NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
September 2, 1999
Ron Smith, Extension Horticulturist
North Dakota State University
Q: My ficus has been healthy until recently. Now the leaves are turning yellow and dropping off. Please help me save my tree! (White Lake, S.D.)
A: It is hard to know what is specifically wrong with your tree, but I can give you some ideas. One possibility is that you have root damage caused by insects such as mealybugs. You can apply a granular systemic insecticide or Orthene, a liquid systemic insecticide.
It could also be that the plant has been moved. Sometimes ficus trees can be sensitive to variations in light conditions and lose leaves easily if stressed by light, water or drafts. It can usually be acclimated to environmental changes within a few months.
Q: Can you tell me what is wrong with my rudbeckia leaves? The plant blooms beautifully. Only the leaves are affected. (Platte, S.D.)
A: The leaf decay on your rudbeckia is caused by a blight or gray mold (Botrytis sp.). Clean up all leaf litter to allow proper aeration of the soil near the base of the flowers. Either disease spreads easily in damp conditions. Furthermore, sprays can be applied in the spring as a preventive measure. Examples are Captan, thiram, benomyl or maneb.
Q: We have two Wisconsin balmer peach trees that are about 2 years old. Some of the leaves have brown spots on them and are drying up. What causes this? Is there something we can do about it so the trees won't die? (Aberdeen, S.D.)
A: I can give you some general possibilities: bacterial leaf spots, leaf blight, rust or leaf spotting caused by a pathogen such as Septoria flagellifera. I suggest you send a sample in to your local extension agent and have him or her give you advice on respective pesticides.
Q: I have a plant that I call Snow-on-the-Mountain, but my Ortho book says it's Euphorbia. I am wondering what the correct name is, and what is wrong with it. It looks like fungus to me. I also would like to know if you have any plans to offer the Master Gardener program in the Maddock area? (Maddock, N.D.)
A: Your plant is variegated bishop's weed, and it appears to have rust. Just cut it off or even mow it back, clean up the litter, and it will send up vigorous new shoots.
The Master Gardener program will begin in January 2000, but we haven't determined the sites in the state yet.
Q: Please advise me on what I can use on Creeping Charlie. I am losing ground pulling it! Also, I have fungus on my Canadian chokecherry tree, and it has sucker growth around the base. Can these problems be controlled with chemicals and not damage the tree? (Enderlin, N.D.)
A: Creeping Charlie, or ground ivy, can be spot sprayed with Trimec herbicide, if it's a weed in your lawn.
There isn't any way to stop a Canada Red chokecherry from suckering without killing the tree, but you can spray fungicide to control the fungus. A general all-purpose fungicide is Daconil 2787. It is most effectively sprayed in early spring as a preventive measure.
Q: I have cosmos that look beautiful, then suddenly wilt and die. Out of four plants I only have one left. Any ideas why? I am also wondering when and how to divide switch grass. Finally, can you tell me what the difference is between lilies and daylilies? (Hoven, S.D.)
A: The cosmos are probably infected with Verticillium wilt. It's a pathogen in the soil and very hard to control.
You can divide the switch grass best in the early spring when it is dormant.
Lilies grow from bulbs whereas daylilies grow from tubers. The flowers are somewhat similar in appearance (though lily petals are more slender), but the plants are definitely not! Daylily plants look similar to clumps of overgrown large-leaf grasses while lilies look like your typical Easter lily plant, with a central stalk and slender leaves spiraling from it. The different types of lilies are named so because of their various plant characteristics--plant height, flower color, hardiness etc.
You can order lilies and daylilies from most any mail order flower/bulb catalogs, or maybe put in a request to a gardening friend with extra plants. Lily bulbs should be planted in the fall. Daylily tubers can be planted then or in the spring, and the plants can be divided and replanted almost anytime during the growing season.
Q: I discovered a plant growing in one of my flower pots. It gets buds with yellow showing, but they never open. What is it? (Wishek, N.D.)
A: Your plant is known as velvetleaf, a weed that belongs to the Mallow family. The seed is viable for a long time, so keep it from producing any. The plant is a warm weather species and can get to more than 6 feet tall!
Q: I read in a magazine that there are three easy ways to start new plants from a clematis, but I lost the article. Could you please tell me how to start new ones from my original plant? Also, what is the best way to prepare it for winter? Should I cut it back or leave the vines on the trellis? (Tower City, N.D.)
A: Clematis can be propagated by softwood cuttings taken in the spring under mist in about five to six weeks. Semi-hardwood cuttings taken in late spring to late summer (now!) work better. You likely have the jackman clematis, which blooms on new growth each spring. The usual suggestion is to cut it back to about 12 inches above the soil line at that time. Many folks will do that operation in the fall before the snow flies, then mulch heavily. Either way seems to work out.
Q: Every year about Oct. 10 I fertilize all the trees in my front and back yards. Then I put my soaker hose on and water them thoroughly. I can't afford to water my whole lawn, but I would like to keep my trees. I've been told that the root system on these trees is so far down that I am wasting my time. Is this true? (Ipswich, S.D.)
A: Someone doesn't know what they are talking about! The root system of a tree does not go beyond its capacity to absorb air and water. Most of the feeder roots--that is, those which take in the nutrients and water are within the top 12 inches of the soil. Continue what you are doing! The trees are obviously benefitting from it!
Q: Can you tell me what is wrong with my chokecherries? It looks like fireblight, but I didn't think it attacked Prunus varieties. (Wolf Point, Mont.)
A: I agree that it is fireblight bacteria taking out your chokecherries! I must admit this is the first time I have seen this disease hit chokecherries. Try to control it in early spring with bordeaux mixture when the temps are hovering in the 60s. Start at blossom time. As the weather gets hotter, change over the Streptomycin. To get a jump on next year, spray the trees with dormant oil combined with lime-sulfur, just prior to the blooms opening or leaf-out.
Q: Do I need to dig up iris bulbs in the winter? (Napoleon, N.D.)
A: Actually, irises grow from rhizomes--underground stems. More than likely, you shouldn't have to dig them up, as most are hardy in our region.
Q: I have a problem with blight in my garden, on the tomatoes and potatoes. Is there anything I can do to get it out of the soil? I've been told to cover the garden with clear plastic and the sun will destroy it. Is this true? (Detroit Lakes, Minn.)
A: Oh, if only it were that easy! The best thing you can do are all of the following:
- Be fanatical about cleaning up the garden debris this fall.
- Rotate the crops--have beans, corn, carrots, or cabbage follow your tomatoes and potatoes.
- Select resistant cultivars.
- Employ drip irrigation, or at least avoid watering overhead.
- Monitor regularly for diseases getting started. At first symptoms, apply a multipurpose fungicide.
Q: As the chill fills the air, it reminds me that soon I will have to move my house plants back inside. Any tips you can pass on to me in preparing my plants for indoors? (Carrington, N.D., e-mail)
A: I would suggest repotting with fresh potting soil, in completely cleaned up containers or pots (or new ones if necessary). Hosing the plants off with a spray of water and following up with some insecticidal soap usually does the trick as well. In situations where my house plants have obviously had the attention of some leaf munchers, I isolate them in a plastic bag with a no-pest strip overnight. That procedure usually works quite well for us.
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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: Dean Hulse (701) 231-6136