tree. The leaves are not curled. There are some signs of insect feeding on the leaves, but it is very minimal. The leaves look healthy, but I thought oak tree leaves were supposed to be a dark color. I'm hoping there isn't a problem with these trees. Any ideas? (e-mail reference)

A: This could be a reaction to a high pH level, which would tie up available nutrients, especially iron. I would suggest fertilizing with something, such as Miracid or Miracle-Gro, to see if this helps correct the problem. Also, the tree may be planted too deeply or the roots are in a poor-draining soil that remains wet for extended periods. It also could be that root rot has set in.



Q: Was it you who recently spoke on TV about the sticky cottonlike problem with maple trees? Upon checking, my maple and my next-door neighbor's tree have this problem. Both of us are kicking ourselves for not listening closer to your talk about what to do. Help because we want to save our maple trees. (e-mail reference)

A: Yes, it was me. They interviewed me for almost 30 minutes, then used 10 seconds of it on the air, which I think didn't do much justice to this pest. It is known as cottony maple scale. It is an interesting insect that sneaks up on tree owners. This pest becomes suddenly obvious to the most casual observer. There are a couple of options for your consideration. If the trees are large, you would be foolish to attempt spraying with an insecticide. This is something that should be done by a professional applicator. The most effective and least environmentally disruptive treatment is to spray next spring with dormant oil while the trees are still leafless, which is around mid-April. The Bayer company has a super insecticide that can be applied to the root system through a soil drench. The product moves through the entire plant and kills any feeding insects. It is available at local garden centers in our region. Isotox and Orthene also can be used because of their systemic activity. However, I am loath to recommend Isotox because of the horrible smell it produces and its possible toxicity to the plant. Orthene would be the better choice.



Q: My husband and I recently bought a house with a very large grape vine growing in the alley. Is it too late to prune it? When can we expect to have grapes? The previous owners cut it down last year, so they have no idea if it will produce fruit. (e-mail reference)

A: You can tell if it is going to have grapes this year by looking along the vine. You should see little clusters about the size of BB shot. You can prune it now to reduce the vigorous vegetative growth. The best time to prune to bring the vine under control is in the early spring while it is still dormant. You can prune it back to a couple of cordons or a single stem. Groom the plant from there into the vine that you want. The vine should bear fruit and be less foliar productive.



Q: I'm working with new fruit trees that aren’t doing well. The trees are apple, crabapple, plum and cherry. The trees were planted a few years ago and had recycled rubber mulch mats placed around them. The trees also were getting a lot of water through drip irrigation. Based on advice, we pulled up the mats because they were covering the grafts and discontinued the drip irrigation. This spring all the trees leafed out some, so I thought we were on our way to recovery. Now it seems ants have stripped off the leaves on two trees. Is there any hope for these trees? (e-mail reference)

A: Yes, there is hope, but get rid of the ants. This is the first time I have heard of ants stripping the leaves off fruit trees. Go to a garden center and purchase some ant poison to distribute around the base of the trees. The trees should releaf again.



Q: This is my second attempt at planting tomatoes in my yard. I have been able to produce nice plants and fruit, but the skin is so tough that you can hardly eat it. What the heck can I do to avoid this situation? (e-mail reference)

A: Plant a different species of tomatoes. If that doesn't work, I don't know what else to tell you.



Q: My hollyhocks grow great, but there are not a lot of stalks. The stalks are very long and look gangly. Is there a way to prune them early to get more stalks? I'd rather have the stalks fuller and not as spindly. (e-mail reference)

A: Your hollyhocks are probably not getting enough sunlight or perhaps getting too much nitrogen fertilizer.



Q: Do you know what weed is cloverlike with small, yellow flowers that have been taking over lawns lately? What is best to spray on them? (e-mail reference)

A: It could be oxalis because black medic doesn't show its colors until later in the season. It pulls out easily, but that can be too much work. Using Trimec should do the trick.



Q: We are on our second snow mantle dogwood tree in four years. The tree starts out looking beautiful in the spring, but then the leaves curl and droop, producing a very unsightly tree. Is there any hope or should we find another species of tree to plant? The tree is in heavy, clay soil and is on a slope. We thought is was getting too much moisture, so we amended the soil and covered the area around it with plastic before replacing the rock to prevent excess moisture, but this has not helped. Any suggestions will be most appreciated. (Forest Lake, Minn.)

A: You are attempting to grow a tree that is not suited for the environment you are setting it in. Dogwood needs well-drained, high-organic soil, morning sun and no plastic or rock over the roots.



Q: We have a silver maple tree that has all its leaves covered with green pimples. (e-mail reference)

A: Those pimples are caused by the feeding activity of a mite that was active as the leaves were unfolding. This activity resulted in a tissue growth response that is cosmetic and not lethal. These harmless pests will disappear with the falling leaves this autumn. If you want to keep them from appearing next year, have the tree sprayed with dormant oil just as the buds are beginning to swell, but before they open.



Q: I have some Lombardy poplar trees that are dying or dead. Can the trees be used for fire wood? (e-mail reference)

A: Yes, that's about all this tree species is good for.



Q: I have a willow tree with a large hole in the base of the trunk. Should I remove the tree or do you think it can be saved? The tree is about 35 years old and about 50 feet tall. I'm concerned about it possibly falling on my home. (e-mail reference)

A: When willows get that old and have rot taking place at the base of the trunk, you are better off having them removed before they collapse on your home or someone in the area. Be sure the tree service is competent, certified, bonded and most importantly, insured.



Q: In your column there was a question from a reader about where to find wildflower mixes and native grass seed. You mentioned two good companies, but I thought you might like to hear of another located in Brookings, S.D. Millborn Seeds has been in the native grass and wildflower market for more than 19 years. We access seed from across the U.S., but primarily in the upper Midwest, which makes it very suitable for your readers. If you would like more information, go to www.millbornseeds.com. (e-mail reference)

A: Thanks for the information! I am always in need of some new sources of information and suppliers.



Q: I have an oak that is dropping little, beige/yellow balls that look like tiny seeds. Sometimes (I swear) the little balls are jumping. We are fighting gypsy moths with this tree (we lost three ash trees last year to ash bore) and I don't want to take a chance on losing any more trees. I have five other oak trees in front of the house, but they don’t have (or I can't see) these tiny seeds. Please tell if I need to do something. Thanks for your time and information. I appreciate it. (e-mail reference)

A: What you are probably witnessing are acorns infested with acorn weevil larvae. Insecticides may or may not be useful at this stage. I suggest getting an International Society of Arboriculture arborist out to examine the trees to see what action can be taken to bring this and the other pests under control.

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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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