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

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I found your name on the Web, so I figured would take a shot at having my question answered. I am looking at planting 10 to 15 emerald green trees to act as a screen. I really like the tree, but my concern is about deer. I have not found anything definitive on the Web, but I did read one column that says deer will devour the base of the tree. I have a ton of deer around my place, so this would be my only reason for not planting emerald green trees. Can you offer any insight? If this tree will not work, can you offer other suggestions? I am looking for privacy and something that does not grow too tall. (e-mail reference)

A: If you are concerned about deer damage, then don't plant this or any other tree because deer don’t discriminate about what they devour. You would be better off considering a privacy fence rather than attempting to get anything alive established. I've received far too many e-mails from frustrated clients who have tried every trick in the book to get deer to quit eating on trees. It has cost these people a lot of money with very little success.

Q: My neighbor has two old apple trees. He pruned one back severely last year and it blossomed wonderfully. However, I’ve noticed a whole branch with dead leaves and a couple of other spots where leaves were dying on smaller branches. There's some fruit set on the tree, but not as much as one would think with the way it blossomed. Could this be the work of flat-headed apple tree borers? Do you have any other ideas? He said he planned to prune off the dead areas, but he's elderly and it's probably not a priority for him to solve the problem. I'm just learning about apple trees, so I want to find out what the problem is. (e-mail reference)

A: It does sound like borer activity, although cankers circling the branch could cause the same results. Sanitation is the only answer I can offer. Remove and burn the affected tree parts and pick up all of the dropped fruit. Also, spray the tree with lime-sulfur in early spring, but before leafing out takes place.

Q: I have a burr oak tree that appeared to have rot on one side close to the ground. The spot is about the right height for the dog and cats to bless it daily. After closer inspection, the tree appears to be oozing from holes in it. Also, hardly visible are tiny worms. What are they and how can I save the tree? No damage is apparent on any other part of the tree. Please help because this is one of our prized oaks. (e-mail reference)

A: Get in touch with an International Society of Arboriculture certified arborist to inspect the tree to see what needs to be done to save it. These might be borers or something else that could cause further damage to the tree. The problem also could be an insect that is simply feeding on the decaying wood, but you need to find out and get corrective action started.

Q: I really enjoy your column. Keep up the good work! I was wondering how to get rid of field bind weed in my garden. I have painted on Roundup, but only sets it back a bit. Anything else I could use? Also, we had a bad hail storm, so a lot of our trees got stripped. Some have very few leaves left. What is going to happen to the trees? Will they grow new leaves? Will they die? Thanks for your help. (e-mail reference)

A: Try the same technique with Trimec because the weed may have resistance to Roundup. If you can do it later in the year, chances are you will have a more successful kill. The roots on this thing go down forever! If the trees were sound, they will releaf this summer and probably recover. Be patient because there is not much else you can do.

Q: I have a large household spider plant. I just noticed two different patches of light green toadstools in it. The plant (which has been extremely healthy and green) is losing color and going brown. Is there anything I can do to revive the plant? What are these toadstools? Will they endanger the rest of my plants? (e-mail reference)

A: Remove the spider plant from the container and cut away any rotting material. That is what the toadstools are feeding upon. Repot with fresh potting soil in a clean or new container that is free-draining. Spider plants are tough, so it should recover.

Q: I found your Web site and was trying to get an answer to the problem I am having with my tomato plants, but I did not find one. I’m hoping that you will answer my question in an e-mail. I have two tomato plants that I just planted. Since then, the plants have been getting tiny holes in the leaves. It looks like something is eating the plants. Any help that you can give me for this problem would be great. (e-mail reference)

A: See if you can find the insect that is doing this and get it identified. You can spray with a pyrethrin insecticide, but the insect has to be present to be effective. If the plants are otherwise healthy and the holes have stopped showing up, then I would do nothing at all except to wait to harvest some fresh fruit.

Q: When is the best time to move coneflowers to a different part of the garden? (e-mail reference)

A: Wait until the first hard frost of fall or move them early in the spring after the frost leaves the soil.

Q: I'm hoping you can help me. I purchased a white birch tree. After a week or so after planting, the leaves turned yellow and started to drop off. (e-mail reference)

A: If you are keeping the soil moist, but not soggy, the tree should be alright. Check to see if your tree is getting new growth with normal foliage. The leaf drop should be coming from the older leaves and is likely a reaction to transplanting.

Q: I have three varieties of irises. Two of the varieties do not stand up well. One variety of plants is standing very nicely. Some of the ones that don't stand up are almost lying on the ground. I thought it was because they are close to the house and catch too much wind or something. However the plants that stand up well also are against the house, but just a little farther down. Any ideas about what is wrong? They are growing very densely, so cleaning some plants out is on the schedule for this fall. (e-mail reference)

A: It’s a good thing to have the cleaning out of some plants on your schedule. Iris plants should be thinned out every three to four years. It depends on how much the plants have spread and how thick they get. Cleaning them out will make the difference.

Q: I have read a lot of your Web site information on nonflowering mock orange bushes. Mine is in morning and noon shade. Would you know why it did not flower this year? My husband does fertilize our lawn. Could that be the problem? I have fed it rose food. It is next to a Keria Japanica shrub that flowers profusely.

A: Sometimes mock orange shrubs are fickle about flowering, but I don’t know why. I do know that overfertilization of some plant species can inhibit flower bud setting and keep the plant in a vegetative state. I would recommend no further fertilization to see if that brings it around for next season.

Q: The previous owners of my home planted a devil’s corkscrew in the backyard. I am desperate to get rid of it. The roots have spread throughout my lawn and are sending up suckers all over. These suckers grow into small trees rapidly. Fortunately, they are very soft and easy to pull out or snip off. The darn thing is so invasive that it's a big job keeping up with it. The more I prune the tree back, the more suckers that come up. Do you happen to know how I can get rid of it? I fear that if I just cut down the tree, the roots will send up even more tenacious suckers. Since the tree propagates itself through the roots, chopping it down does not seem like a viable solution. I'd be grateful for your advice. Is there something that could be injected into the tree that would travel through the roots and terminate it? (e-mail reference)

A: Get some Roundup and spray or wipe it carefully on the foliage of the plant. It will be translocated and eventually kill the plant, roots and all.

Q: We bought a home with five beautiful, huge white oak trees. We live on a pond and have some wild land along the border of the pond where the brush is thick and a variety of trees are growing. I noticed four oak saplings growing in this area. The saplings range in size from just a few feet to about 7 feet. Should I try to transplant these trees into a better location or just let them fight it out with all the other trees and brush? I’d love to give them room to grow, but I’ve read on your Web site that oaks don’t transplant well. Any advice? (e-mail reference)

A: Leave the oaks alone and thin out the surrounding shrubs. The oak trees will have a better chance of surviving that way than digging them up would.

Q: We have four aspens that were planted in the last two to three years. One of the trees has sap damage in a number of areas. It has leafed out and looks healthy otherwise. The damage looks like a hole in the trunk and on some branches. The tree is black around the areas with sap. Some holes have stopped flowing. The other aspens do not have this problem. We want to plant more aspens, but are afraid they might die. Is it worth trying to plant more trees? (Fargo, N.D.)

A: Generally, aspens are pest free for several years if planted in a healthy landscape. It sounds like some borers might have gotten started on the problem tree. That would explain the sap flow. Left unchecked, the borers will kill the tree. If the tree is not in too bad a shape, you might want to consider obtaining some Bayer Advanced Tree and Shrub Insecticide. It is a systemic material that you could apply on all the trees, but concentrate on the one showing the symptoms you describe. The treatment gives 12 months protection, according to Bayer. This might be all you need to do to get it past this stressful stage.

Q: My strawberry patch is infested with Canada thistle! Last weekend, we pulled about 2 bushels of thistle and destroyed it. I know that is a very temporary fix. I plan to treat the devils with Roundup as they emerge. I thought that wearing a Jersey (cloth) glove over rubber gloves and stroking each plant carefully might eradicate the weeds, but spare the plants. Have you heard of this? I’d like to save the strawberries, but my only alternative would be to kill the entire patch and start over next year. (e-mail reference)

A: The treatment you describe works, according to what many people have told me. Controlling thistle is an ever-vigilant task, but if you can get them eliminated completely, you should be thistle free for years, unless you are surrounded by property that has these invasive beasts growing!

Q: I am having trouble with my geraniums. I believe they are called Johnson blues. One plant I kept in a pot in my garden window all winter, but put it in the ground in the spring. It looks very healthy, but there's not a bloom to be found. It's been in the ground about six weeks. My other Johnson blue had lovely blue flowers, but when I put it in the ground the new flowers came out pink! Could it be a soil variation causing the flower color to change? (e-mail reference)

A: Soil pH could be the reason for the color change. As for the one that is not flowering, be patient. It will flower when it is good and ready. However, I’m assuming you have it in ample sunlight.

Q: We have two crabapple trees (dolgo). The trees have produced an enormous amount of blossoms and apples every year. This year, one tree had just a few blossoms. The other tree had none. However, they look very healthy. The exception is the trunks. They look like a woodpecker was at it. I know there wasn't a woodpecker, but I don't know how else to describe it. There are holes in a row around the trunks. (e-mail reference)

A: That is normal for a crabapple tree, especially the dolgo. Be thankful the trees took a year off from bearing all that messy fruit. The holes are from a sapsucker, which is a type of woodpecker. Instead of pecking out a hole in the tree to raise a family, these characters pick on trees to get the sap flowing. The sapsuckers feast on the sap and any insect that the sugary sap may have attracted. This is nothing to worry about!

NDSU Agriculture Communication

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