June 7, 2001

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I have a mixture of potting soil, scoria and river sand as a cactus mix. I got this yellow looking fungus which grew throughout my entire collection. It ends up with large yellow mushrooms coming out of the bottom of the pots. I repotted most of my plants with a new mix. Now I see the fungus is also growing in the new pots. It is almost impossible for me to repot my plants, and I would lose a lot of my larger plants if they went through another transplant. Is it possible to treat the soil with some sort of fungicide? I have tried the general fungus treatments and they have had no effect. (E-mail reference)

A: If I understand your concerns correctly, the fungus is growing in the soil and containers, not the plants per se. If that is the case, don’t you have much to worry about, as what you are seeing is a saprophyte that is growing in a part of your media that is not sterile or pasteurized. Other than aesthetics, it should pose no threat to your plants. When you do get around to repotting, I suggest using media components that have been heat pasteurized or sterilized. You containers need to be sanitized as well. Soak them overnight in a 10 percent solution of chlorine bleach to kill any spores and allow to sun dry completely.

Q: We need a suggestion for a bush or shrub to plant at each outer corner of our three-stall garage. We built our house last summer so don't have any bushes.. The one corner has plenty of space but the other corner is only about 29 x 45 inches as the sidewalk to the front door curves from the driveway. I think something with a height of 3 feet or so would be attractive to the house but it would have to be some bush that wouldn't spread too much. What could you suggest? Our house is sandstone color. (Grand Forks, N.D.)

A: How about a potentilla at the tight corner? It gets about 3 feet tall and has bright yellow flowers almost all summer long. You could plant the same thing on the other corner too, depending on what you want, or you could plant a Clavey's Dwarf or MiniGlobe honeysuckle. Both of those get about 4 feet tall and don't spread extensively.

Q: We have a laurel leaf willow tree, which we planted about eight years ago. It did very well and had terrific leaves until about two years ago when the leaves were much smaller. This tree has about an 18-inch base and has been very healthy. About mid-summer some little leaves turn yellow and just drop off. At the same time the seed pockets, which used to fall off, start to pop open and spit cotton all over the grass. Can you tell me what is wrong with my tree and what I should do about it? (Beulah, N.D.)

A: I could see nothing wrong from a pathogenic standpoint, with the sample you sent in. I would suggest core aeration around and outside the dripline of the tree. You may also want to try vertical mulching around the tree as well. It could be as simple as soil compaction causing the problem after so many years. This treatment will at least give the tree a good opportunity to recover.

Q: In earl May you had an inquiry about diamond willow. I find it hard to believe that you hadn’t heard of this willow. It makes very colorful canes and walking sticks. I looked up diamond willow in my copy of O. A. Stevens and it stated the botanical name as Salix missouriensis. Another source, Flora of the Great Plains, said the correct name was Salix eriocephala Michx. (Napoleon, N.D.)

A: Yes - sometimes things get by me and I need to get informed from people like yourself. Thank you!

Q: I had some evergreen trees moved in from single row plantings to my yard in town. A few existing large old evergreens seem to have needle cast or something similar as they are losing needles from inside to outer tips. Two or three of my large evergreens have lost about half their lower branches and it seems to be working up the tree. What can I spray them with and will it help to spray my new trees? Also, should I fertilize these new transplants, and if so with what type of fertilizer? (Wimbledon, N.D.)

A: Spray in early June with Bravo; repeat in early July with all your evergreens. A liquid fertilization would not hurt. Miracle-Gro or Miracid can be used.

Q: My husband and I argued over this one. This winter he would dump his dead minnows on the lawn after his fishing expeditions. I think this kills my lawn and he argues that it fertilizes the lawn. Which one is it? It seems like the area in which he dumped the minnows the grass is still brown and not growing very well at all. Hopefully you can settle our argument. ( New Rockford, N.D.)

A: I think I should change my name to Solomon, since I get so entangled with solving spousal arguments! Here is my answer: You are both right. The minnows act as a fertilizer eventually, but the water he dumps with the minnows temporarily thaws the snow enough to encourage snow mold pathogens to develop, resulting in the dead areas of your lawn. It would be better if you had a compost pile that he could dump the minnows on, allowing them to be digested by the microbes into compost, which is certainly more useable and not as unpleasant as seeing dead minnows strewn about on the lawn. I hope this brings peace to your marriage!

Q: For the last two or three seasons I have had a series of circles of dead grass running across the middle of my front yard, which faces south. A larger spotty patch is on the east side and from that there is a series of circles crossing my yard west, looking like an elephant walked over the lawn. I do have five oaks in the front and there is considerable shade. Each spring I rake the spots well, spread some dirt on them and seed them with a Scott's shade/sun mixture of grass seed. (This past fall I re-seeded the spots.) The seed grows, looks okay for the summer, and then each spring the spots are back. In fact the half of the lawn closest to the house is becoming increasingly bare and bedraggled. What can I do to solve the problem and get back to the thick, thriving lawn I once had? The oaks have always been there so it doesn't seem shade would be the problem. (Garrison, N.D.)

A: Shade grown grass is more vulnerable to pathogens and other stresses than grass grown in full sun. Based on what you have told me about the pattern of infection, I believe it is one of the snow mold fungi that is causing the problem. This fungus typically develops on well-tended grass that goes into the winter in a tender condition, as is the case with shaded grass, where snow piles up, or the grass and soil is saturated with water going into the winter, or coming out of it.

I suggest core-aeration of the lawn area. It would also benefit the oaks as well. This improves the surface drainage, helping to dry the soil, and altering the environment for the pathogen. Make the last mowing in the fall shorter by about an inch to cut down on material for the pathogen to establish upon. There are fungicides that can be applied in the fall before winter arrives, if you want to go that route, but I would suggest it only if the cultural practices don't work first.

Q: I have a peace lily that needs to be divided. How do I do that without harming my lily? It means a lot to me. Thank you. ( Moorhead, Minn.)

A: Now, the spring, is the best time for division. Gently pull the rhizomes apart, making sure that each piece has at least two or three leaves attached. Plant individual pieces in 3-inch pots in a peat-based potting mixture, burying each piece the same depth as the entire rhizome was planted. Do not fertilize for three months.

Q: We have been planning on planting some arbor vitae along the back of our lot for privacy and to cover unsightly power boxes. The question is, what type should we plant? We've been thinking about Emerald Green or Pyramidal. What is the real difference between the two and what are the planting guidelines for them? I think the Techy would be too big, but we don't want something that isn't going to spread nicely. The last thing we want it a stiff wall of trees. We live in Wisconsin and our soil is full of clay. (E-mail reference, Wisconsin)

A: I suggest either the Emerald or the Brandon; both are more resistant to winter burn, and extremely hardy to -40 degrees F. Both get about 15 feet tall and a spread of 3 to 4 feet. You would want to space them about that distance apart (main stem to main stem) if you want complete coverage. Arborvitae are not fussy, being a standard landscape plant. They will grow well in your Wisconsin soil. I would simply give them a shot of Miracle-Gro at planting time, and keep them watered--not soaked - for the rest of the growing season.

Q: About seven years ago I planted a lilac bush (unknown type) on the northern coast of Maine. It is nice and green but has never bloomed. It is in a sunny, well-drained area. I have never pruned it--I'm afraid I'll kill it. Should I? How? I have never fertilized it. Should I? With what? Any help will be greatly appreciated. (E-mail reference, M.E.)

A: A lilac that has never bloomed in seven years is very unusual. You are probably too good to it, or it is growing in too much shade. If it isn't in shade, I suggest some "traumatic stimulation" to get it to set flower buds for next spring. Take a straight-edge shovel and drive it into the soil about 5 feet from the plant in about six different places. This will reduce the root system's ability to uptake water and nutrients somewhat, but not adversely affect the plant, just stimulate it into the reproductive cycle. If you fertilizer your lawn every year, give the plant a wide berth to keep it from getting the high nitrogen fertilizer that goes onto turfgrass. If you have it in shade, either remove the shade by selective pruning of the offending tree, or move the plant (this fall when dormant) to a full sun location.

Q: Is there a special paint that you use when trimming apple trees? What is the best time to prune and should you use paint to paint the end of the cut? (Steele, N.D.)

A: You are already too late to prune this year; and no, a tree paint is not needed or suggested. Research has shown that it cause more problems than it solves.

Q: Eleven years ago at NDSU's centennial celebration, my mother-in-law and now husband were given a Siberian pine tree as they left the festivities. I would like some information on this tree before it gets transplanted to my yard. What are it's growth characteristics and what environment does it prefer? (Watertown, S.D.)

A: I think you must mean Siberian larch; there is no such species as Siberian pine.

This deciduous conifer is a beautiful tree that needs no special care, just a place to grow. They can get over 50 feet tall, so give them plenty of room to grow. I am afraid that you are too late to do the transplanting for this year. I suggest waiting until fall when the needles have dropped off, or early next spring before new growth emerges.

Q: We have planted three Dakota Centennial ash trees. Would it be possible to get more information on how to take care of them? They are planted in a sidewalk box. Is there anything special we need to know on their upkeep. (E-mail reference)

A: The Dakota Centennial Ash, selected by Dr. Dale Herman, is a beautiful tree, needing no more care than the run of the mill green ash. It will get about 40 feet tall and 35 feet wide at maturity. It was selected for the oval canopy it has at maturity and the fact that it proved to be hardy throughout the trials across North Dakota. Be sure to keep them well watered through the first two to three years of establishment. Make sure the planter box is never saturated, nor bone dry.

Q: One of our lilac bushes started blossoming, and then within a couple of days one half of it started wilting and that half of the bush has white spots on the trunk. What is wrong with it? (E-mail reference)

A: Sounds like borer activity to me. Cut out the affected parts and burn or otherwise dispose of them. Spray with permethrin or lindane, and try to keep the shrub as stress-free as possible with ample water and fertilizer.

Q: If a homeowner has cedar apple rust on junipers, would it be wise to avoid planting any type of apple, whether its flowering crab, regular apple or crabapple? There is a little distance between the junipers and where the flowering crabs (if that's what they planted) would go. What are the more tolerant ones? ( Cando, N.D.)

A: The fact that the juniper is showing CAR now is an indication that the alternate host--apple or crabapple--is nearby. Picking the orange, spore-bearing structures (golf ball size) off the junipers would help appreciably in controlling the spread of the pathogen. Some cultivars resistant to cedar-apple rust are Donald Wyman, Indian Magic, and Prairiefire.

Q: I have a bloodleaf maple tree that is 10 years old. Last fall the leaves on one half of the tree turned brown and rolled in prematurely while the other half had brilliant foliage into the fall. This spring, the half of the tree that retained late foliage has beautiful red leaves while the other half is nothing more than limbs. Some of the limbs are a healthy red color while still others look dead. Toward the base of the tree, new leaves are starting to appear. What would your educated guess be as to what is happening to this tree? Should I prune off the dead limbs now? (E-mail reference)

A: The prognosis doesn't look good. It has been devastated by either canker disease or borers. It is important that you get the cause identified by someone locally before doing anything else. If the new leaves coming from the base are the same color as the original bloodleaf, then you may have a chance; if they are not, then you are better off just digging the tree out. It is a shame to lose a tree like that after 10 years.

 

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