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Hortiscope

Ron Smith answers questions about plants, trees and gardens.

By Ron Smith, Horticulturist

NDSU Extension Service

Q: We have a large flowering plum tree that seems to be healthy. It normally has a large amount of blooms in spring and produces many small fruit. However, we don't eat the fruit. For the last month or two, I have noticed a lot of sticky residue on my vehicles parked in driveway. I have traced it to the tree. The tree has clear, sticky residue on its leaves. The tree seems to be healthy, although this year it did not produce much fruit. It is bothersome only because the residue gets on the vehicles. Does this make any sense? (Albuquerque, N.M.)

A: You have an insect problem. The insects are secreting honeydew from their feeding activity. Since you don't eat the fruit, I suggest using a systemic insecticide, such as Bayer Advanced Tree and Shrub Insect Control. It will kill the insects as they feed and not harm the friendly nonplant destructive insects. Since winter is right around the corner, I would wait until next spring's thaw to make the application. Be sure to follow label directions.

Q: I want to thank you for your Web site on arborvitae issues. I had 30 pyramidal arborvitaes professionally planted in May. Every month I have had issues. I have been to my local Extension office. At first, I was told I had three insects, which I have eliminated by spraying. Then I was told it was a fungus spore, so I have sprayed all summer to take care of that problem. I thought I had the problems under control. However, I now have at least eight arborvitae trees turning from yellow to brown. However, the problem appears to be mostly on one side of each tree. What could be causing this? Could it be a fungus or twig blight? Will the problem spread to the other trees? Will this kill my trees? What can I do to remedy this? I should mention that the affected trees are very close to four pine trees. Could the pine trees be shading my arborvitaes too much? (Pittsburgh, Pa.)

A: The shading from the pines, as well as exudates from their roots, may be a major contributing factor to your arborvitae problem. Have the folks who planted the arborvitae had anything to say about what is going on? On-site visits usually clear things up quite easily. If you cannot get the people who planted them back for a visit, get a hold of the Extension Service horticulturist at Pennsylvania State University to see if he or she can provide some assistance. You may be asked for some photos or a soil sample to confirm any suspicions the horticulturist may have. There are some excellent folks at PSU Extension, so I wouldn't hesitate to contact them. Thanks for the nice comments about the information on the arborvitae Web site! It is appreciated.

Q: Have you ever run across anyone who has an aloe vera plant that has blossomed? My plant has been blooming for a few years. This year, it has three pods on it that I don't know what to do with. Do you have any suggestions? (Jamestown, N.D.)

A: No, I don’t. You can cut them off and toss the pods or remove them and allow them to dry. After that, harvest any seed that may be in the pods and sow the seeds. Hope for the best after that.

Q: We lost six trees that flanked our driveway due to hurricane Ike. We didn't plant the trees, so we don’t know what they were. We found a tag on one of the branches that said it is an Alamo italica. We took a picture and the tag to several nurseries in our area, but nobody had ever heard or seen this type of tree. We really would like to replace these trees with the same type if possible. On the back of the tag, there is a list of outstanding features. It says the tree is picturesque, tall, columnar; has shiny, dark green foliage; and is particularly effective for formal planting. Any information will be greatly appreciated! (Montgomery, Texas)

A: This is just another name for the Lombardy poplar. It has been called many names, but this is the first time I've heard it called Alamo italica. It probably originated in Texas. Sorry hurricane Ike was so destructive to your trees. I hope your home is OK. If you cannot find these exact same trees, there are others to consider that have the same growth characteristics. You might consider the upright columnar European hornbeam and, for sure, the upright or fastigiate live oak.

Q: We won 15 bur oak saplings at a fundraiser. We would like to put them on lake property we purchased in the Turtle Mountains. Since we are in the process of building a cabin there, we would rather postpone planting the trees until the building is up and the yard is in order. We planted the oak trees in a garden spot on our farm. We have a large garden area that is quite protected by trees and has very good soil. We would like to transplant them next summer after our building is completed. I read on the Internet that bur oak does not transplant well due to its deep taproot. Should we plant them at the lake and hope they aren’t crushed by construction equipment or not get watered enough? I would appreciate your advice. (e-mail reference)

A: If you can dig them up now and get them situated where you want, it would be the best for their chances of surviving. Mark the trees in some way or fence them off. For sure, show the building contractor where the trees are planted.

Q: I have a good-sized, healthy jade plant. Can this be planted outside or will the winter cold kill it? (Denver, Colo.)

A: Absolutely, without any doubt, the winter cold will kill it! Keep it indoors.

Q: I moved into a new house that has a birch tree that hangs over my driveway. For the past four weeks, I’ve noticed what looks like misty rain on my windows. It won’t come off when I wipe it. Is this sap from the tree? How long will it last? (e-mail reference)

A: This sap is coming from the tree through whatever insects are feeding on it. Look for aphids or scale insects. Since it is so late in the season, I wouldn't recommend attempting any kind of control right now. Let the colder temperatures of winter close the insects down. Next spring, look for Bayer Advanced Tree and Shrub Insect Control. It is applied as a drench at the base of the tree. Apply it when the soil thaws and as new growth is beginning. You will not have any insect problems for the rest of the summer!

Q: I bought five tuberous begonias last summer for my mother. Her home faces north, so we haven’t been able to find many colorful flowering plants to put there. The begonias were beautiful. I would like to lift them and set them out again in the spring so we can enjoy them next year. Could you give me specific directions on how to do that? (Cooperstown, N.D.)

A: Impatiens also do well in the shade, as do lady’s mantle and astilbe. Sprinkle in some coleus (keep the insignificant flowers pinched off) and you'll have a very good color impact in the shade. Certainly don't overlook the wax begonias for a splash of color! To save the tuberous begonias, there are a couple of approaches to consider. The most challenging is to dig the plants up and bring them indoors for use as houseplants. Keep them under light for 12 to14 hours a day. The other approach is to allow a light frost to bring everything to a stop. Then bring them indoors, shake off as much of the soil as possible and allow them to dry for seven to 10 days. Remove any excess soil and foliage. After that, store the plants in sphagnum peat moss, sawdust or powdered sulfur (or use a combination) at a cool, dry temperature. Repot in early spring and keep warm at 68 to 75 degrees. Move to a sunny spot when the shoots appear. Keep evenly moist, but not wet. Plant outside after the danger of frost has passed. As a very broad generalization in anticipation of more questions about tender bulb storage, keep them dry and above freezing. Don't store the bulbs in airtight containers (brown paper bags are best). Doing that could cause moisture buildup that may cause rot or fungus. Check regularly for desiccation and mold. Remember to label the bulbs by type and color.

Q: I live in northeastern North Dakota. I will be hauling in dirt to fill in a few low spots in my yard. Can grass be planted this late in the fall or should I wait until spring? Also, deer have stripped the lower branches of several evergreen trees. When is the best time of the year to remove these branches? (e-mail reference)

A: Go for the grass planting this fall! This is considered dormant seeding. The seed goes through a priming process where Mother Nature provides some water that the seed takes in, but because of low temperatures, the seed doesn't germinate until spring. Then the seed explodes out of the ground! As to the deer damage, get the trees pruned back as soon as possible after discovering the damage.

Q: I am moving four blue spruce trees that are in great shape. I am renting a tree spade from a tree company to do the work. However, is it too late in the year to move these trees? (David City, Neb.)

A: Absolutely not, so go for it! Water them in well at the time of planting and that should be it!

Q: I just bought two autumn blaze red maples. How can I be sure that they are hybrids? I live in Spring, Texas. Will these trees do well in my area? (e-mail reference)

A: Look at the tags that should have come with the trees. They should read “autumn blaze” with a registered trademark by the name and the botanical name (Acer x freemanii) should appear on the tag as well. If the trees are not tagged or the tags don’t read as I said, then the person selling them is breaking the law and could face a very heavy fine. Houston is too far south for these trees unless you see others planted in the area that are growing. They are hardy from zones 4 through 7. Houston is in zone 9, which is too hot for too long for this particular plant. Where did you purchase them? I would think a reputable nursery would not sell something that won't thrive in its area. There are enough problems with getting adapted plants established without going out of the hardiness range.

Q: I am writing to you again about a problem with slugs in my vegetable garden. Last time, you suggested that I tempt the slugs with beer traps. I did put down the beer traps, but I never caught a slug. I purchased commercial traps and made my own. What I am doing wrong? Also, they seem to be getting worse. This summer, I found them in my flower beds, too. They are very damaging to the plants. I seem to have the best luck by putting boards down on the ground between the rows and going out each day to hand pick them. There are so many and so unpleasant, I can hardly eat the produce! Where do they come from? Are they deep in the ground or on top somewhere? How do I find the mother lode of slugs? I am beginning to get discouraged and am considering not having a vegetable garden next year. (Starkweather, N.D.)

A: The beer traps likely didn't work because the saucers have to be set into the ground so that the slugs can migrate into them and drown. Diatomaceous earth, rock salt, slug motels and copper wire are traps that have worked for an eternity, at least for some. You also need to back off on the watering somewhat because your produce should not be in a great deal of water at this time of year. Slugs are hermaphroditic, so only one needs to survive to begin a new brood. I hope this advice is encouraging. If this doesn't work, I suggest a raised-bed garden next year using designer soil to provide excellent drainage.

Q: I have a small greenhouse at the school I work at and have a question about our Christmas cactus. This plant is huge, but had a rough summer (too much sun, I think). It now has lots of healthy growth, but is long and spiky. The leaves are round, not flat, and are segmented, except for those at the base. The leaves are rather upright and are covered with lots of new roots at the very end. Can I plant these to propagate new plants? If yes, the leaf would have to be put into the soil upside down for the roots to be in the earth. I have not found any references to these types of roots, but understand that Christmas cactus normally is propagated with the traditional root side down. Any guidance would be appreciated. (e-mail reference)

A: Those are aerial roots that are common in the tropical forest where this plant grows. They thrive in the high humidity of the rain forests and in your greenhouse. You can plant the leaves as you normally would. Ignore the aerial rootlets coming out of the top. They probably will continue to develop, but don't let it bother you. Your cuttings also should develop roots as well on the other end. Many tropical plants develop aerial roots from their stems that function as stabilizers, as well as for water and nutrient uptake. Have fun.


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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