NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
November 18, 1999
Ron Smith, Extension Horticulturist
North Dakota State University
Q: I was told that there is a pre-emergent herbicide for crabgrass and quackgrass. If so, will it kill the rest of my lawn? (Mohall, N.D.)
A: There are pre-emergent products available to kill crabgrass, an annual that appears in lawns beginning midsummer. These include products with chemicals in them such as trifluralin or pendamethalin. There shouldn't be any problems with the pre-emergent killing your lawn unless you are seeding it, because it only disrupts seedling germination.
Quackgrass, on the other hand, is a little more difficult to control because it doesn't spread by seeds like crabgrass, but instead, by its underground rhizomes. Post-emergent herbicides such as Vantage should be applied by spot spraying directly to the quackgrass.
Q: Can you tell me why my spider plant tips are turning brown? (Minot, N.D.)
A: Tip browning is a common ailment of spider plants. They are sensitive to fluorides and other salts found in public drinking water supplies. These accumulate in the soil or potting media and cause problems for the plants.
The best advice I can give is to periodically leach your plants when you water them. This means to give it a thorough watering that will wash the excess salts out of the pot. Allow the water to drain out the base, and them dump it (don't let the water stand, as the soil may reabsorb it!). Also, if possible, use either rain water or distilled water. You can continue to use miracle gro, but try mixing it with distilled water or rain water. If it has been more than two years since the plant has been repotted, it may be time! I hope this helps!
Q: I have a question about one of the trees in my yard. I am not sure what kind it is. It is a small tree that starts out in the spring with green leaves that quickly turn purple. The leaves stay purple until fall and are long and slender.
After the leaves dropped this fall, I noticed three branches had a dark growth on them. It is an ugly black thing that has clearly grown around the branches. Is this a bug or a disease? What can I do about this? Will this spread to the other tree like this I have?
I have also planted several other trees for windbreaks and shade. My soil is mostly clay, so I have to be careful about iron with the Silver maples and try to put Miracid on once or twice a year. I have also started mulching my grass clippings and putting them around the trees and rototilling the mulch into the dirt. I have a lot of ants in my yard, and I have not done much bug spraying on the trees because of the expense. Any other thoughts? (Minot, N.D., e-mail)
A: The tree sounds like the Canada Red chokecherry, and the problem sounds very much like black knot fungal disease. Cut out the branches with this growth sometime before new growth begins next spring, and spray the tree with lime-sulfur prior to leaf-out. Once infected, it is unlikely that the tree will be worth very much. You can try for a couple of years, but don't be surprised if you end up taking the tree out completely. I would suggest spraying all deciduous trees with the lime sulfur while they are still dormant prior to leaf-out. This is a very effective fungicide. Sulfur by itself, is a very effective fungicide, but adding lime to it causes a chemical change that allows the sulfur to penetrate the leaf tissue and adhere to the stems of the branches, thus killing any spores that will germinate in the near future or any that have sprouted recently.
I suggest a follow-up of Captan after leaf-out. The spray schedules must be used in coordination with a regular pruning of any of the knots that show up. Go back beyond the swollen canker about 6 to 9 inches to make the cut to be sure that any spore migration has been removed. Keeping a protective spray on the uninfected tree will be beneficial.
This disease has become rampant with this particular species--so much so that it makes it difficult to recommend it as a desirable plant to use in North Dakota landscapes.
Your action with the mulch is good--keep it up. Ants are not a problem unless they get into your dwelling. Allow them to do their thing in your yard, they make good soil aerators and mixers. It sounds like you've taken all reasonable steps to have a healthy landscape. Enjoy!
Q: Should I spray my fruit trees with any kind of spray at this time? They are plum, apple, cherry, apricot etc. Also I have an apple tree with yellow delicious apples, but lost the name of the tree. Is there any way to identify it and what would you need to identify it? (Hague, N.D., e-mail)
A: All the spraying is done in the early spring or late winter, prior to leaf-out. I suggest a lime-sulfur and dormant-oil spray at that time--these take care of most overwintering insects and diseases.
If you have an apple tree with yellow delicious apples on it, then that is the name of the tree. I do not try to identify apples any longer. It turns out to be too much of a good guess or worse, a shot in the dark!
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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