NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
July 29, 1999
Ron Smith, Extension Horticulturist
North Dakota State University
Q: I just planted three hardy, shrub-type roses. They were purchased from a nursery, potted, and already in bloom. Should I fertilize them? Or is it too late in the year? I'm watering like crazy, because it is so hot now. Any other tips for these late-planted roses? (Bismarck, N.D., e-mail)
A: Yes, new roses should be fertilized now. That will help to get them established, and no matter how carefully they are handled at planting time, expect some set-back. I'd give them a shot of Miracle-Gro now, in early August, and then call it quits for the year. Watch water splash on the foliage, so that you don't encourage the development of black spot fungus!
Q: My rhubarb leaves have holes in them from a grub. What is the best way to treat them and when is the best time? Would it poison the stalks? (McIntosh, Minn.)
A: The critters you see feeding on your rhubarb are likely slugs. A sprinkle of salt on them will take care of those you hit. For the unseen others, get a bait know as "Slug-getta" and that will bring the population down significantly.
Q: When the asparagus is no longer being cut, can the patch be sprayed to kill the grass/weeds? If so, with what? In previous articles you have suggest chemicals such as Dacthal, Devrinol, Poast and Prism for use in strawberry patches. Can any of these be used after the strawberries are harvested? I found the product Preen, but it says to use only on Beach strawberries. What are they? (Tripp, S.D.)
A: Yes, you can use Poast on the asparagus. Beach strawberries are, I think, the nonedible ornamental form.
Q: We have some kind of thistle that we thought we destroyed last year, but it came back. Can you tell me how to get rid of it? (Mansfield, S.D.)
A: It appears that you have a bull thistle. I would suggest applying Trimec directly to the plant--and do so as soon as possible! We don't want those plants to have any young ones sprouting up! Keep in mind the seed is very viable, blows easily in the wind and will establish just about anywhere. So maintain your vigilance!
Q: Can you tell me what the problem is with my cotoneaster? They are turning brown in early summer with dried up leaves. (Tappen, N.D.)
A: Your problem is threefold: one, fireblight, a bacterial infection that shows symptoms of toasted leaves beneath a Shepherd's crook on a branch; two, oystershell scale; and three, Leaf Spot fungus, the brown spots on the leaves not hit with fireblight.
Now the $64 question: What to do? Well, any one shrub that has all three of these maladies should probably be taken out. But, for the fireblight, try pruning out affected branches and spraying with bordeaux mixture. For scale, spray in spring before leaf-out with dormant oil. And for the leaf spot, spray with Daconil 2787, an all purpose fungicide.
Q: Can you tell me why my apple tree is drying up on the tips? What can I spray the tree with to make it stop? (Streeter, N.D.)
A: Your apple is getting hit with fireblight, a bacterium. You can spray it with Agristrep or Streptomycin to prevent further spread, along with cutting out affected branches. This is a common problem this year with the heat, rain and wind we've had across the region. So you have a lot of company!
Q: Last fall in an effort to "lighten" our heavy soil we added wood chips and saw dust to my flower beds. This year many of my perennials died, and the other flowers I planted are stunted--even the daylilies. Should I remove the soil, since sawdust ties up the nitrogen in the soil or will Miracle-Gro help? (Breckenridge, Minn.)
A: You need not remove the soil. Adding nitrogen (N) in any form will help considerably. Miracle-Gro will do, as will urea. In time, when the sawdust and chips weather, you will not need to add the additional N, and the material you added will help to condition, or as you say, "lighten" the soil.
Q: I'm having a problem with my arborvitae. What do you advise? (Hoven, S.D.)
A: Your arborvitae leaf has a minor infestation of scale, an insect whose mouth parts allow it to pierce and suck. In low numbers it presents no problem, but I'd suggest you monitor their population and prune off any branch tips where you find them getting started. Resist spraying for now, as natural predators may do the job for you.
Q: A weed that we have identified as common mallow is taking over our lawn this summer. I would like to know how to eliminate it. (Bowdle, S.D.)
A: Common mallow does not take over lawns, but ground ivy (Glechoma hederacea) does. The two are similar in appearance, but strikingly different in many other ways. Mallow is an annual while ground ivy is a perennial; mallow does not root at the nodes while ground ivy does; mallow is easily controlled while ground ivy requires persistence to eliminate. I suggest repeat applications of Trimec--now and again in September. That should take care of most of it, with some touch-ups in the spring.
Q: I am writing in regards to the person asking about the crown of thorns blooming. I don't think your advice about throwing it away answered their question. My advice is to place it in cool temperatures, 55 F to 60 F, for two to three weeks and shorten the daylight, which is achieved easily by placing a paper bag over it each at 6 p.m. and uncovering each morning. (Cando, N.D.)
A: Thanks for your good advice on the crown of thorns! You are right to reprimand me for my answer--I deserved it--and I'm sure the reader's will appreciate your sound advice.
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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