NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
June 15, 2000
Ron Smith, Extension Horticulturist
North Dakota State University
Q: I am currently having a problem with a maple tree in my front yard. The symptoms I noticed about this tree is the leaves are wilted where they droop on the outer edges. There are bare limbs at the top of the tree where no leaves have grown for the last two years. These bare spots are about 12 inches long. The problem seems to be progressing. Some of the leaves are now beginning to turn fall colors on one side of the tree. The tree is about 10 years old and grew much quicker than all those planted at the same time of similar size. I don't want to lose this tree. (Port Elgin, Ontario, e-mail)
A: It sounds as though your tree may be dying from a fungal disease known as Verticillium wilt. This is a disease that typically comes about under well-maintained lawn conditions: regular watering, fertilizing etc. While sugar maples can tolerate some water, putting them in an ecological situation where maintenance favors the grass often results in this wilt.
This fungus kills trees (flowers, veggies and shrubs too) essentially by blocking the vascular tissues. The fungal inoculum is found in the soil and can remain dormant for years, until conditions and a susceptible host arrive to move it into the active, pathogenic stage.
Unfortunately, there is nothing you can do about this disease. Once the symptoms have developed, it is simply a matter of time before total death of the plant. In some cases, it can happen quickly. In others, like your tree, it can take agonizingly long. Sorry!
Q: This coming fall we plan to transplant some green ash trees. My question is, how big is too big to transplant? We have a very nice tree in our tree grove that is about 25 feet tall. We have had good luck with 14-foot trees but want to make sure it will be OK to use this larger tree. (Houghton, S.D.)
A: Larger trees transplant successfully with greater difficulty--usually. I assume you are going to employ a professional tree mover to do the job.
Chances of success are greater if the mover can come in with the tree spade and simply root prune the tree, leaving it at the site. This will cause new roots to grow during the season, thus increasing the surface area and "softening" the blow of being moved to a new site this fall.
Q: Someone wrote in about keeping cats out of their garden, and I have an inexpensive solution to the problem. Cut citrus rinds into small pieces and scatter them where you don't want the cats. Cats detest the smell of citrus and by cutting them into small pieces they are hardly noticeable. This works really well for me. (Milbank, S.D.)
A: Thank you for the advice about controlling cat activity in gardens. I'll have to try it, as we have some that enjoy using the great outdoors around our house!
Q: Can you tell me how to take care of fresh garlic that you buy at the store? They always start growing before I can use them. (Winner, S.D.)
A: Good question! At this time of year their biological clock is kicking in to grow. Lowering the temperature would slow it down somewhat. Room temperature is most conducive to sprouting. Store the garlic close to 32 F in the veggie crisper of your refrigerator.
Q: I bought a big-leaf hydrangea and kept it in morning sun, afternoon shade and gave it a little bit of plant acid since I was planting it in alkaline soil. It went downhill since the transplanting. The nursery told me to plant it outdoors. I also bought another hydrangea (nikko blue); I have it planted and it's just going down hill. I try to water only when the soil is feeling dry on top. I also bought a lace cap hydrangea, which I've kept it in the container I purchased it in. I have tried to move it to three different spots every day, but the plant just gets dryer and dryer. (California e-mail)
A: I suspect the water you are using may be too salty. Do you have a water softener connected to your water supply? If so, that's the reason. If you don't, then there are some other possibilities. First, you may simply be getting the wrong speciesflorist type rather than landscape types. Second, try north-side plantings; even the morning sun may be too strong. And finally, go for the Annabelle cultivar--Hydrangea arborescens. It is hardy from Georgia to North Dakota. If that one doesn't make it in your area, give up and try something else!
Q: Can a 20-year-old lilac be cut way down to improve it? If so, when is the best time to do this? I have the same questions regarding a spirea. And finally, I have a perennial flower bed taken over with quack grass and other weeds. Is there a chemical control or should I just dig the bulbs (mostly iris) and other flowers, use roundup and then replant? When would be the best time of the year to do this? (Jamestown, N.D., e-mail)
A: Lilacs and spirea can be cut back to the ground, but it should be done when they are still dormant in the late winter or early spring. Doing so now may weaken the plants too much to generate a decent regrowth.
I wish there was a magic chemical that would take out only quackgrass! I have had to do it several times with my flower beds. Dig your flowers up and get every last bit of the quack that you can, either mechanically or by using Roundup.
Q: My son has a snowball shrub in Minnesota and it is full of tiny black bugs. What should he use to get rid of them? (e-mail)
A: Try Orthene. It is both a systemic and contact. These are aphids that you are trying to eliminate, and on this species, that is a tough job! So you want to go in with the big guns. Orthene should do it for you.
Q: We have more than a dozen 40- to 60-foot tall hackberry trees amongst our timber and three large ones along the river bank behind our home. All apparently have been attacked by nipplegall aphid larvae. Damage to the dozen or so large trees within the heavily timbered area is so severe that their leaves are very sparse. Some of these trees almost appear to be dead from a distance due to sparseness of foliage. All of this damage has happened rather suddenly, or at least we first noticed the problem only recently. Spraying all of these large trees with carbaryl would be a challenge, but I will undertake anything reasonably possible to save all of these trees, or at least to save the many hackberry saplings. I would appreciate any help or comments you may be able to provide. (Tuscola, Ill., e-mail)
A: Nipplegall would not cause this defoliation. It is more likely a cankerworm or forest tent caterpillar. It could be the insects have already outstripped their food supply and are dying off, or a predator has moved in to bring them under control. If that doesn't appear to be the case, have the trees sprayed with Bacillus thuringensis (Bt), a biological bactericide that kills them as they feed and is safe to songbirds and us as well.
Don't worry about the nipplegall. It will always be a part of the hackberry tree.
Q: I have a miniature rose bush that's about 2 years old. It's doing great, but I noticed that near the very bottom of the plant the leaves are turning yellow on some branches. What should I do so I won't lose the plant? What could be causing this? (e-mail)
A: Miniature roses are nitrogen sensitive. If the leaves are turning yellow from the bottom up, that is my first best guess. Nitrogen is transported within the plant to the new growth. It is done so at the sacrifice of the old growth when there is insufficient nitrogen available to the plant. If you have mulched the rose with wood chips recently, this could cause the nitrogen to be tied up, and unavailable to the plant. I suggest an application of Miracle-Gro or something similar once a month during the growing season.
Q: My mom has a lot of grass in one of her flower beds, which just has tulips and irises in it. Is it safe to spray Roundup or is it going to kill the flowers? Also, she has grass in her raspberry patch, so is it safe to spray Roundup in there or will it kill the raspberry plants? She read somewhere that it was a good idea to put down a lot of straw in with raspberry plants because the straw will choke out the grass. Is that true? (Battle View, N.D., e-mail)
A: Roundup is safe as long as it does not get sprayed directly on the green foliage of ornamental or edible plants. It becomes deactivated as soon as it hits the soil. Straw or grass clippings will help smother weed growth among raspberries.
Q: I just had a 4-foot-tall evergreen tree moved, and the movers took great care in marking the north face of the tree so that when it was transplanted, it once again faced the same direction. Is there any thing to this? (Forman, N.D., e-mail)
A: Certainly, the side of the tree that faces north is different than the side that faces south. It would be like you always keeping your bare back to the south, and your face to the north, when suddenly, the two sides are reversed! Do you think the two sides are ready for the reversal of these exposures? No! And the same is true for trees. They will have a much better chance of adapting to the new site if their compass orientation can be kept the same. It's something I've preached for decades, and have finally found someone who does it ... your tree mover deserves a award!
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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