Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: How can we get amaryllis bulbs to grow larger instead of multiplying? We already have 40 and don't need any more. (E-mail reference)

A: Good question. I think size is a matter of hybridization more than anything else. I suggest picking a couple of your largest 40, grow them to flowering, cross one with the other, collect the seeds, sow again, and repeat the process until you are satisfied with the size. Now you know why hybrids cost more!

Q: I have a beautiful silver poplar in our yard. Last fall, there started to be knobs popping up in the yard. I am trying to chop them out and replant grass. Please let me know of any suggestions on what to do about this. (E-mail reference, S.D.)

A: I am afraid that you have a tree that is prone to producing those "root knees" in lawns. The silver or white poplar (Populus alba) is one of nature's toughest trees, able to grow under some of the most impossible conditions I have ever seen. But, along with that toughness come some characteristics that cause it to lose favor with the owners, and those surface roots are one of them.

So, other than chopping them out like you have, I cannot make any other suggestions for you.

Q: When a mulch of bark is placed around a tree in the lawn area, what is the best substance to use next to the ground to keep weeds from growing through the bark? Is it better to use a landscape mesh to allow the moisture and air to pass through, or a layer of regular black or clear polyethylene with a layer of small rock to hold the plastic in place and the bark mulch on top of that ? I cleared the garden of plant debris and had the plot tilled this fall. Weeds have always been a problem , especially mallow, pigeon grass crabgrass. A crabgrass control product works well on the lawn. Can this same product be used in the portion of the garden where started plants like tomatoes are set out, and is it O.K. to use where large seeds like beans and corn are to be planted ? I have found that mallow is a difficult weed to control. I have heard it called "sheep geranium." Is it one weed that sheep will not eat? (E-mail reference, Faulkton, S.D.)

A: The mesh is definitely better! It allows air and moisture to move into and out of the root zone, encouraging the deep development of roots. Plastic creates anaerobic conditions that is unhealthy to the root system. All I can tell you is to read the label when it comes to pesticides; it is the law. If a product label does not list the crop, then it cannot be used legally. For example Treflan 4E and Prowl 3.3E are listed for emerging grassy weed control in most, but not all, vegetable crops. Products called Poast 1.5E and Select 2E can be used in controlling emerged grasses in tomatoes. Millions of dollars go into label development, so they end up being the best source of information for all of us.

Q: I have Nanking cherry bushes that are 3 years old and 5 to 6 feet tall. I don't want them any taller. Can I trim them as a hedge, and when would be the best time to do so? Also, how might I keep lambsquarter and kochia out of the strawberries? I have a huge patch and can't get it all pulled. (E-mail reference, Aberdeen, S.D.)

A: Yes, the Nanking cherry can be pruned as a hedge. It tends to open and spreading in the natural state, so the pruning would likely help to thicken the growth somewhat. Best time is in the early spring before leafout. To control broadleaves in stawberries, I suggest looking into Dacthal, Devrinol, or Princep.

Q: My Jade plant has grown extremely well in the kitchen window. My problem is that one side has grown more than the other even though I turn the plant. I would like to trim the larger side as the plant will fall over pot and all if not supported. How do I do this without causing harm to the plant? (E-mail reference)

A: No problem at all with pruning the jade plant - likely the Crassula argentea. Simply prune it as you would any shrub that has started to go out of bounds. Use a sharp, clean pruner and cut back to a lateral branch or one of the main stems. Don't be concerned with any sap flow. Allow your prunings to "cure" overnight and use them to propagate new jades.

Q: I planted around two hundred grape hyacinth bulbs the fall of ‘99 and they were beautiful this spring. But this fall they grew up about 5 inches. Will this keep them from blooming in the spring? Some of my perennials also came up with the nice fall we had. I hope they will be fine come spring time. (E-mail reference, Minot, N.D.)

A: The grape hyacinths and other perennials that are coming up are vulnerable to our upcoming winter weather. There is nothing you can do at this point except let nature take its course. Those that bloomed will likely not bloom next spring, unless our winter is unbelievably mild with little to no snow cover. Those that were just vegetative now may bloom next spring. I suggest mulching with straw or Remay (a geotextile product) to provide some protection. Other than that, all we can do is hope for the best next spring!

Q: My spruce tree is diseased. After reading NDSU Extension Service pamphlet PP-789, "Diseases and Related Problems of Evergreens," I believe it has Rhozosphaera needle cast, as the symptoms match including the presence of pycnidia on the needles. The pamphlet says that the disease "can be controlled by two properly timed applications of fungicide in each of two consecutive years" and "fungicide sprays may help but timing is critical." My question is, which fungicide and what are the proper/critical times to apply it? Also, should the dead branches be removed (some of the affected branches are totally dead; others are missing needles from the trunk out to the last foot or two from the tips)? The tree is 30-35 feet tall with the diameter of the lowest branches about 12-15 feet. The tree is partially covered on the diseased side by the uppermost branches of an much taller ash tree about 20-25 feet away (possibly the cause of the problem). (E-mail reference, Hatton, N.D.)

A: Our circular needs to be updated a little. The ID information is correct, we just need to put in what the current treatments are. The chemical to use is one called Bravo (chlorothalonil) mixed with Bordeaux mixture, making applications in early June and again in early July. Do this each year, until the progress of the disease is evident. Spray any other spruce trees on your property at the same time to give them protection. Remove any branches that have been heavily damaged by the disease. They are not going to releaf for you.

Q: Is it possible to grow blackberries in the Red River Valley? And if so, which varieties work the best? (E-mail reference, Grand Forks, N.D.)

A: As much as I would like to, it’s not possible, at least not yet. If our globe continues to warm with milder winters for us, they just might in future. But for now, I have to say no, they won't make it. Raspberries can produce in our area, so you might consider those instead.

Q: I have a beautiful jade plant that is apparently suffering from powdery mildew, which I understand is rare in living room jade plants. How can I eliminate it? Is there a spray on the market to treat this? (E-mail reference)

A: Rare indeed. Remove any badly mildewed leaves and lightly dust the rest of the plant with powdered sulfur. Set up a fan, or do something to improve ventilation around the plant. It should be no problem once the furnaces start to run for the winter, drying the interior air.

Q: I need some info on what is good grass to plant on grass greens. The LaMoure Country Club is looking to replace its sand greens with grass. (E-mail reference, LaMoure, N.D.)

A: Penncross creeping bent is the only way to go. However, grass greens require special attention, Like a nine- or 11-bladed reel mower, mowed every day in a different direction; a mechanic to keep the mower tuned and sharpened; an irrigation system that can syringe the greens when the temperature starts to climb; a fertilization and pest control program that needs spoon feeding.

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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) 8161, ronsmith@ndsuext.nodak.edu
Editor: Gary Moran, (701) 231-7865, gmoran@ndsuext.nodak.com