April 5, 2001

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: Will butternuts grow in our area? We have a few walnuts, horse chestnuts and an Ohio buckeye or two in the area, but that is about the extent of our nut crop. (E-mail reference, Williston, N.D.)

A: The butternut should grow in your area. It is hardy to zone 3. You are on the western fringe of its native range. Make sure the soil is enriched with organic matter prior to planting.

Q: In a recent Hortiscope you indicate that sunflower hulls are inert. Another horticulture specialist claims they contain an allelopathic substance that will inhibit growth of nearby plants. I know sunflower roots are allelopathic, and when we spread sunflower hulls at Crookston we could essentially sterilize the ground if we put them on heavy enough. Any thoughts? (E-mail reference, Beach, N.D.)

A: Well, that is interesting anecdotal evidence that something is working, either chemical or physical. A good little study would be to take water extracts from sunflower hulls and spray it over some soil to see if the same effect is obtained. I would really like to know, one way or the other.

Q: Can you tell me why the enclosed sample of ivy has curled leaves? I put it outside in the summer, and have never had this problem before. (Carrington, N.D.)

A: Curled leaves are often the result of aphids or other piercing/sucking insects feeding. There was no physical evidence of aphids on the sample you sent. You might have had some post aphid activity that caused this. Another possibility is some minute herbicide contact. This could come from drift or residual in a container that was used to water the plant. In all probability, your plant will outgrow this minor affliction.

Q: I had blight in my tomatoes the last two years . Now I am wondering if there is a disease resistant tomato plant out there. If I take out the top 6 inches of the top soil, will that be enough to plant them back in the same plot? (E-mail reference, Hoven, S.D.)

A: That's too much work! Simply order disease resistant tomatoes. Any of the All-America Selection winners are resistant. Incorporate generous amounts of peat moss into the soil; water only around the base of the plant, not on the foliage, and stake them to keep the foliage and fruit off the ground. If you continue to have a problem after this year, get into a three-year crop rotation; beans, corn, then back to your tomatoes. That often breaks the disease cycle.

Q: I would appreciate any information you could send me regarding native trees or trees that do well in the Midwest. I am specifically interested in Dutch elm disease resistant elms. (E-mail reference, Sioux Falls, S.D.)

A: The following elms have passed the test to date in our trials for DED resistance:

American Liberty Elm, Independence Elm, Jefferson Elm, Princeton Elm, Valley Forge Elm, Washington Elm, Sapporo Autumn Gold Elm, New Horizon Elm, Cathedral Elm, Vanguard Elm, Accolade Elm, Dandada Charm Elm and Triumph Elm. 

Other trees to consider are: 

'Stately Manor' Kentucky coffeetree (Gymnocladus dioica); Amur corktree (Phellodendron amurense); Ironwood (Ostrya virginiana); Laurel willow (Salix pentandra). (This is a "clean" willow, not the typical messy ones.)

Q: I understand you like the Autum Blaze tree. Would you tell me more about it? Is it easy to grow, and does it take special care? Are they fast growers? We lost one of our shade trees and another one isn’t long for this world. They would be planted on the west side of our house. We would like a fast grower that would last forever, not just a few years. We live in Davenport, Iowa, Zone 5. (E-mail reference, Davenport, I.owa)

A: Yes, Autumn Blaze is a favorite of mine. It is an inter-specific hybrid between between red and silver maples. It is fast growing, alkaline soil tolerant, and has beautiful red fall color. The canopy shape is oval and stays pretty much that way throughout it's life. It will get to be about 50 feet tall and about 35 feet wide. Since you live in zone 5, hardiness is no problem, as it is hardy even in the fringes of eastern North Dakota in zone 4. You should be able to find it in any quality nursery or garden center outlet. It might be listed under the cultivar name of Acer 'Jeffersted', after the gentleman in Ohio who developed it. Autumn Blaze is a trademarked name. Given just normal care in planting and maintenance, the tree should easily outlive the occupants of the house. I would strongly suggest that you purchase a container-grown specimen that can be handled by one or two people. I'm not a big believer in tree-spaded planted trees for residential landscapes. The investment is too high, and the plants often die out over a period of many years, whereas young, smaller trees take off and adapt to the site quite easily.

Q: I’ve heard that one can make an inexpensive insect spray by putting some liquid soap in water, using a spray bottle. Is this true? If so how much soap can one use in a quart without hurting the plant? I'm after the white flies on my hibiscus. How often should they be sprayed?

The hibiscus defoliated last month, but last week one had seven blossoms. Is it normal for them to cycle occasionally? (E-mail reference, Brookings, S.D.)

A: I do not recommend making up your own soap solution insect spray. The soap manufacturers are guided by economics for their formulations, not what would be good for plants or not good for insects. You could get something that would end up killing your plant. Formulations of insecticidal soap that are available commercially and safe for both indoor and outdoor plants. I suggest using that material to control your insects. Spray as often as necessary to kill the white flies. Good luck--they are tough ones to get rid of. I suggest cutting your hibiscus back--hard--to give it a resting period. Back off on the water for a few weeks, watering just enough to keep it alive. Then gradually increase the watering and fertilizing and new growth should begin to appear. Give it plenty of light; summer it outdoors.

Q: When we were in New Mexico last winter, I collected some Cholla cactus cuttings, thinking I could grow them as a house plant here. They didn't root, but the yellow ends of the cuttings released seeds when they dried up. Do you have any information on what conditions are needed to get these seeds to sprout? (E-mail reference)

A: About that specific cactus, no, but for cacti in general here is what is needed, and I don't see why it wouldn't work for your Cholla as well. Free the seeds of any pulpy material surrounding them. This may cause the seed to not germinate. They need light to germinate. Indoors, use fluorescent light, for eight hours continuously, with the soil temperature warmed into the upper 70s. They also need moisture at this stage, so keep them continually moist via misting. If nothing emerges in 10 to14 days, then either the seed is not viable, or they need another special treatment. This procedure works for about 90 percent of the cacti that I know of. If this doesn't work, then I'd suggest contacting the extension horticulturist at University of New Mexico in Las Cruces.

Q: I have a small schefflera plant in my office growing entirely under flourescent light. A few months ago someone apparently poured cola on the plant, judging from the smell of the brown water coming from the bottom of the pot. A peace lily and prayer plant were also in the pot, and neither of them survived this bizarre incident, but the schefflera did and is seemingly healthier than ever. However, it is doing something very strange. It is growing leaflets out of the tops of the leaves. It is almost unrecognizable as a schefflera anymore. The leaflets are generally single instead of in that configuration of five that they usually have, but one is tripartate like a clover leaf. Have you heard of this before? Is the plant OK? It seems to be growing vigorously albeit very strangely. (E-mail reference)

A: What was poured on your Schefflera was something more than Coke or Pepsi, or they are putting something in those soft drinks now that I don't want to know about! What you are getting as far as your "new growth" goes sounds very much like a growth regulator reaction. It was potent enough to kill the other plants, but not the schefflera, giving it the anomalous growth characteristics. This is the kind of college lab experiment that is carried on with growth regulators like 2,4-D, that belongs to the family of phenoxy herbicides. They create a hormonal-type of growth in broad-leafed plants in low doses and kills them in slightly higher doses. In the dose that your container received, it was enough to kill the other plants, while it is simply causing strange cell division in the schefflera. The schefflera may survive but look weird. Depending on the kind of folks you have in your office, it could be the subject of some lively conservation based on what people should and shouldn't do with their drinks!

Q: We are looking for evergreens for our farm yard and have an opportunity to acquire some from Ohio that we are not familiar with--Thuja plicata ‘Spring Grove’. Are you familiar with these trees, and what are your thoughts on growth success (with some winter protection) here in South Dakota? We have a deer problem here (even in our yards) and our relatives state these are supposedly "deer resistant." (E-mail reference, Miller, S.D.)

A: That cultivar of Thuja--'Spring Grove'--I don't have listed in any of my references, so it must be a relatively new introduction. Coming from a nursery in Ohio, I would say that you are safe in making the purchase for your location in South Dakota. These plants typically like moist soil conditions and will need some protection from winter's blasting winds. As far as "deer resistance" goes, it’s an easy claim to make. Just keep in mind that resistance is just that--not immunity.

Q: Thank you for your comments on terrarium building. However, I'm at a loss for which plants to use. My children are schooled at home and we are looking forward to putting a terrarium together. I'd appreciate any names of plants that would be best to use in Oregon. (E-mail reference, Ore.)

A: Terrariums are fun to make and observe during their grow-in. They are a perfect living microcosm of nature, but unlike natural settings, they do not have any drainage capabilities.

Here are the basic steps in building a terrarium: Obtain a clear glass container that has a top big enough to get the soil, plants and hands into. Line the container with activated charcoal chips, about half an inch thick. This makes up for the lack of drainage, keeping the air and environment smelling sweet and not septic. Next try to find a potting soil mix that is labeled "for terrariums only"; if not available, then obtain a good potting soil mix that has been pasteurized and appears to not be too rich, dense, or moisture retentive. If it does, then add some vermiculite or perlite. If you are not happy with any of the potting soils that are available, try to get one of the soilless mixes. There are two basic ones on the market, the Cornell Mix or the UC mix from the University of California. You can probably have better luck getting the UC mix in your part of the country. It is sold under the names "First Step" and "Super Soil." Whatever you use as your soil, make sure it is at least 1 inch thick for root stability. Plants are an open field. Generally foliage, not flowering, houseplants are used. Purchase them small, of course, wash or shake most of the soil off the roots and set them in with either your fingers or bamboo sticks. Insectivore plants like Venus fly traps, pitcher plants, hedera ivy, date seeds, citrus seeds, ferns, and creeping fig are all fun. Add some moss from outdoors, gathered from the north side of a tree or off some damp soil for interest. Drop in a stone or two, and voila, you have your terrarium made. Mist the planting with distilled water; cover the top with saran wrap; uncover if the interior fogs up, then recover. Keep in bright, indirect light. Under a fluorescent light is best; do not set it in a sunny window or you'll cook the plants! Any store or nursery that sells houseplants should be able to help with some of the details that I may have left out, but this should get your started in the right direction.

Q: I sent you a hibiscus leaf awhile ago and you said you didn't find anything on it. I am looking at a leaf and I see white webs and tiny insects that look black, but if I rub them they appear to leave a bloody streak. I've got some sweet potato slips going, and the insects like them better then the hibiscus, or at least they seem to thrive on the sweet potato. Any ideas? (E-mail reference, Gwinner, N.D)

A: Those are spider mites that are showing up on your plants. Control them with sprays of Insecticidal soap, making sure to get the undersides of the leaves and the leaf axils.

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