August 28, 2003

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: We have four, 7 to 9 year-old white spruce planted in our yard. The one on the side of the house and the one in the back yard are doing well. The two in the front yard are not doing well. They have all been watered and fertilized the same. Do you have any ideas? (E-mail reference)

A: Genetic variation, water run off from the roof, difference in planting depth, variations in soil structure, snow accumulation, salt spray from the road, herbicide residue from lawn care operations, migration of pesticides from subsurface drainage and exposure to the elements, especially during winter months. Enough ideas?

Q: This is my second year of trying to establish raspberries. I have 30 plants in three rows planted 6 feet apart. The first year I watered them a great deal and was told I probably killed them by overwatering. This year I planted in the same area and all but one leafed out. They are on the north side of our property in the center of the yard and in full sun from about 10:30 to 5:30 each day. The plants leaf-out and then the leaves turn brown around the edges and die. I pulled up a dead plant and found plenty of moisture and damp soil around the roots but they snap like an old dried twig. Some of the plants actually produced a few berries this year. (Grand Forks, N.D.)

A: Sounds like the raspberries are being wiped out by a soil borne disease such as armillaria root rot or verticillium wilt. Plant in a different location and use only certified disease-free planting stock. Keep the new plantings moist but not soggy.

Q: I have a sandbox in my back yard that I would like to convert into a flower garden. I planted some moss roses that are growing but not spreading out. The box is wedged between a 5-foot fence on the west side and a fort/storage shed on the east side. It gets direct sun for a few hours in the afternoon and early evening. Any suggestions on what will grow in sand or should I add soil to it? Any ideas as far as blooming shrubs or perennials? I'm not much of a gardener to be honest but I love things that bloom profusely and for long periods of time (Fargo, N.D.)

A: Mix in some good quality loam and plant some shade tolerant plants like pansies, wax begonias or nigella. Portulaca needs a full day of sunlight, not just the few hours they presently get.

Q: My rhubarb was ruined by wind in late June. I pulled it out and now the new growth is young and tender but your last article said not to use anymore this year. I've heard before not to use rhubarb after July 15 but I'm wondering why? (Arthur, N.D.)

A: The leaves are needed for food production next year. Removing too much of the foliage beyond mid-July will reduce the carbohydrate energy the leaves can produce resulting in a weaker plant in future years. This would be especially true in your particular case because the plants were damaged early in the season. Be patient, you can enjoy it next season.

Q: I have an old weeping willow tree that has several holes in it. Birds and squirrels are constantly putting new holes in it for their nests. We have covered some holes with wood blocks. Is this the appropriate thing to do? I'm afraid that if the animals continue to nest in the tree, it will die. (E-mail reference)

A: Old willow trees are to birds and squirrels the same as old shoes are to household kittens, cozy things to get into. You would have a hard time trying to control all the activity that goes on in such a tree. You are better off allowing nature to take its course. In all my years as a horticulturist interested in trees, I can honestly say that I have never seen a willow tree completely killed off by anything, disease, insect, or otherwise! They can look terrible and have many dead branches and limbs but there is always some new growth taking place. I have cut a couple of old ones down and am amazed at the amount of animal life that had taken up residence.

Q: I bought a potentilla plant about three weeks ago. It had pretty yellow flowers on it and looked healthy. I planted it in full sunshine as I was told to do. I watered it well after planting and have watered it several times since but it’s all brown and looks dead. I even sprayed it with Miracle-Gro. (E-mail reference)

A: I would take it back to the retailer and see if you can get a replacement. These are usually very tough plants. Unless you did something grossly wrong such as planting too deep, washing all the soil off the roots or allowing the roots to dry before planting, they should have transplanted from the container to the site easily.

Q: We are moving from Bismarck to Ashley. We have flowers, shrubs and bushes we would like to transplant. We are moving in February so of course we can't transplant anything then. Is it possible to transplant them to a temporary location (like the garden) this fall and then to the permanent location this spring? We don't have the permanent location ready for plants. How soon should we transplant? Do they have to have a period of growth this fall? Could we put them in huge pots for winter storage? Will they freeze out if left outside? How much care do they need during the dormant stage? Some of the plants we would like to transplant are lilacs, peonies, rose bushes, lilies, irises, hostas, a variety of scrubs and strawberries. (Ashley, N.D.)

A: It sounds like you are cleaning out your present landscape and moving it to your new location! Don't you think it would be more prudent to simply purchase new plants? You are creating a lot of work for yourself but the choice is yours to make. The plants should not be dug up until they go dormant this fall. Leave as much of a root mass as you can comfortably handle. When you get to the new site, plant them temporarily in a trench at a 45 degree angle and cover the roots completely. After the soil freezes, mulch the area completely with straw and don't worry about applying too much. It would be best if the temporary planting site had an east or north exposure to keep the plants from thawing too early in the spring. When you transplant next spring, be sure to trim the aerial part of the woody plants back about a third of their length. Plant at the same depth they currently are and water in. You have a lot of work ahead of you. I’m glad it's not me! I still think it would be easier to start new with fresh plantings from a local nursery.

Q: I have broad leaf grass in my yard that I want to get rid of. It must have been in some seed I purchased to over-seed thin areas and patch bare spots. It has a broad leaf with clasping auricles with pubescence on auricle margins and no pubescences on the top or underside of the leaf. It grows prostrate to the ground. (I had help with the description from an agronomy graduate.) Can you tell me what it is and how I can get rid of it without applying roundup on my whole yard and starting over? (Casselton, N.D.)

A: What you are describing (and I thank you for doing it so well!) comes closest to quackgrass, agropyron repens. That's the good news. The bad news, there is nothing that is selective to remove it from a lawn situation. Live with it or start new by using Roundup. I doubt that it came in with the seed. If it was any kind of quality seed, quack would have been removed in the cleaning process. Sorry.

Q: I had a gardener ask me why the blossoms would suddenly fall off his tomato plants. Can you explain that one? Also, why would cucumbers suddenly quit blooming? (Mandan, N.D.)

A: One answer to both questions, high temperatures and a lack of adequate moisture. While both like warm temperatures, the hot weather we've been having and the lack of consistent rainfall will cause both blossom abortion and non blooming. Even our zucchini plants are way down on production this year and that's saying something!

Q: Could you please tell me how to prevent my pea plants from getting a white mold that eventually kills them? It happens every year around the beginning of August no matter how dry it is. I always water with soaker hoses. (E-mail reference)

A: There are several approaches to controlling this disease. Rotate planting sites but only in un-shaded areas and where good air circulation is available. Use resistant varieties and pre-wash the foliage with plain water. Spray the foliage with fungicidal soap or a baking soda solution.

Q: I am having a problem with my spider plant. It is wilting and now it only has two long stems that grow anything. I water it and put it in the sunshine. I also put it outside on occasion. Should I take what is left of it and replant it? Right now it is in the same plastic pot that I bought it in years ago. I would really like to bring it back to life and watch it grow. They are beautiful plants. (E-mail reference)

A: My gosh, please repot it! Get a larger pot and use pasteurized potting soil then give it a little shot of Miracle Gro., Put it outdoors during the summer. Allow it to get filtered sunlight through the windows in winter. I can almost assure you it will come back because these are wonderfully durable plants.

Q: What causes a sticky white substance on chokecherries? Is there any way to remove it and is it safe to preserve? (Jamestown, N.D.)

A: It’s most likely powdery mildew. Other than washing them carefully, I don't know of any other way of removing the fungus. I would imagine that the temperatures used in making preserves would render any pathogen inert. I can't say anything about the flavor!

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. Note to e-mail correspondents: please identify your location (city and state) for most accurate recommendations.

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Source: Ron Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu