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

By Ron Smith, Horticulturist

NDSU Extension Service

Q: We have a cottage in northern Ontario. On the property are 20 blue spruce trees. The trees have branches growing to a few feet above the ground. This makes it difficult for us to mow under the trees. Is it OK to trim the bottom branches? We love these trees, so we don’t want to do anything that will hurt them. (e-mail reference)

A: No problem with trimming the branches. It’s called "miniskirting" the trees. Cut the branches off with a pruning saw or loppers. Cut back to the trunk, but not into the trunk. Sounds like a beautiful place to escape to.

Q: I have some lovely tulips that I let produce seeds this year. What do I do with them now? This is all new to me. I have planted many annual seeds and bulbs with good success. I would love to have these seeds develop. It is such a kick for me to grow all this stuff. (Flesherton, Ontario)

A: Sow them this fall before the snow and cold arrive. Cover the seeds with 2 to 3 inches of loamy soil. They should pop and grow for you next spring, but won't produce flowers. Allow the foliage to die down normally, then dig them up and reset them next fall, but this time plant them a little deeper.

Q: Is it all right to plant peonies around trees? I have a medium-sized red maple that would look really nice with peonies around the base. (e-mail reference)

A: It’s done all the time, so go for it!

Q: I bought some nice looking rutabagas from a farmers market. When I got home I cooked some, but they had a bland taste. Are there different kinds of rutabaga or do I have to let them set for a period of time? (e-mail reference)

A: There are different varieties of rutabagas. Could it be that you had turnips?

Q: I was told that striking a tomato plant with a limber branch encourages it to bloom. Is this true or false? I have not found any information to confirm or invalidate the statement. (e-mail reference)

A: Any movement will help pollinate the flowers. It can be on a trellis, vined up some bailing twine or vibrated with an old electric toothbrush. Commercial tomato growers are aware of this.

Q: I am looking for some tree wrap that is long-lasting and white. Do you know where to get some white drain tile or something similar? (e-mail reference)

A: Any of the big box or farm supply stores should have something.

Q: I have two beautiful paper birches that I purchased last fall. During the leafing process this spring, the trees leafed out, but only half way up. Is this a sign of bronze borer? Is it lack of root growth or water? (e-mail reference)

A: It could be a very strong symptom. It’s easy to determine by closely examining the upper part of the trees where the foliage ends. You should be able to locate D-shaped holes (small) or a swelling. The swelling would indicate that the borers are active under the bark. If it was a water or root problem, the entire tree would be affected.

Q: We have several green ash trees on our campgrounds and office lawn. However, the trees appear to be dying. They started to bud and some actually got leaves, but the majority only has small buds. Can you tell me what might be wrong and if they will come back next year? I hate to take them out if they may come back. (e-mail reference)

A: I seriously doubt they will come back next year. Leaves are necessary for food production. When they are gone, no food is produced, so the plant dies. If this is affecting all of the trees in the same manner, then my first suspicion is an environmental event happened, such as spray drift, soil migration of a herbicide or vandalism. If it is selective, then it might be a vascular disease, such as verticillium wilt. If there are holes about the size of a 22-caliber bullet in the trees and you live anywhere near the state of Michigan, then it could be emerald ash borer. I suggest you get someone from the Forest Service, Extension Service or International Society of Arboriculture to check what caused their demise. If it is emerald ash borer, then the trees have to be removed and the wood burned right away. The area also would be placed under quarantine.

Q: I live in Regina, Saskatchewan. I have a beautiful crab apple tree. However, I have not been able to use the fruit for the last three years because every apple is being destroyed by worms. The outside looks OK for most of the summer, but then the worms hit. (e-mail reference)

A: The time to spray is at blossom drop. As the flower petals begin dropping, apply the appropriate insecticide for your region and again 10 days later. This should take care of these pests, which are likely apple maggots. The apple maggot eggs are laid by flies on the developing fruit.

Q: I just purchased some property that has a small raspberry patch. I got a nice crop in June and am now getting another one. I've been told that these are everbearing raspberries. I've never maintained a patch before, so I am looking for some help in trimming and controlling weeds. I trimmed the dead stems to the ground, removed the weeds. I plan to trim the other stems to about chest high next spring. I was told to do it this way so I wouldn't lose my June crop. Is this correct? Also, is there anything that I can use to control grass? I think it is grass from the lawn that is spreading into the patch. If I get rid of all of the grass, would it be helpful to put down a shallow layer of wood chip mulch or would that be harmful to the raspberries? (e-mail reference)

A: The person who told you what to do gave you the correct information. It is what I did in another life as a small raspberry farmer and do it to this day with my raspberry patch. To control the grass in your raspberries, you need to use a product that contains sethoxydim as the active ingredient. There are several brands on the market, but check the label to be sure that raspberries are one of the approved crops.

Q: When is the best time to fertilize flowering crab trees? They were moved a year or two ago and were doing fine, but now look a little sick. They look as though they are losing leaves and some of the smaller branches are drying up. (e-mail reference)

A: Tree fertilization is done in early spring. You can download the basics of doing so from my Web site at http://www.ag.ndsu.edu/pubs/trees.html. Click on H1035 and download the version you want.

Q: Last summer we bought a hibiscus that had beautiful green leaves and flowers. We brought it in for the winter and it seemed OK. In early spring, we set it out on a nice day, but evidently it got too much sun, so it dropped almost all of its foliage. It had one stalk that did stay and kept growing. We finally pruned most of the one stalk back and carefully put it back outside. It’s full and green, but does not have flowers. Any ideas how to make it bloom again? (e-mail reference)

A: They flower on new growth as long as it isn't overfertilized. Have a little more patience.

Q: I have a medium-sized boxelder tree. It bears seeds, so I guess it’s a female. The problem I have is that there are a lot of small, dead branches on the ends of the long, large branches. I pruned the tree two years ago to take out a lot of the dead sticks. The pruning did make the tree look healthier. However, it seems that a lot more dead sticks are developing. Is this normal? The leaf color and shape of the tree look normal. (e-mail reference)

A: Unfortunately, yes it’s normal. This is one of the reasons we like to keep them confined to shelterbelt plantings.

Q: Would it be wise to use creeping Jenny in the dirt openings of a rock wall to keep the dirt in the crevices? Do you think it would spread beyond the wall? Is it a perennial or does it come up from seed? (e-mail reference)

A: I would suffer too much guilt recommending anything like that for your planting! You can use plenty of rock garden plants rather than capitulating to this lowly weed that would cover everything and then some. Visit a local garden center and look for sedum, hens and chicks or creeping phlox to do the job.

Q: A landowner in central South Dakota wants help with the prickly pear in his yard. I've done some research on the Internet that recommends using Tordon or Surmount on pasture or rangelands. Can you provide any recommendations for use on lawns? (e-mail reference)

A: The product known as Trimec will control this invasive pest. Apply according to label directions.

Q: I have a nine-year-old red dragon Japanese maple tree. We are moving to a new location in the same city. How do we move the tree? (Macedonia, Ohio)

A: Give the tree's beautiful red foliage a kiss goodbye and wish it well under the new owner's tutelage. Japanese maples do not transplant well and a tree this age would stand little chance of surviving at a new location. You might as well put a new tree on your list of needed items for your new home. Sorry!

Q: I have a producer who has asked me about planting blueberry bushes in western North Dakota. I'm not sure where she got the bushes. Can you give me any information? (e-mail reference)

A: She must be mistaken unless she has a peat bog with high acidity on her property. Generally, blueberries are not recommended for our area because of the soil type and temperature extremes. Consequently, I have no valid information to pass on.

Q: Last fall I collected several Colorado spruce seeds from the surface of our driveway in central Minnesota. Before the ground froze, I planted the seeds over a square yard of tilled soil that gets direct sunlight. I varied the depth of the seeds because I wanted to make sure that some would sprout. I also placed fencing around the area to keep rodents and rabbits out. However, the only thing that grew was the weeds. Are there some steps I missed or are there particular soils or moisture levels that work better for promoting growth? The area where they were planted contained several inches of black topsoil. I have several Colorado spruce and white spruce comingled as a windbreak and natural fence on the edge of our property. Colorado spruce is a denser and fuller tree than any of the white spruce. I noticed that you prefer Black Hills spruce. Does this spruce have dense foliage and a similar columnar appearance when mature? Would it be better to get some Black Hills spruce seedlings for the edge of the property? (e-mail reference)

A: Collecting the seed at just the right time is of utmost importance in getting viable seed. Even at the perfect time, set low expectations. Collect cones shortly after the male pollen is shed and store them in a cool location. It is at this point that the spruce seed is most viable and can be sown in a full-light location with no pretreatment. Usually, there are a high percentage of empty seeds in any spruce seed lot. The heavier seeds are more likely to germinate. If you wait until fall to collect the seed, assuming there are any remaining, it is likely that these are blanks because the wildlife in the area is smart enough to pick out the plumper, heavier seeds for a meal. I would suggest making a small bed of pasteurized soil to sow the seeds in. When germination and the first leaves appear, transplant them to the desired location. I like the Black Hills spruce for a number of reasons. I used to be in the landscaping business and hated planting blue spruce because of the hypodermic needlelike foliage. Blue spruce is a grossly overplanted species, which provides good opportunity for disease and insect problems. Blue spruce have too much of a "cookie cutter" architecture. Black Hills spruce has some variability, softer needles and I like the darker foliage in the landscape.

Q: My daughter is studying our plum tree for a school project. The plums are a lovely purple, but she has noticed that many of them have a brown patch on the skin that is rougher than the skin, almost scarlike. Could you tell us what this is because she would like to put it into her work and I also would like to know? (e-mail reference)

A: This roughness on the skin in spots is almost always caused by environmental conditions and not a disease or insect problem. It could be caused by wind blowing the fruit in such a way that it rubs against other fruit or branches, hail, a touch of frost or cold weather at the time of fruit development or sudden swings in temperature. Sometimes corky growth is just beneath the roughed skin. It can be cut out and the plum used for consumption.


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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