February 8, 2001

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: Each spring I do a little pruning on my red maple at the lake. I understand that I can take an 8-inch cutting from a pruned branch, dip it in rooting hormone, secure it in an environment that will support the cutting, keep it moist and warm and mostly shaded for 45 to 60 days, and the cutting will take root in time for transplanting and establishment in the ground before fall freezing. If this is so, is there a certain technique to use, a certain "strength" of rooting hormone, a certain rooting medium to use, any certain care to take to propagate this beautiful tree? Any information would be appreciated, as I plan to propagate red maples in both Minnesota and North Dakota. (E-mail reference, Fargo, N.D. and Devils Lake, Minn.)

A: You are correct; red maple will root from cuttings and grow into beautiful trees. Here is what Dirr, the woody plant guru of North America, suggests: use only healthy, firm wooded stock, with mature leaves, that have either a single or multiple nodes, dipping them into a 5000 ppm (parts per million) IBA in 50% alcohol, 50/50 peat/perlite, apply mist evenly and without fail, and cuttings should root in three to five weeks. IBA is a synthetic rooting compound known as idolebutyric acid that stimulates the formation of adventitious roots, which is what you want to do. This is diluted in alcohol -- the rubbing kind, not the drinking -- and the stump ends are dipped into the solution prior to sticking into the rooting medium. The use of bottom heat always helps speed things along, so I would add that to his suggestions as well.

Q: During our gardening season last year, the majority of cabbages harvested were unusable due to dead leaves within the head. The heads looked beautiful on the outside but when cut were full of brown dead leaves within the healthy ones. (E-mail reference, Enderlin, N.D.)

A: Good question! This is known as black rot, a bacterial disease that is seed-borne. To avoid, plant only certified seed, or treat the seed by soaking in water at 122 degrees F. for 30 minutes. Rotate your plantings (follow cabbage with beans, corn, tomatoes, etc.), don't overcrowd the planting, and plant in well-drained soil. Of course, avoid overwatering as well. Often when you visit a farmer's market, they will have a cabbage head cut in half to show that the crop is a healthy one, and you will not get any nasty surprises.

Q: I was just wondering, do spider plants (the normal houseplant type) grow flowers? I just recently bought one, and I haven't dealt with them since grade school. I can't remember if they have flowers in spring or not. (E-mail reference)

A: Spider plants (Chlorophytum spp.) will produce small white flowers followed by tiny plantlets, which you can root easily anytime you want to start another new plant. It is usually not tied to spring specifically, but to being a little pot-bound as the plant ages.

Q: I'm doing a science fair project with spider plants. What environment does a spider plant grow best in? (E-mail reference, Halstad, Minn.)

A: This plant, properly known as Chlorophytum comosum, has been grown as a houseplant for over 200 years and will tolerate anything found in a normal house -- dappled sun, shade, hot or cool rooms, and it doesn't mind dry air. So what the best environment would be, I'm not sure, as I have seen them thrive under just about any conditions. My best guess would be either an eastern or western window, behind some curtains or blinds in a bedroom, bathroom, or kitchen.

Q: I have a grey fluffy mold growing on the topsoil of a few of my indoor houseplants. Will spraying lysol on the soil to kill this mold hurt my plants? (E-mail reference, Charleston, S.C.)

A: The mold is a saprophyte, which is a fungus that lives on decaying organic matter in your container. It posses no threat to your houseplant and usually responds to surface cultivation and air movement. I am not sure what effect Lysol would have on your houseplant, so I wouldn't take a chance. Simply scratch the surface and turn a fan on the plant, and allow the surface of the soil to dry between waterings. If this fails to work, simply scrape off the top layer of soil and replace with fresh, pasteurized material.

Q: We’re an eighth grade class at Platte Colony School and we’ve been studying plants in science. Our teacher brought a "Blackie" fig to school after having it outside all summer and it appeared very healthy. It now looks sick. It gets new, healthy-looking leaves, but when the leaves are full grown they get diseased looking, after which they shrivel up and die. We are enclosing a sample of the diseased leaf. Can you tell us what is wrong with this plant, and perhaps suggest a way we might treat it? (Platte, S.D.)

A: Your plant sample arrived in pretty poor condition. A lot of secondary decay had begun, so diagnosis was difficult. When sending plant leaf samples be sure to send them dry, in a zip-lock bag. I have no listing in my references for a "Blackie" fig. However, based on what you have told me and knowing what typical care is given houseplants, I suspect that the fig is being infected with one of the water molds, either Pythium or Phytophthora. These typically develop in containers that are poorly drained or where water is splashed on the foliage at the time of watering. I suggest repotting the plant in soil that is not as water-retentive in a container that is free-draining. Try to locate the plant in a bright but indirect light location, and increase the air circulation around the plant. Allow the soil surface to dry completely before watering again, and try hard to not splash the water on the foliage. I don't like to recommend pesticides for houseplants, especially when they involve young people like you.

Q: Enclosed is a sample from my coleus. Can you tell me what the fuzzy white clumps are and how to treat it? (Wimbledon, N.D.)

A: The plant has a bad dose of cottony-cushion scale. I suggest making up a solution of insecticidal soap, wrapping some aluminum foil over the top of the pot, and dipping the aerial part of the plant into it and swishing it around. That should take care of them!

Q: Do boxelder bugs need boxelder trees to survive? (E-mail reference, Mott, N.D.)

A: The boxelder bug, also known as Leptocoris trivittatus, is found where ever the boxelder tree (Acer negudo, also known as Manitoba maple) is grown, especially the pistillate (or female, seed-bearing) forms. They feed on the developing seeds, leaves, and tender twigs. They will also feed occasionally on other maples and ash trees. These attractive insects are known mostly for their nuisance qualities because of their habit of congregating in large numbers near or in homes as winter comes on, seeking out places to hibernate. They emerge the following spring as the weather warms, migrating to one of the host plants, with the boxelder maple being the preferred one. Certainly the landscape would be improved with the removal of the boxelder tree or trees and replacement with something else that is not a known host of this insect. Without a suitable host, their numbers would decrease to the point of non-annoyance.

Q: I have three quaking aspen trees in my front yard. I am having two separate problems with the trees. First, the trees send up suckers in the lawn each year. Is there any way to kill the suckers without killing the main trees? Second, for the past three years the trees have defoliated by early September. The leaves will start to develop lesions around July 1 and then turn black before falling off in September. What could be causing this problem? (E-mail reference)

A: Unfortunately, there is little you can do about the suckers coming up from the quaking aspen in your yard. I have two in my back yard, nestled amongst a wildflower planting, and I have to go in a couple of times a year and prune out some vigorous suckers. This just happens to be a characteristic of the tree. While spraying the suckers with a broad-leafed herbicide would kill them back, it may also weaken and eventually kill the trees. I do not recommend this action.

The early defoliation could be caused by a fungus called Marssonina leaf spot. Unfortunately, there is no registered fungicide for controlling this disease. The best procedure is to rake up all fallen leaves in the fall, prune out all dead and cankered twigs and branches in the late winter or early spring, and spray with a lime-sulfur just before bud-break. This acts as a surface sanitizer, possibly controlling any further development of this disease. Then, sometime before the first of July, I'd suggest spraying the trees with a fungicide containing chlorothalonil (Daconil, Ortho Multipurpose Fungicide). This should help control the disease and keep the leaves on the tree for their normal span of time.

Q: I have access to worm castings from a worm farmer. Could they be mixed with the starter mix I use in my greenhouse or would it be too rich? The county agent said disease could also be a problem. Would it be best if I waited and used it in the transplant soil mix? (E-mail reference, Minot, N.D.)

A: Worm castings would be best used in the transplant mix. Your plants should take off beautifully after that.

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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.

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