NEWS for North Dakotans
Agriculture Communication, North Dakota State
University
7 Morrill Hall, Fargo, ND 58105-5665
July 16, 1998
Ron Smith, Extension Horticulturist
North Dakota State University
Q: I'm wondering why my amaryllis chose not to bloom this year. (Mitchell, S.D.)
A: The amaryllis will bloom when it has accumulated enough energy to do so. Be patient. Let it stay in leaf through the summer, then get it into dormancy this fall. It should bloom for you after that.
Q: Enclosed are some leaves off a Radiant crab tree I planted about a year ago. I did not have this `blight' on it last year, and now it seems to be spreading to other trees. Help! (New Rockford, N.D.)
A: Your apple tree has a good dose of apple scab. Spray with Captan to prevent further spread of this fungus.
This fall, be sure to clean up all fallen leaves and apples. Next spring as leaves open spray again with Captan.
Q: I found this powder substance in ice cream pails in a neighbor's garage. They said they thought it was for use on evergreen trees, but I'm not sure. (Leonard, N.D.)
A: The material appears to be a water-soluble fertilizer like Miracle-Gro. You can dissolve 1 teaspoon in 1 gallon of water to apply to plants. Evergreens generally don't need fertilization, so be careful to not overdo.
Q: Can you tell me what is causing the enclosed apple tree to slowly die? It bloomed and produced very well until about three years ago, then it slowly began to look ragged. Also, why don't my mock orange trees bloom? (Hope, N.D.)
A: From the visual symptoms on the sample you sent, I'd say the tree is going through zinc deficiency. This is characterized by a general chlorosis, undersized leaves and short internodes.
I suggest an application of micro nutrients (Miracid) to help the tree along. Apply once a month during the growing season — May, June, July and August.
As to the reasons why your mock orange shrub will not bloom:
1. Flowering branches pruned out previous season.
2. Too much nitrogen from lawn fertilization.
3. Too much shade.
4. It isn't a mock orange.
Q: I planted Juneberry plants last year and they were growing fine, but now they seem to be an attractive food source for some insects that look like a small fly. They strip the leaves off and now are spreading to my cherry bushes. Can you tell me how to get rid of these insects? (Hankinson, N.D.)
A: It sounds like you have a couple of villains working on your Juneberry plants.
I cannot get a clear ID on the insect that is causing you the problem, based on what you have told me. It could be the winged generation of the wooly elm aphid, the Juneberry sawfly, the cherry shoot borer, or a combination of all three.
The leaf sample appeared to have the symptoms of anthracnose and a touch of a leaf spot fungus.
Based on this information and with a continuing contributing weather pattern, I suggest that you surrender. It appears you are fighting an uphill battle. Sorry.
Q: I have some questions regarding my fern-leaf or memorial peony. It is growing on the east side of my house, it comes up full and lush every spring, buds out, but when the flowers are in full bloom they are edged in black and rather misshapen. Should I move the plant? When should it be moved? Should it be cut way down? (Cooperstown, N.D.)
A: Peonies are not hard to grow — just particular about a few details about how they are grown.
It sounds as if your peony is being touched by a little botrytis. While they will grow just about in any soil in full sun, they will do better if the site is well drained. Fertilize them in the fall with a generous application of Milorganite or something similar.
I'd suggest digging and dividing in September. Be sure each division has three to five buds or "eyes." Throw in a handful of bonemeal or superphosphate, and set the divisions so that the tip of the lowest eye in no more than 2 inches below the surrounding soil level. Water in well, and mulch this first season to prevent heaving.
I suggest removing the foliage each fall when it has been blackened by frosts. The 1st to 10th of October is a good time frame to do this.
Q: I am enclosing leaves from a flowering crab tree. It seems to be sick. (Wimbledon, N.D.)
A: Your crabapple has a very bad case of apple scab (Venturia inaequalis). It is turning out to be a very prolific disease this year due to our wet weather.
Spray the tree immediately with Captan. Then, most importantly, clean up all fallen leaf litter this autumn—or in early spring before seasonal leaf-out occurs. I would also recommend a spray with lime-sulfur at that time, before leaf opening.
Once the leaves open, begin a vigorous program of preventative sprays with Captan or Captan plus benomyl. Continue every 10 days as long as the weather is conducive to disease development.
Q: I am enclosing some leaves from a tree that seems to be trying to start to come up all over the yard. What kind of tree is it? (Velva, N.D.)
A: Those volunteers you are digging up are boxelder maples (Acer negundo). They will likely reach a height of 20 feet or more in two decades, eventually topping out at 50 to 60 feet. They are considered fast growers, and are extremely durable in North Dakota conditions, hence their use in windbreaks.
A lot of criticism is directed toward this tree species, condeming it as a "weedy" tree (all those seedlings). I have seen some very attractive ones in my day. And what the heck, they are a prairie source for maple syrup!
Q: Enclosed is a too-friendly plant in our lawn. What is it and how do we get rid of it? Also, my fern peony buds but only one blooms. It's as if they dry up on the bud, even though I try to keep them watered and fertilized. How come? (Voltaire, N.D.)
A: Your "too-friendly plant" is a very determined weed known as ground ivy (Glecoura hederacea). It is a perennial that spreads by rooting on creeping stems, and reproduces by seed. This particular weed will thrive in shade, often out-competing the grasses that are attempting to grow in the same location. I once saw this weed so thick that I recommended the homeowner kill off the little bit of grass in it, and accept the weed as an alternative groundcover. Repeat applications of Trimec (or similar product containing dicamba) will kill it off.
Concerning your peony, try pulling about 1 inch of soil back from the crown of the plant and back off on overhead watering. Also, remove foliage in late fall once it has been blackened by frosts.
Q: I would like to know what I can spray on my strawberry plants, rhubarb, and iris bed to help control quack grass. I can't move it to another location because it is everywhere. Once I read an article you wrote about Poast or something like it. (Monsfield, S.D.)
A: You remembered correctly—it is Poast (sethoxydim). You apply it to actively growing grasses, but you cannot apply it within 7 days of harvest. For other information, refer to the label.
Q: Can you tell me what kind of plant I have enclosed here? It is growing in one of our flowerbeds. (Fargo, N.D.)
A: Your plant is horseweed, Conyza canadensis. It is an annual reproducing by seed.
P.S. Get rid of it! It is toxic to horses and humans are allergic to it!
Q: My sister in Spearfish, S.D., has this tree in her front yard and no one can tell us what kind of tree it is. It is huge with these beautiful big leaves. (Bison, S.D.)
A: The sample was in excellent shape, thank you!
The tree is American linden or basswood (Tilia americana). They do get quite large, and are quite durable for our prairie region of the country.
There are several cultivars which this tree may be one of:
- Dakota, a round headed form introduced by Ben Gilbertson from South Dakota.
- Redmond, perhaps one of the most handsome street or lawn trees in the United States, with a dense, pyramidal shape.
- Rosebill, an improved, faster growing selection that develops an open crown.
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Source: Ron Smith (701) 231-8161
Editor: Barry Brissman (701) 231-7866