February 1, 2001

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I have the weed speedwell in my lawn. What can I use to get rid of it? It has taken over a part of the country cemetery also. (E-mail reference, Forman, N.D.)

A: All the speedwells I know in this part of the country are annuals, so a pre-emergent that will control broadleaf annuals should do the job. If the pre-emergence opportunity is missed, then Trimec should take it out. Try to get the weed in the early stages of growth when it is most vulnerable to herbicides.

Q: I want to take out a row of Caraganas around my home. Any suggestions on how to best do this? (E-mail reference, Carson, N.D.)

A: I assume that they are old and large, so the task will not be easy. I suggest cutting them back severely, and when new growth emerges, spray them with Roundup to get a good kill on the roots, being sure to mix the Roundup with ammonium sulfate for greater effectiveness. Then, with the stumps that remain, you can either rent a stump grinder and grind them down below the soil surface, or, if that isn't work enough, they can be chain pulled out with a truck or winch.

Q: I had a patron stop in today who starts her tomato plants from seed. Her question is, what are some of the best varieties of tomatoes to grow in this area? (E-mail reference, Valley City, N.D.)

A: There are probably close to 100 varieties of tomatoes that can be grown in North Dakota.

Celebrity is one of the best hybrids as it grows with few problems and produces good sized (not jumbo) fruits. Others are: Sweet 100, Sweet Million, Better Boy Hybrid, Burpee Hybrid, Early Girl, Stupice, Siberia, and Better Bush Hybrid to name just a very few. Some are bush, some are indeterminate; some are large and some are small, depending on what the gardener wants.

Good sources for the seeds are:

Totally Tomatoes
Catalog Fulfillment Center
335 S. High Street
Randolph, WI 53956

Tomato Growers Supply Co.
P.O. Box 2237
Fort Myers, FL 33902

Q: Would you please tell me how you put a shamrock to rest, how long it should be in a rest period, and do you cut it down? (E-mail reference, Ayr, N.D.)

A: I'm afraid that you've got me on this question. I know they need some rest, but how much, I don't know. Usually six to eight weeks is a sufficient rest period for many plants, and generally they are allowed to dry down. I will stand corrected by anyone who will come up with more concrete information than this.

Q. My 4-year-old apricot tree got lots of flowers in the spring but no fruit at all. Do I need to plant another apricot tree to pollinate? What should I do? I read an article in a magazine with pictures about apples that are trained and kept short in the front yard but still bear a lot of fruit. The thing is, they did not include how to train and prune them. Can you give me some tips how they did it? (E-mail reference, Milpitas, Cal.)

A: First of all, thanks for identifying who you are and where you are writing from. It helps me to focus on the problem a little better and gives me a person to respond to instead of just a message. I wish everybody did that! About your apricot tree. While it is not clear whether or not apricots need another to cross-pollinate, it would be a good measure of security to have another one for that purpose. Even if not necessary, it will only make the fruit set better. I don't know your climatic conditions in that part of California. In our part of the country, the apricot is usually prevented from setting fruit by spring frosts damaging the blooms. That could be the case in your territory as well. The fact that you are getting flowers is encouraging; you could be lacking in bee activity at the time the blooms are open, it could be too windy, or too rainy. For now, try the additional tree. California produces 95 percent of the apricots sold in the U.S., so somewhere in the state things are going right! What you likely read was about the art of espalier -- a technique that has fruit trees pruned in a geometric form, generally in two dimensions -- vertically and horizontally -- against a wall or fence. Book stores or a local library should have information on that. If that isn't it, then they were creating topiary plants that have unique shapes. Again, local references should help.

Q: I have a number of African violet leaves started and it looks like a number of plants coming on each leaf. It is best to trim out all but one, or let them all grow? I have had an Annabelle hydrangea for about eight years, but it has not blossomed. The last few years a few have started to form, but do not continue to mature. I tried putting on miracid, but it did not help. At the garden center they suggested a soil acidifier. I tried that last year, but that did not seem to help either. Do you have any suggestions or know what the problem could be? (E-mail reference, Bruce, S.D.)

A: I suggest letting the African violets grow for awhile. Once the original leaf has died off and the plantlets have matured somewhat, you can divide the crown into two, three or four plants.

Generally, the lack of flowering is due to either too much nitrogen or not enough sunlight. If you are too good to the plant nutrient-wise, it may just simply grow vegetatively and not produce flowers. I suggest giving it some "traumatic stimulation" early this spring, by taking a straight-edge spade and pushing it into the ground in about three places outside the spread of the plant to sever some of the roots. Do this before leaf-out takes place. This often pushes a reluctant shrub or tree into flowering within a season.

Q: Do I really need to put fertilizer on my trees? If so, which one do you recommend? (E-mail reference, Milpitas, Cal.)

A: Fertilization of trees is suggested only in response to a deficiency. Generally, trees need little additional nutrients, since they have an extensive root system to mine ample nutrients from the soil. If you start to notice chlorosis (yellowing of the foliage) or shortened internodes on the branches, then it might be advisable to add a complete fertilizer like a 10-10-10 or one that contains microelements like iron and copper. To know where your soil stands in nutrient content, I suggest getting a soil test done. Have the pH, organic matter, N,P, and K and the soluble salts checked.

Q: We have a grandson who wants to use plants for his science fair. I have two geraniums; one has had natural light and is straggly, the other 16 hours of artificial light and is robust and beautiful. Can you give me some suggestions as to how he can present the plants? Where would we find a light meter? I went on line searching but came up with photography equipment. Any clue as to what we would expect to pay for one? (Gwinner, N.D.)

A: Using a light meter would give some concrete data that he can make reference to, like the robust plant receives 16 hours of light at a footcandle reading of 1000 FC while the spindly plant receives only diffused light, which varies between 50 to 150 FC per day. You can contact Hummert International, located in Earth City, MO. Their phone number is 1-800-325-3055. They have a duo plant light and water meter for about $20. The model number in their 2000 catalog is ID-1830, catalog # 65-6802. While not a "professional" model, it should certainly be enough to provide your grandson with the information and data that he needs for his project.

Q: A lady called me today and said she attended the juneberry session at Marketplace in Bismarck. During the session it was brought up that you should not plant spruce by juneberries. Why would that be? I know of the problems with junipers and apples, but have not heard of the spruce and juneberry dilemma. (E-mail reference, Minot, N.D.)

A: Your client is confused or mistaken. There is no problem with juneberries and spruce that I am aware of. There is cedar-apple rust where the alternate hosts are juneberries and junipers, but not spruce.

Q: Last year I planted "Straight Eight" cucumbers in my back yard garden. The cucumbers were bitter. I watered evenly and consistently with the exception of one week that I was away and we did not receive any rain that week. Could there be some type of deficiency in the soil? Should I just try a different type of cucumber? (E-mail reference, Casselton, N.D.)

A: I am sorry to report that it was the dry week that caused the bitterness. Cucumbers need 1 inch of water per week -- every week -- and any water stress results in the fruits being bitter. Straight Eight is a good variety, as I have planted it many time with good success. I would encourage you sticking with that until something else catches your fancy.

Q: This coming spring I need to replace four American elm trees in our yard. What do you recommend as replacement trees? (Rogers, N.D.)

A: I recommend polyculture rather than one species of tree. For example, you could plant an Amur or Tatarion maple in your front yard, a Japanese tree lilac or serviceberry in the back, and either laurel willows, Manchurian ash or Ohio buckeye along the street.

Q: I am thinking about getting into commercial pumpkins. What are weed control options for grassy weeds and broadleaves, specifically kochia and milkweed. (E-mail reference, Linton, N.D.)

A: Roundup is labeled for pumpkins, but of course the spray must be directed away from any pumpkin plants. This (actually Roundup Ultra) is applied up to three days before seeding or transplanting. Dacthal is another one that can control some broadleaf and grassy weeds, and it must be applied to weed-free soil. Finally, there is good-old Poast which is the ultimate grassy (emerged) weed control. In every instance, you are responsible for following the directions and adhering to the information contained on the label.

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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