NEWS for North Dakotans
Agriculture Communication, North Dakota State
University
7 Morrill Hall, Fargo, ND 58105-5665
July 23, 1998
Ron Smith, Extension Horticulturist
North Dakota State University
Q: Enclosed please find a part of a raspberry bush. Each year it gets fruit and then they dry up instead of developing. Please let us know what is wrong with our plants. (Litchville, N.D.)
A: Your sample showed gray mold (Botrytis) on the fruit. This is brought on by wet, rainy, humid weather before, during or right after harvest.
Since the disease overwinters in decaying foliage litter, sanitation is important in the fall. Some cane thinning or trellising may be necessary as well. Hold off on the use of fungicides unless the disease cycle repeats next year.
Q: Enclosed is a sample from a Haraldson apple tree that appears to have black specks on the inside where a tree limb broke off. I have been spraying it with Sevin about three times a year. I also have a honeysuckle hedge that gets infected with insects. I have tried spraying Malathion and Isatax and a combination of the two, but to no avail. (Jamestown, N.D.)
A: Your apple tree sample was badly cankered from one or more of several canker-forming fungi. Spraying with an insecticide will not help. I suggest removal of all infected limbs/branches and following a spray program with a multipurpose fungicide.
Concerning the honeysuckle sample, I could find no evidence of extensive insect activity. I suggest you discontinue use of insecticidal sprays and try to control the apparent disease with a fungicide like Bordeaux mixture.
Q: This branch is from my cedar. There are several galls on it, some bigger than these. What are they and what should I do about them? (Wildrose, N.D.)
A: Your tree has cedar-apple rust fungus. This is a disease that needs an alternate host to complete its life cycle—which in this case is an apple or a member of the apple family (hawthorn, Juneberry, mountain ash, etc.).
You did the correct first step in control—cutting the galls off the tree. Try to get them all, if possible, and then spray with Ferbam in August to prevent new infections from developing from the alternate host.
Q: We enclosed our strawberry plants with green-treated landscape timbers, and remember reading something in your column about how arsenic leaches from the timbers. Are the strawberries still safe to eat? (Grenville, S.D.)
A: The amount of arsenic reaching the strawberries would be essentially nothing. They should be perfectly safe to eat.
Q: I have a snowball bush that was cut off by mistake, and now the blooms on it seem really small. Will it get big blooms on it again? Also, is there more than one kind of potentilla? I saw one with really large flowers and would like to know what kind it was. I have one that blooms a lot smaller, but I like the larger flowers. (Walcott, N.D.)
A: Don't worry, your snowball bush will be just fine—just don't cut it back so late next spring!
There are many Potentilla cultivars on the market. Yellow, white, red, big blooms, small, etc. I count some 56 selections in my reference books. What you saw was likely the Jackman's variety. It has yellow flowers ¼ inch to 1½ inches in diameter. Yours could be the Gold Drop form—a little smaller.
Q: We have five scandia juniper in the front of our house that are getting so grown together that they are hard to keep a manageable size. There are many dead branches on the bottom and I am wondering if we cut the original bushes down to ground level, would they grow back? (New Rockford, N.D.)
A: Always cut juniper branches back to a little wisp of green foliage. This may require loppers first, to be followed up with hand clippers.
This treatment is drastic, usually leaving the plant looking nothing like the original specimen, and the homeowner bewildered. But, they (both the shrub and homeowner) usually survive.
If you want to be less drastic, take about one-third of the old branches back now, and for the next two years, and this will give you the same eventual result.
Junipers respond to annual pruning in summer quite well.
Q: I have had these beautiful delphiniums for six years. They are in a sunny, well-drained soil near peonies and have done well. Last year I lost three of them. They started turning yellow, so I fertilized them and then they died. This year the same thing is happening to the others. What's wrong with them and can I save them? (Parshall, N.D.)
A: The delphiniums are sensitive to soil-borne diseases, and it sounds as if yours are suffering from one of them. At this stage, I doubt there is much that can be done. Sorry!
If you try them again, plant in another location.
Q: My apple tree is suffering from one of the diseases in the "Apple and Pome Disease" bulletin published by NDSU. My question is whether it is OK to wait until next spring to spray the tree or will the defoliation hurt the tree if I wait too long.
I also planted three goldleaf spireas, and placed plastic around the shrubbery to stop weeds. I did poke holes with a garden fork randomly to allow rainwater to seep through. Will the plastic sheeting prevent natural aeration? (Minot, N.D.)
A: A single defoliation will not kill the tree. Defoliation two or three years in a row will kill it. At the stage your sample was, some defoliation is inevitable. Clean up leaves and fruit as they fall. Next spring spray with Captan (or a product containing it) as the leaves open, and repeat at two-week intervals.
You have done the correct procedure in piercing the plastic sheeting. That will allow for some air/water movement into the root zone. It would have been better if you had used a geotextile material, as that would have allowed for better air and water movement and given you the desired weed control.
Q: I have a calla lily and the leaves are turning yellow. I have tried to repot it, but the leaves are still the same. (Carrington, N.D.)
A: It sounds like your calla lily needs a rest. Allow it to dry out for about a month, keeping it in a cool, dark location. Then repot and commence watering, placing it in a sunny location.
Q: Enclosed is a sample of a weed in our garden and flower beds. (Regent, N.D.)
A: I cannot identify the sample you enclosed because it was well on its way into decomposition by the time it arrived. Please send a new sample and make sure that it is dry!
Q: In response to the person who is having problems with snakes in their steps—we sprinkled salt around the area where they were. The snakes will go away, never to return. (Wishek, N.D.)
A: Thank you for the information about snake control. I'm sure it will help many of our readers, and we will specifically pass this on to the person who wrote about a snake problem.
Q: I am writing with information for the person trying to get rid of snakes. My husband poured diesel fuel in the hole where the snakes were, and that took care of them. (Waubun, Minn.)
A: Thank you for the information about snake control.
Q: Enclosed is an article about a snake repellent for the person trying to control snakes. It is called Dr. T's snake repellent, or Snake-A-Way. (Jamestown, N.D.)
A: Thank you.
Q: Enclosed are some leaves of two different tomato plants. Are they blighted or is there something else wrong with them? (Minot, N.D.)
A: Your tomato is blighted with Alterneria solani, a common fungus known as early blight. For control refer to enclosed PP659, "Disease Management in Home-Grown Tomatoes," where cultural and chemical controls are listed. Other readers may obtain a copy from any county office of the NDSU Extension Service, or by calling (701) 231-7882.
Basically, apply water at the base of the plants and avoid splashing, and use protective fungicides like Mancozeb or chlorothalonil.
Q: I have a fairly young maple tree that consistently develops numerous shoots around its base. Why does this tree do this when my other maple trees do not? I also have a cyclamen that is finished blooming and I would like to know how to care for it. (Gary, Minn.)
A: The cyclamen prefers cool, partially shady environments. When it is not in bloom, allow it to dry out, and remove all yellowed and dry foliage. Then, in the fall, repot and commence water/feeding again. Fertilization should be about every two weeks during bloom.
Concerning the maple; it could be due to a number of factors—planted too deep, root injury, or it was grafted on an aggressive root stock. If possible, dig up this fall when dormant and reset to a shallower depth.
Q: We have a problem with the enclosed sunflower plants. They have started to curl up some and have a firmer, drier texture compared to the normal soft-leaved plants. They are located on the edge of a field next to canola that has been sprayed with some type of chemical. Can you tell us what kind of chemical would cause this and will we still have a crop? (New Rockford, N.D.)
A: There is no doubt your sunflowers were hit with a broadleaf herbicide spray, most likely a phenoxy type like 2,4-D or MCPP. On the samples you sent, the damage appeared extensive, and may cause the plants to not flower properly, or be unable to get seed.
I hope this visual diagnosis helps. To get specific about which phenoxy was used, a chemical lab analysis, likely using a chromatograph, would be necessary. The cost would be approximately $250 per test.
###
Source: Ron Smith (701) 231-8161
Editor: Barry Brissman (701) 231-7866