NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
July 27, 2000
Ron Smith, Extension Horticulturist
North Dakota State University
Q: I've written to you in the past about pH problems in my soil and water. You've said there was no practical way to treat the water. However, I am being given a 500 gallon water tank and propose to pump the creek water into it and treat it to make it usable for gardening purposes. My idea is to use muriatic acid, which I now use to initially get the pH down in our hot tub. But I have some questions about the safety of using that. Do you know or can you refer me to someone who would be able to answer some questions? (Washburn, N.D., e-mail)
A: Muriatic acid is usually sold as a salt of hydrochloric acid, in the form of potassium chloride and is used as you intend--as a fertilizer. The same material that is used in your hot tub to lower the pH would be too strong to use on plant material, unless greatly diluted.
I would suggest using sulfur-containing fertilizers. Mix in powdered sulfur and sphagnum peat moss into the soil. All of this is a lot safer and more permanent.
Q: I have a trumpeter vine or butterfly vine. It grows slowly and I can not get it to blossom. It is 3 years old. What am I doing wrong with it? Also, I have not repotted my Christmas cactus for five years, and I am wondering if it is time. (Morris, Minn., e-mail)
A: I suspect you are being too good to your vine. Try root pruning it a little to stimulate flower production. Simply drive a straight-edge spade into the soil a few feet away from the vine to sever some of the roots. Avoid fertilizing at all. If it still fails to flower next year, then it is likely in too shady a location.
Concerning your question on the Christmas cactus, if it has been five years since the last repotting, I would say that repotting it in the next nominal-size container would be a good idea. Summer it outdoors--not in direct sunlight--and it should produce an abundance of blooms for you this winter.
Q: I have an apricot tree that is dropping fruit with insect larvae emerging from the inside. The leaves on the tree have shot holing in them and skeletonizing. Do you have any tips for me? (Ellendale, N.D., e-mail)
A: Sounds like you have two distinct insects zeroing in on the poor apricot tree! Leaf skeletonizing is typically caused by a sawfly larvae. These are ugly-looking, slug-type larvae that chew the tissue between the veins of the leaves. If their presence is no longer noted, then spraying is not recommended. If they are still active, then spray with either pyrethrin, roteonone (organic), malathion or Sevin (non-organic).
The second insect is the plum curculio. About the only thing you can do right now is to pick up dropped fruit and destroy it. Sprays now would do little good. This fall, follow good sanitation by removing all fruit that has dropped. Next spring, spray after petal drop and the fruit has set with any of the pesticides I’ve listed.
Q: We are having problems with our young silver maple trees. We trimmed the 3-year-olds last year because they were growing branches all over. We cut off the lower branches to make the trees grow straight, not crooked. This year, neither the 2-year-olds nor the 3-year-olds have any leaves on them, and they are growing shoots out of the bottom. We also planted some green ash trees at the same times and they look fine. Do you have any suggestions as to what is wrong or is this normal? (Wessington, S.D., e-mail)
A: It sounds like you got ahold of a seedling selection that did not originate from your geographical region. Seedlings coming from regions of the country south of your location may not survive the winters or those trees might be teased into or out of early dormancy or early bud break by a different day length. I suggest cutting or digging out the roots that are now suckering on you. Sorry for the bad news!
Q: We transplanted some wild grapes by the garage and are encouraging them to grow up the wall onto an arbor. They are about 6 years old and doing quite well, except for this twofold problem: First, the vines will fill with small grape clusters in the spring but will eventually all die off so there is no fruit in the fall. What could be causing this?
The second problem may hold a key. The vines are just full of small gnat-like insects that fly all around a person when you are close to the vines. How do I get rid of these bugs, and are they detrimental to the vines? (Adrian, N.D., e-mail)
A: I would use a pyrethrin spray. It has good knock-down power and very low mammalian toxicity. Be sure there are no pollinators active at the time. Early morning or afternoon is usually the best time to carry this out. A couple of applications may be necessary to bring them under control.
As to what the insects are, I can't say for sure. Grape vines attract a good selection of pests, from mosquitos to fruit flies, and many things in between.
Q: Could you please tell me how to start a new weigela from a clipping? I have two: one 5 feet tall and the other 3 feet. I would love to start one, but I’m not sure how to do it. (Spalding, Mich., e-mail)
A: This attractive shrub is easily propagated either by hardwood cuttings planted in the early spring or by softwood tip cuttings under mist taken any time from spring into fall. Treatment with IBA, a rooting hormone, would accelerate the process.
Q: I have a big 35- to 38-foot-high very bluish-green pine tree that has some grass growing very close to it. It looks like quackgrass. I have tried spraying it with something I use for dandelions, but it doesn’t seem to be helping. (Eureka, S.D.)
A: Quackgrass will not be affected by herbicides that control dandelions. Using Roundup at the base of your pine tree will not hurt it, and the Roundup should control your quackgrass.
Q: I have a beautiful bed of lily of the valley on the north side of my house, but it never blooms. Why? (Medina, N.D.)
A: The only reason I can think of why your lily of the valley won’t bloom is because you’re being too good to the plants. It’s likely they are getting too much nitrogen, which results in keeping the plants in a vegetative state. Nitrogen could be reaching the lilies when you are fertilizing the lawn. Try to keep the spreader away from the lily bed by at least 2 feet.
Q: I think there is quackgrass growing in my lawn, but it seems much finer than regular quackgrass. Could you please let us know what kind of grass it is? (Campbell, Minn.)
A: I can tell you for certain that it is not quackgrass. My best guess is that it could be either Sandburg or Canada bluegrass.
Q: We have a cutleaf birch which is about 11 years old. The problem is that we have woodpeckers that have been putting holes in our tree, and we are afraid that they will kill our tree with all the holes. What can we spray on the tree or what can we do to deter these birds from pecking on our tree? (Oslo, Minn.)
A: I too have a cutleaf weeping birch that the woodpeckers did some work on, and it is still going strong after 15 years! If you can catch them in the act, spray the birds with a garden hose. Hang aluminum pie tins. Or apply tangle foot to the area, and wrap it in aluminum foil. Those are all the tricks I know of to discourage them. Woodpeckers often move on before their damage becomes extensive. It is illegal to shoot these birds.
Q: How do I get rid of volunteer violets in my yard? (Clear Lake, S.D.)
A: Give Trimec a try, around Labor Day weekend.
Q: I have been noticing that most of the chemicals for white grub control list halofenozide as the main ingredient and say it can be used anywhere. Is it really that safe? (Crookston, Minn.)
A: Halofenozide is a new class of insecticides known as an insect growth regulator (IGR). The chemical’s function is to interfere with the normal molting process of the target insect. It is considered safe to fish, birds and animals when used at label rates.
Another one to consider is Dipel (or Bt), a biological material that kills by gradually making the grubs sick. Then they stop feeding and die. It is also very safe.
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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