September 13, 2001

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: Enclosed is a sample of a weed that I’m trying to identify. Could you tell me what would kill this weed that is invading my grass? (Aberdeen, S.D.)

A: It looks like a member of the sunflower family ( Asteraceae) more specifically bur ragweed. This is a tough perennial that spreads via seed and rhizomes. But, like any other weed it is vulnerable to herbicides at this time of year. I suggest a good dose of Trimec with a surfactant before it sets seed.

Q: Everyone in town loves this tree when it is full bloom, but I haven’t found anyone who can name it. Also, where do I get trees started? We get little trees sprouting up all over, but the landlord won’t let them grow until fall, so we can’t transplant them when dormant. (Faulkton, S.D.)

A: The tree is a black locust. Local nurseries should carry them.

Q: I’m enclosing a sample of a weed or grass that has taken over our garden. I’ve never seed it this bad before. Please identify it and tell us what to do about it next year. (Orient, S.D.)

A: The grassy weed is large crabgrass, a flourishing annual in your part of the country. There are plenty of pre-emergent herbicides that can be applied next spring prior to planting that can control it.

Q: I am sending you some leaves from my plum tree. I would like to know what is on them. It is all over my tree. What do I do, spray or cut the tree down? (Mercer, N.D.)

A: Those are harmless galls; they are nothing to worry about. Spray the tree with dormant oil and lime sulfur next spring just before leaves open.

Q: Enclosed are pods that have formed on my miniature day lilies and stopped the blooming process we enjoy so much. What is the cause? Should I remove them? (Litchville, N.D.)

A: Flowers eventually form seed, and that’s what these pods are. You can remove or allow them to remain. No harm will come to the plants either way.

Q: What is causing my plum tree to drop its fruit prematurely? My pear tree isn’t dropping its fruit but only has four pears. Is there any fertilizer that I could give to the tree? Am I having problems with it because it is a semi-dwarf pear? I also had a problem with my beets this year. They didn’t produce any roots; what is lacking in my soil? The leaves on my grapes are turning yellow. Is it still safe to eat them? (Bonney Lake, Wash.)

A: Fruit drop can occur for several reasons: drought followed by a period of heavy rain or irrigation.; insect (plum curello) larvae feeding on developing fruit; colder than normal temperatures after a warm period; excessive wind or too heavy a fruit load for the tree to support.

Topdressing with barnyard manure is an acceptable way of supplying nutrients. The semi-dwarf nature of your tree has nothing to do with the problems you cite. Generally lack of development of bulbous roots like beets is an indication of low phosphorous levels. I suggest having your soil tested. It will be safe to eat your grapes provided the fruit itself is not infected.

Q: I am interested in growing chokecherries that are the same quality as the mother tree. Is that possible to do if I use fruit from the original tree? Also, can the chokecherry be crossed with something like a common pie cherry to produce a superior hybrid? (Turtle Lake, N.D.)

A: To get the same quality of fruit as that you sent me you’d have to equalize the genetics and the environment. To do that, don’t use the seed as you will get genetic variation; instead, use the branches for root cuttings. Yes, a cross is possible. They are both in the same genera, so they are closely related. Give both of your questions a try. Who knows? You might become famous and rich someday!

Q: I have two clumps of lythrum that I would like to divide. Would it be okay to do this in the fall or would spring be better? (Williston, N.D.)

A: Lythrum can tolerate either time. I prefer fall, as the root system has a chance to settle in before top growth begins.

Q: Enclosed is a vine that came into my flower bed and has spread all over. It is quite woody at the base and the berries go from green to red. What is it and is it something I should try to get rid of? Also, what can I use to get rid of bugs that eat almost everything in my flower bed. I tried Sevin, but it didn’t seem to work. I found cutworms in my hanging planters. I used only commercial dirt. Did they come in the dirt? (Jamestown, N.D.)

A: The vining plant you sent is nightshade, a member of the tomato family, hence the similarity in seed. Yes, get rid of it before the fruit drops and deposits seed. Try Orthene to control the insects. It is both a contact and systemic. That will take care of any feeding insects. The cutworms are the larval stage of night-flying moths. The adult thought your hanging baskets would make a nice home for her children.

Q: Can you tell me what kind of tree this is? It is about 15 feet tall, bushy, and grows in thickets. This year was a very good one for fruiting, but I haven’t tried using these fruits for anything yet. (Minot, N.D.)

A: Thanks for the good sample, which turns out to be a hawthorn, a member of the rose family. The fruits can be eaten, but they are not tasty. I would suggest leaving them for the wildlife.

Q: What should I use to get rid of quackgrass? Next, can you tell me how to crack black walnuts and get the meat out? Freezing was one step, but I can’t remember what the next one is. Also, how do I keep webworms from making webs in my ornamental crab trees? (Sioux Falls, S.D.)

A: Quackgrass can be controlled with Roundup or Poast. Roundup is non-selective, while Poast is a selective herbicide. This simply means that Roundup will kill anything green that receives its spray. Would the next step be to drop the black walnuts in hot water? That would cause a sudden expansion and possibly crack the shell. Otherwise, place them on concrete and get a hammer! Webworm control is most effective with a dormant oil spray next spring while the trees are still dormant. That takes care of the over-wintering egg masses.

Q: This weed is taking over my lawn! What is it and what can be done to get rid of it? It seems to lay flat and I cannot cut it short with mower. The second sample is another sample of a weed that is taking over another part of my lawn. It appears blue compared to the other grass. (Jamestown, N.D.)

A: The first weed is crabgrass, an annual that will be killed with the first hard frost of the fall. Control seed germination next spring with an application of a pre-emergent herbicide. See the NDSU publication Weed Control in ND Lawns, H-1009. The other weed looks like one of the bentgrasses. Spot spraying with Roundup will take it out.

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