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Hortiscope

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

By Ronald C. Smith, Horticulturist

NDSU Extension Service

Q: I have a lacebark elm that is oozing on the northwest side of the tree. I had the same problem with a tree a few years ago. On that tree, the top started dying about June and by September, the tree was gone. An arborist told me the problem wasn't borers. The arborist said it was a bacteria and advised me to fertilize the tree and water it well. The tree survived, but it is doing the same thing this spring. I also treated the tree with a systemic insecticide for borers (just in case). Although it dries up for a couple of days, the oozing comes back. Any ideas on how I can save this tree? (e-mail reference)

A: If the problem is a bacterial infection as the arborist suggests, there is very little that can be done other than what was recommended. The idea behind this is to compartmentalize the infection and keep it from spreading. It sometimes works, but not with any dependability.

Q: I have a dieffenbachia in my house. After this winter, the plant started to spread. However, the stem of the plant is turning yellow and the area where the stem and the soil touch is soft. What can I do? I'm worried sick. The room lacks light and during the winter, the plant was in constant low temperatures. Is there a way to save my plant? (e-mail reference)

A: From what you tell me, the plant is a loss. You can try taking cuttings from the firm parts of the stem and cut them into about 4-inch lengths. Then get some sphagnum peat moss and spread it out in a flat. Be sure to soak it in water and then wring it out. Take the stems and barely cover them in the moss. Place the cuttings in a sunny location. Mist the moss daily to keep everything moist, but not soggy. In six weeks or less, you should see some leaves coming from one of the ends. Check the other ends of the cuttings. You probably will have some roots emerging as well. Carefully lift the cuttings out and pot them in commercial potting soil. Put the pots in a sunny location and keep the media moist, but not wet. The plants will grow nicely from then on, assuming you have learned your lesson from this experience!

Q: Your column is very informative and helpful. I purchased a purple leaf plum in February. The tree has bloomed with flowers and leaves, but about a third of the branches do not have any growth. Does this mean that those branches are dead or is there something I can do? Can this tree be saved? Can I prune off the dead branches? If so, when should I do it? (e-mail reference)

A: Those branches probably are dead. As for the rest of the tree, if it is healthy, there is no reason why you should lose it. The tree may have a weird shape for now, but if it is something you can put up with and train, your tree should be OK. You can prune off the dead branches. With dead material, the sooner it is removed, the better.

Q: I have an evergreen in our front yard (see picture). I would like to put a flower bed under it, but I have a few questions before I start. I've heard that some trees have shallow roots and digging around the tree to plant flowers can hurt the tree. There is a root running above the ground. There isn't much grass growing under the tree, so I'm wondering if it'll sustain any kind of plant life or is it too acidic? We have very sandy soil. Thanks so much for your time. I always enjoy reading Hortiscope. (McVille, N.D.)

A: Cut a few more feet of limbs from the bottom of the tree and you will be able to plant all the flowers you want. With a tree the size of yours, the surface roots will be damaged somewhat, but it won't be lethal. I have seen plenty of attractive flower plantings under huge spruce trees with no ill effects on the tree or flowers. Thank you for being a regular reader of Hortiscope and the nice comment about it!

Q: I have an apricot tree that has grown very large, but has yet to produce full-grown fruit. Last year I saw some fruit starting on the tree after it bloomed, but then nothing. I do not know if birds or bugs ate the fruit. I did not see any on the ground. This year, it has just started blooming. Is there anything special that I need to do to take care of it? (e-mail reference)

A: I am going to direct you to my Web site on apricot tree care at http://www.ext.nodak.edu/extnews/hortiscope/tree/apricot.htm.

Q: I have a question about spider plants. I gave one to my mother 18 years ago. Since she passed away, the plant has gone to my sister and now me. I do not want to kill it because it's old. It has lots of babies. Should I cut them off and root them? What is the basic watering and light care for spider plants? I believe it's still in the original pot! Should I transfer it? Some of the roots are sticking up above the dirt. (e-mail reference)

A: Leave it as is, but water it once a week or so. For more information on spider plants, go to http://www.ext.nodak.edu/extnews/hortiscope/houseplnts/spider.htm. There you will have almost every conceivable question answered. Enjoy.

Q: I spray my yard with Trimec for dandelion, clover and creeping Charley, but am not sure of the proper formula to use. Could you please advise me on the proper proportions to use? (e-mail reference)

A: All of that information is on the label. If not, go to http://www.pbigordon.com/pdfs/TrimecPlus-SL.pdf for more information. Be sure to follow the directions. Good luck!

Q: Last fall I asked your advice on cutting back my rose bush. I cut it back, covered it with leaves and bought a Styrofoam cone to cover the bush. I put a weight on the cone to anchor it against the wind. I need to know when to uncover it so the bush can get some sunshine and fresh air. As always, your valuable advice will be greatly appreciated. (Bordulac, N.D.)

A: Uncover it on a day there is sunshine and the temperature is above freezing. I wouldn't go too far with the Styrofoam cone in case the weather takes a sudden nasty turn, which will happen. Thank you for the nice compliment!

Q: I just wanted to let you know that hollyhock is extremely toxic/poisonous to dogs. Perhaps it is only toxic during the growing season, but not during the winter dormant season. My dog ate a root again today that about killed him. Just thought you would want know. (e-mail reference).

A: Thanks for the information. I'm glad your dog is all right. On matters like this, all I have are a few references, which are research-based and documented by veterinarians or the Poison Control Center. I would suggest ripping out the hollyhock because dogs can be very good companions and loveable to boot, but most are not very bright about learning from bad past experiences, such as chasing cars!

Q: You probably have received hundreds of letter pertaining to this subject, but I really need your help. I am being swarmed with boxelder bugs. I live on the east coast of Pennsylvania and have a natural buffer zone behind my property. I have attempted sprays, but must be careful about what I use because of the pets I have. I have searched the Internet and am totally confused. Every supposed expert has a different solution. I do not know what a boxelder tree looks like. Is this the only type of tree that the bugs come from? I am looking for the most natural way of getting rid of them. There are times my neighbor's house on the sunny side is completely covered and so is one side of my garage. (e-mail reference)

A: You are right, I've had plenty of inquiries, but yours is the first one for 2007! Congratulations! Other than hiring a professional pest control company, you could use the insecticide Sevin for control. They are at their worst now because the bugs are seeking warmth by collecting on the south side of buildings and also attempting to get inside. As the season warms up, they will not be such pests. If you choose to use Sevin, keep in mind that it has little or no residual effect, so the spray must reach the boxelder bug directly. As to whether or not they stay exclusively with the boxelder maple species, that isn't necessarily so.

Q: I noticed a few branches on one of our evergreens have turned red. Could it be due to blight? What can I do about it? I would hate to lose it. I enjoy reading your column. (e-mail reference)

A: I appreciate you being a loyal reader. I can't say for sure, but at this time of year, I would suspect that the discoloration is due to winter desiccation. It may or may not come back after spring finally gets here.

Q: I have sunflowers growing on the side of my house next to the foundation. They return every year by reseeding. The plants start to grow healthy, but as they get taller, the bottom leaves turn brown and dry up. This continues until the entire plant is dead. I do get flowers, but the plants die too soon. I think there is something wrong with the soil, but I don't know what to do about it. Do you have any suggestions? (e-mail reference)

A: There are too many sunflower diseases to single one out. The diseases include alternara, white mold, rust and more. I wouldn't keep the sunflowers in that spot any longer. Move the plants to a location that gets full sun and air circulation. If that is the only spot you can grow the sunflowers, apply a general fungicide every 10 to 14 days as they grow.

Q: I have an apricot tree that I planted a few years ago. This tree was recommended for the zone I live in. The tree has been a real trooper. It has borne fruit each year, except one. However, last year was the first time that all the apricots were infested with worms. Is there something that I can do to prevent this infestation from happening again this summer? It is just about spring here and I would like to help my tree to be fruitful and avoid the infestation. (e-mail reference)

A: If the tree has not started budding, go ahead and spray it with dormant oil. If it has started budding, then wait until the flowers begin to fall to start spraying with Sevin insecticide. Repeat the application at least three more times every 10 to 14 days. Of course, be sure to follow label directions for timing and concentration.

Q: I have two apple seedlings I got from planting apple seeds. Both have 10 to11 large leaves. Up to the ninth leaf, everything looked OK, but then both started to get brown, rusty edges on the older leaves. The new leaves have been coming out nice and green. I must tell you that I have been watering with added fertilizer. I use tap water if the plants need more watering during the week. Could I be using too much fertilizer? (e-mail reference)

A: You guessed it! Too much fertilizer is causing the firing of the foliage. Use tap water and forget fertilizing until you plant them outdoors and are at least a year or two old.

Q: I am not sure what type of arborvitae would give me the results I'm looking for. I have a retaining wall behind my property. The wall needs to be repaired in several sections. Above the retaining wall there are a number of old evergreen trees, which we plan to have removed. We would like to replace these trees with nice looking border shrubs, so we are considering some type of arborvitae. Some people have suggested green giant, but I think these would get too big. Your column mentions emerald, techny and Brandon. Since the wall slopes downward north to south into the primary privacy impact zone, we would like to have taller shrubs on the lower end than on the higher end. I think we would need a full-grown height of 12 feet or more at the lower end. The ground also slopes from the neighbor's driveway toward the wall, so those shrubs also would be planted on a grade. Could you suggest a variety that would be appropriate for this project and the sizes of shrubs you would plant? Although this is a suburban area, deer are a concern. Since I am investing $4,000 in fixing the retaining wall and $2,000 to remove the trees, I'd like my investment in arborvitae to be a sound one. (Pittsburgh, Pa.)

A: In another life, I used to live in the Pittsburgh area near the airport and had a view of the beginning of the Ohio River. I would advise purchasing the techny cultivar of arborvitae and a smaller-sized arborvitae as well. Of greater issue to me are the problem trees you have. As for the amount of dollars you are going to spend, be sure to check the pedigree of the people you are going to hire to do the work. They should be able to provide you with good references, which I advise checking on. Be sure they are adequately insured for any property damage that may occur.


NDSU Agriculture Communication

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