May 10, 2001

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: Our problem is deer. There are herds of them roaming the area. Zoning laws regulate maximum fence height to 4 feet. Almost any plant or shrub we landscape with quickly becomes deer fodder. What would you suggest, either plant and shrubwise or repellantwise? (E-mail reference, South Salem, N.Y.)

A: Here is a list of "deer resistant" plants for you to consider; note, I said "resistant," not proof. Select from this list of plants to minimize deer browsing: spruces, pines, forsythia, spirea, lilac, lantana, yarrow, hollyhock, astilbe, coreopsis, foxglove, iris, bee balm (Monarda spp), ornamental onions, marigolds, daffodils, Russian sage, and verbena. Some herbs also show some resistance to deer - sage, thyme, chives, mint, and oregano. Sometimes the use of predatory urine (dog, wolf, mountain lion, etc) will dissuade deer from visiting your property, but the disgusting stuff must be applied frequently to be effective. A general repellent spray of chile pepper, garlic, and eggs is available on the market as well, and if applied to the new growth will keep them off your plants. All of these things work up to a point, depending on the starvation level and herd mentality. I have seen them clean out an area like a swarm of locusts, and in other cases, pick and choose.

Q: We recently had two 40 foot black walnut trees removed that were about 15 feet apart. We would like to plant a blaze maple next to the site of one of the black walnut trees. Do you know if the blaze maple will grow on the site, or might it be impacted by the black walnut toxins? (E-mail reference)

A: Good question. There has never been any documented research showing the allelopathic effects of black walnut on anything other than members of the tomato family. You will have a greater allelopathy on the tree you plant if you allow any turfgrass sod to grow within 12 inches of the trunk of the tree you are intending to plant. I would say go ahead and plant the maple.

Q: I am very new to houseplants and I have a question about a spider plant. This plant is large and is very heavy. I am afraid that if I hang it from my ceiling it is just going to pull the hooks out and land on the floor. My mother suggested halving it and repotting the halves. Is this a good idea and, if so, how do I do that? (E-mail reference)

A: With a good, sharp knife, and yes, it is a good idea. These are tough plants, you don't have to worry about killing them.

Q: For the last two years, I have had plenty of blooms and healthy looking vines, but very few cucumbers. Can you tell me why with so many blooms, the production is so low? Out of nine hills, I barely had enough to eat, let alone for canning. The zucchini did fairly well. (E-mail reference)

A: Try another variety or at least a couple of different ones. It may be that you got stuck with a bunch of male flowers that will not produce anything. If the same thing happens again this year, look for the male flower and move it to the female blooms for pollination. The female flowers are the ones with little cucumbers attached. What you are actually seeing is an ovary, the basal portion of the pistil. If this does not get fertilized it withers and dies; if it does it develops into a cucumber. It could also be that you had low pollinating insect activity at the time due to weather conditions.

Q: If I cut a limb off of a birch tree, do I need to do anything with the stub that I have on my tree? (E-mail reference, Barnesville, Minn.)

A: When you cut the birch tree branch back, expect to see quite a bit of sap flow. This will not hurt the tree in any way, so don't worry about it. The later you can wait to cut it back, the less it will "bleed" and will possibly be less messy. There is no need to apply a wound dressing; in fact, doing so will only slow the healing of the cut. Be sure to cut back to just outside the "collar" (about 1/4 inch) where the branch comes off the trunk. You don't want to leave a "stub," nor do you want to cut back into the trunk.

Q: I have this moss that is growing along the drip line on the north side of the garage. It has spread to a width of 2 feet, choking out the lawn grass. I tried spraying with copper sulfate and it did not work, but maybe it was not mixed correctly. What should I use to kill this moss? (Napoleon, N.D.)

A: Moss is usually indicative of poor nutrition, wetness and shade. Control involves pruning low branches for better sunlight penetration, reducing irrigation cycles to reduce moisture, power raking and/or core aeration to improve water infiltration, and applying of superphosphate (0-20-0) at 3 to 5 pounds per 1000 square feet to kill the moss. Bring the nutrient status up to par with a complete fertilizer and re-seed with the appropriate mixture, which would have a high percentage of fine leaf or creeping red fescue in it (at least 55 percent).

Q: I am concerned about a flowering crab that we planted in the summer of 2000. I'm not sure how old it is, but it is a very young tree, only about 6 feet high with just a few branches on it yet. At the end of February, a friend of ours was snow machining on our property, which is adjacent to the bush. He thought that the "stick" poking through the snow was just a scrub tree, and ran over it twice with his machine. Although the tree was bent right over against the snow, it didn't break and is still standing straight and tall. My concern is that the snow machine rubbed off some bark in several places. The reddish outer layer is gone and I can see green wood where the scuffing occurred. What do I need to do to protect the trunk and keep out any disease or insect infestation? (E-mail reference, Atikokan, Ontario, Canada)

A: Actually very little. No covering should be placed, nor any sealer placed over the wounds. I would suggest keeping them open, but "clean them up" by cutting away any torn bark, back to where it is attached, with a sharp knife. Encourage vigorous growth of the tree this spring, with adequate water and nutrients - not excessive - and the bark will begin healing over the wound. The tree actually "compartmentalizes" the wound to keep it from becoming contaminated with decay organisms, so the role of the gardener is to facilitate that action. Covering it or sealing it only inhibits what we want the tree to do. Put a big flag or fence around the tree next winter!

Q: We are planting a clump of three birch trees. How do we space these when we plant them to form a nice clump without overcrowding each other? Do they lean as they grow normally or do we have to lean them as well when planting them? I believe they are paper birch because we want the white bark. We do have a spot picked out with no overhead wires, about 30 feet from the house and on the east side. They will be about 15 feet from the road. (E-mail reference, Eastham, Mass.)

A: Don't worry about overcrowding them. Just work them together to the best of your ability, and plant them with no more than about an inch of soil over the roots. They will do much better if you plant them in a bed, or at least plant a herbaceous ground cover at least 18 inches around them. Do not let turfgrass encroach, or simply plant them into the middle of a lawn. The turfgrass has an inhibitory effect on the growth of trees. Keep the trees moist, not soggy. What happens is the trees will naturally root and stem graft together, making the "clump." Even though you are in a high rainfall area of the country, monitor the soil moisture, as these species do not like extended periods of drought. If you go more than two weeks without rain, water them well, no matter how old they get to be.

Q: I have an empty spot in a single tree line south of my house that has a sewer line that runs 4 feet below the surface. I would like to fill it in with either an ornamental grass bed or a fast growing, inexpensive tree, something for privacy from a well traveled road that goes past our yard. Can you give me some suggestions on different plants whose root systems do not run deep to interfere with the sewer line and that are perennials, that are fast growing, that do not spread uncontrollably, have some height and are pleasing to the eye? (E-mail reference, Jamestown, N.D.)

A: Given my choices, I suggest ornamental grasses: big bluestem, switchgrass, Indian grass, giant miscanthus, miscanthus silverfeather, and Karl Forester feather reed grass. All range in size from 5 to10 feet and have proven to be hardy in zone 3. Any or all should do well at your location.

Q: I have a variety of apple trees (Granny Smith, Red Delicious, Yellow Delicious) probably about five years old. One of my Red Delicious trees has a couple of branches with a powdery white substance, and when you wipe it off it turns a reddish/brown color. This will be the first year that some of the trees are flowering. What do you suggest to control this type of fungus? (E-mail reference, Charlotte, N.C.)

A: I am afraid that the white substance you are referring to could be a family of soft scale insects deciding to take up residency on your tree, and the reddish-brown stuff is the blood from the crushed bodies. You should be well past the blossom time for the tree. If you can get some horticultural oil, spray it carefully on the affected areas that you can find. This is a light-weight oil that will not burn the foliage (follow label instructions!) when properly used. It kills the insect by cutting off the oxygen supply and is not an environmental hazard since it is usually composed of vegetable oils. There are other more potent materials you can use, but with an edible crop like apples I don’t like to recommend them unless absolutely necessary.

Q: I have a whiskey barrel planter that holds water during the summer rains and drowns my plants. What sort of dirt mixture should I be using so it drains properly? (E-mail reference, Fessenden, N.D.)

A: It’s not so much the soil but the need to drill holes in the bottom of the container. If a whiskey barrel will hold whiskey, it will certainly hold water! Then, once the holes are drilled, back fill with a sandy loam--you should be able to feel the grit from the sand--and your problems with water accumulation should be over.

Q: I would like to grow some fruit trees from stones. Is that possible ? If it is, what is the best way to germinate and grow them? We just built a greenhouse this winter, if that would help in the process. (E-mail reference, Salt Lake City, Utah)

A: The more information I have, the better I can help. Thank you. Stone fruits ( plums, peaches, etc.) have a very hard endocarp (outer shell) that at one time was thought to inhibit germination, but in research studies the germination percentage was actually higher with the endocarp intact. Apparently the embryo was damaged in some instances during removal of the hard outer shell.

Except for the southern species of Prunus, all require a cold stratification period of about 90 days. This is accomplished by placing the stones in a moist mixture of 50/50 sand/peat at about 40 degrees F. This is easily done in the vegetable crisper of the refrigerator. Some germination should be evident at the end of this period. If not, keep the stones in there for another 10 to 20 days, or until germination is evident. From there, it is simply a matter of potting the sprouted seeds up and growing them on in your greenhouse for a season, then allow them to go dormant and harden off. You should have a decent crop of stone fruits in a few years.

Q: I am hoping you can give me some information about my Scotch pines. Several have needles which are turning red, or complete trees which are red. I have also noticed during my commute other Scotch pines looking the same. Is it hopeless for these trees, or is there something we can do? (E-mail reference, Enderlin, N.D.)

A: There is nothing you can do but wait at this point. The damage has already been done, and it now depends on how extensive it is and the vigor of the tree prior to the damage. If by the first of June no new growth has shown up then the tree(s) is likely dead and should be removed.

Q: I just talked to someone who has 30 roses lining the driveway. Every plant has what she described as small "beets" or nobs on the stems and all the way down to the base of the larger stems. She pruned them off when they first showed up last year and sprayed with a systemic insecticide. What's next? Total removal? (E-mail reference, Minot, N.D.)

A: Yes, unfortunately. This rose crown gall, caused by a bacterium. No cure, so the infected stock has to be dug out and destroyed.

Do you have a gardening or houseplant question? Write to Hortiscope, Box 5051, NDSU Extension Service, Fargo, ND 58105 or e-mail to Ron Smith at ronsmith@ndsuext.nodak.edu. Note to e-mail correspondents: please identify your location (city and state) for most accurate recommendations.

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Source: Ron Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
Editor: Gary Moran, (701) 231-7865, gmoran@ndsuext.nodak.edu