Ron Smith, Extension Horticulturist
North Dakota State University
Q: When is the best time to transplant blue spruce and red cedar trees? These trees are anywhere from 2 inches to 1 foot tall. Are there any other hints to get them growing where I want them to grow? (Northville, S.D., e-mail)
A: When the trees are about 1 foot high seems to be the best time. They are large enough and are easily handled. You can, of course, plant them larger, as it is done successfully all the time. But if you know now where you want them to be permanently, the longer they can sit undisturbed in that site, the better the overall growth will most likely be. The timing is either early spring (March/April) or early fall (September/October).
Q: My neighbor across the street moved away and gave me a gorgeous 7-foot-tall Queensland umbrella. He kept it away from the window, as the sun shines directly in on his side of the street. I have solar screens on my windows, but the sun tends to come through diffused anyway. Since I’ve had the plant, the bottom row of leaves are turning speckled, with yellow and green spots. My former neighbor fed the plant every three weeks with a name-brand plant food and misted its leaves every week. Do you think this plant will acclimatize on its own? How often should I water it? Should I install grow lights (I have some fluorescent lights on hand), and if so, how many hours per day should a plant like this be exposed to fluorescent grow lights? I'm normally good with small plants, but this big beauty has me stumped ... and worried. (Kennewick, Wash., e-mail)
A: First of all, congratulations on being on such good terms with your neighbor that you would be given such a fine specimen. The umbrella tree will require bright-but-indirect light to maintain its present foliage cover. It is, however, one of the most adaptable plants for acclimatizing to lower light levels. It does this by dropping some of the older leaves first, until it is at equilibrium with the energy input. The plant will be better looking and you likely happier if it is given strong indirect light--fluorescent being acceptable. Give it eight to 10 hours at first to see how the plant responds. If it continues to lose foliage, up the duration to 12 hours or more. Keep in mind that the farther the plant is from the light source, the less the intensity of the light reaching the plant.
There are three important light factors that affect the survival of plants: intensity, duration and quality. If you can borrow a light meter from a local florist or greenhouse, try to position your lights so that between 150 to 200 foot candles (fc) are at the surface of the top part of the plant.
Watering is not a problem. If you are not getting any new growth being generated due to low exterior light coming into the window for the season, then keep your plant on the dry side. As the plant begins new growth with lengthening days (either from you or Mother Nature), then keep the soil moist to the touch.
And here’s one final important point: Keep the foliage wiped clean with a water-soaked sponge at least once a month (top and bottom) to keep dust from accumulating and to prevent spider mites from taking up residency.
Q: We have a two-acre yard that we've been having problems with since we moved here two years ago. We have every weed imaginable and are at a loss as to how to control them. I was wondering if we could use Trimec to control ground ivy, dandelions, chickweed, quackgrass and all the other weeds. We planted 125 bare root trees this spring and don't want to damage them. We would like some type of universal weed control. (e-mail)
A: Sounds more like a job for Roundup than Trimec. Roundup will take out anything it touches that is green, while Trimec takes out only broadleaf plants (not grasses). Roundup also does not have any residual soil activity, so you can worry less about any negative effects on your tree plantings.
Q: I purchased a red bougainvillea in full bloom. I planted it on the south side of the house in full sun. Now the plant has lost many leaves, and many of those that remain are brown. Please help. (Ft. Lauderdale, Fla., e-mail)
A: It sounds as though you planted the bougainvillea in the right location--the hotter and more sun these plants can get, the better. My guess is that the plant may not have been acclimatized completely to the outdoor environment, or that you got one that had a root rot disease. If you can get your fingers between the woody thorns and scratch the bark, check to see if the cambium is still green beneath the outer bark. If it is, it will likely come back; if it is light green or brown to yellow in color, the plant is history. Take it back to the nursery and get it replaced with a healthy one.
My experience with these plants is that they are trouble free and grow pretty much like scrambling weedy vines. The bougainvillea usually needs regular heavy pruning to get it to look its best and produce flowers.
Q: I bought and planted an amur maple shrub this spring because I had seen some beautiful ones in a nearby park last fall (about 5 feet tall). Today when I was walking, I went to look at the amurs in the park to see how much they had grown since last year. One had two of its branches dead, and the others' leaves were being eaten away by something. My little bush is still doing fine, but I am wondering if they need some sort of special care and what sort of bug attacks them. Regina, Saskatchewan, Canada, e-mail)
A: Usually the amur maples are pretty indestructible, although they can be hit by cottony maple scale, fall webworm and maple bladdergall mite, as well as a host of other insects, such as sawfly larvae and any number of leaf-munching beetles.
Amur maples have been known to be injured by severe winter temperatures, which could place them under stress and make them attractive to destructive insects. Generally this is what happens to seedling selections that are planted out, not cultivars that have been selected for superior performance in many areas.
Encourage good growth of your amur maple throughout the summer with watering and fertilization. Do not fertilize after Aug. 1 to allow plenty of time to harden up going into the winter. Place a protective barrier around the trunk for the winter to keep the cottontails from debarking the tree (keep in mind where the typical snowline is in your area). Practice selective pruning after leaf-out in the spring and remove any dead or cankered wood to limit harboring places for pathogens or insects. Finally, keep the grass, especially turfgrass, away from the base of the tree, and it will establish faster and grow much better.
Q: I was wondering if you new any way to get a mum to bloom earlier than frost. I have about 20 plants by my garage, and they have been there for three years. The first year they boomed in August, but the last two years they did not bloom until October. What can I do? (Morris, Minn., e-mail)
A: My best suggestion is to move them to a sunnier location, where they can get sun most of the day. Mums move easily, so you don't have to wait for a particular time in the season to carry out the task. Don't over-water or over-fertilize. If they still flower too late, then I'd suggest dumping them and making a selection from either NDSU’s or the University of Minnesota’s recommended list.
Q: We have a caragana shrub in our backyard, and it is a great privacy border. However, nearly every summer green aphids invade the peas and become a nuisance. We were wondering if these aphids cause damage to the shrubs and how they can be dealt with. They seem to suck the life out of the pea until it dries up and falls off. Any information you can give us regarding this would be greatly appreciated. (New Rockford, N.D., e-mail)
A: You might want to try spraying the shrub border with neem, a biological product that controls aphids and other plant destructive insects. I suggest applying the material early in the season as the pods are beginning to develop. Some non-biologicals that are effective for controlling aphids are Sevin, malathion, Orthene and methoxychlor.
Q: I’ve got questions regarding the Colorado blue spruce trees I planted two years ago. The trees are now about 2 feet high. Expecting a few not to make, I planted them about 4 feet apart in a row about 90 feet long. The soil is clay-loam mixture (Parshall, I believe). All the trees look healthy but are growing slowly. I would like to thin them out, at least every other one. Is it OK to do that now or should I wait for fall/spring? Also, should I prune them to encourage faster growth? (Dickinson, N.D., e-mail)
A: Early spring or fall after a couple of good frosts would be the better times to move the trees. Pruning them is unnecessary and not recommended, unless a double leader needs to be corrected. As they establish more, their growth rate should improve somewhat.
If you are going to have someone move the trees for you, make sure you get someone who knows what they are doing. If you do it yourself, have the new holes pre-dug before digging up the trees. Water them in well.
Q: Will peonies eventually die off if the foliage is completely cut off at the end of the bloom period each year? (Valley City, N.D.)
A: Absolutely! The foliage is needed to make carbohydrates to store in the root system for growth and blooming next year.
Q: I have apple trees that have apple cedar rust with apples on them. A local nursery told me to spray them with Daconil, which I did about a month ago. Now I have been told that I cannot eat the apples since they have been sprayed with Daconil. Is this true? (Kansas e-mail)
A: Daconil is a turfgrass fungicide and should not have been used on an edible crop like apples. The product was used off-label--in other words, illegally. Once the disease sets in for the season, there is no effective control except sanitation at the season's end.
Next spring, when the flower buds turn pink, spray with a fungicide containing zineb or ferbam. Spray again at 75 percent petal drop and then again about 10 days later.
Another control is to find the alternate host, juniper, and remove the fruiting bodies that are obvious in the late winter or early spring. Or, simply remove all junipers within several hundred yards of your tree, if possible.
Q: I have seen a number of products used to control early and late blight on tomatoes. These products are chlorothalonil, Daconil and captan. The captan is in powder form, and the other two are suspensions to be mixed with water. I have found that the water solutions or suspensions are easier to use and seem to cover the leaves of the plant better than a powder.
Which of these products do you recommend, and how often should an application be made? Are there any new products on the market at this time, and can these products be used to control apple scab and or the apple maggot? (Faulkton, S.D., e-mail)
A: The suspensions are better for coverage, and certainly less drift off target. These products would give some protection against apple scab, but being fungicides, they would do nothing for apple maggot. For the maggot you need Sevin applied at seven- to10-day intervals beginning at the end of June and continuing to about mid-September. This spacing would be good for the fungicide applications on the tomatoes as well.
If the scab has already set in, don't worry about it this year. The apples are still edible. Practice good sanitation by cleaning everything up well this fall and begin spraying with captan next spring as the leaves unfold.
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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: Gary Moran, (701) 231-7865