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Ron Smith answers reader's questions about the world of plants and gardening.

By Ronald C. Smith, Horticulturist

NDSU Extension Service

Q: I am a 1980 NDSU graduate and now live 100 miles southeast in Alexandria, Minn. I have three acres with beautiful native maples, hackberry, ash and elm trees. We have a hackberry that is more than 200 years old and many of the maples are more than 100 years old. About an acre in the back of the house is a bare field. It used to be alfalfa, but the weeds have taken over. What can I plant that will grow in a hurry for privacy and will blend in with the rest of our property? I have planted a triumph elm and 20 bare-root chokecherries, but that is about it. I do have 35 Norway spruce planted around the bare field. (Alexandria, Minn.)

A: Fast growers are silver maples (I'd suggest named cultivars), poplars and willows. In the evergreen category, I would opt for Ponderosa and limber pines. For shrubs, staghorn sumac is one of my favorites because it spreads quickly through rhizomes and has an attractive fall color. I hope this is what you are looking for; if not, get back to me.

Q: Is sumac invasive? Would it spread to our native plants underneath the maple tree canopy? (Alexandria, Minn.)

A: The species is invasive, but I've never considered it annoying. If you don’t want to take any chances, go for the cultivar Rhus typhina (Bailtiger) tiger eyes staghorn sumac. This unusual sumac has purplish-pink stems with exotic cut-leaf foliage. Tiger eyes starts out chartreuse in the spring, turns bright yellow in summer and blazes scarlet orange in the fall. Tiger eyes is more compact than the species and is not considered invasive. It prefers well-drained soil, but adapts well to poor soils and urban situations by exhibiting good pollution tolerance. It is hardy in zones 4 to 8. I encourage you to consider this striking beauty as part of your planting scheme.

Q: I like the sumac idea, but not for the entire acre. Do you have any other suggestions to mix and match with sumac? As I said earlier, my wife wants some chokecherries planted and I did have some success with American highbush cranberries in our front ditch. I have three silver maple transplants and a triumph elm growing. (Alexandria, Minn.)

A: An entire acre of tiger eyes sumac would not be a very good idea. Some of my favorite for your consideration are elderberry bushes (good flowers with bird-attracting fruit), nannyberry or blackhaw viburnum (beautiful in every season of the year), common and Japanese tree forms of lilac (different blooming times), mountain laurel (needs to be sited in full sun for good flower development), honeysuckle (fragrant flowers and bird-attracting fruit) and winterberry (be sure to get both sexes for berry production). Some of these plants, along with your trees, would look great. Also, there is a low-grow cultivar of sumac that makes a nice ground cover that might be good as a foreground planting.

Q: I went online tonight to find out the type of tropical plant I've had in my home for more than 10 years. I think it is a dieffenbachia. I’ve named the plant Henry. After moving into a new house, Henry began to develop some peculiar wasting in one of the trunks/branches. My mother-in-law feels that I neglect Henry. The plant has not needed much care and seems to enjoy infrequent watering. However, when the branch began to waste, I added more soil and tried to cover it up. Apparently, this was not the correct approach because the problem has moved up the branch. The leaves are still full, but droopy. Now it seems to be severing itself off several inches above this most recent wasting. Do you have any ideas? If I cut it off at the severing point and stick the top part in the soil, will it continue to live? (Grand Forks, N.D.)

A: It looks like that branch has developed a canker disease. I would suggest complete removal and disposal of the branch. I would suggest getting Henry more light from indirect sunlight or from a plant light source for 12 to 13 hours a day. The trunks should not be spindly. If your mother-in-law thinks you are neglecting the plant, ask her for suggestions. If she has some, take her up on it and see what happens.

Q: I received my tulip bulbs in late December. The ground was frozen, so now I have 24 unplanted bulbs. I also have the same amount of daffodils that are unplanted due to the frozen ground. What should I do? Will they still be OK to plant? Someone told me to freeze them, but didn't know for how long. When can they be planted if they are still good? (e-mail reference)

A: The best thing you can do is pack them in dampened peat moss and store them in a refrigerator or outdoors. Freezing will not hurt them. When the soil thaws, plant them, even if they are starting to grow.

Q: I enjoy your blog on growing amaryllis. I have a comment and a question. For the past couple of years, my girlfriend has given my mother and me an amaryllis bulb for Christmas. To my chagrin, she buys the kind that's to be grown in water! I don't have the heart to tell her that I hate that system. Therefore, I wait until the blooms have faded and then plant them in dirt with fertilizer and water. Am I doing this right? (e-mail reference)

A: I must be living in a cave because I've never seen an amaryllis grown in water. However, from what you have told me, it sounds as if you are doing everything right after the bloom is past. Have the results been what you want them to be? (The response is below.)

Q: This label says "Pink Giant Amaryllis Indoor Blooming Kit," with the copyrighted brand name of Bloom Rite. The price was $19.99. It comes in a kit containing a glass or ceramic hurricane-type vase and little, polished river stones. Ostensibly, the amaryllis roots are supposed to grow around and through the little stones. What they actually do is sit on the surface of the stones. The instructions tell me to change the water as needed. If the water level stays the same, how would you know when the water needs changing? Also, the water sits and gets stale. The one I received for Christmas is a dwarf. I planted it in dirt after the blooms faded and it's struggling to survive. It has an underdeveloped root system. The leaves are growing a little, but they are a healthy green. It also has three seeds pods, which I've never had before. I'm giving it fertilizer every two weeks. After the snow is shoveled, I want to go to the nursery and get some rooting powder. I've never used any, but I have a feeling I'm going to need some. If this dwarf will survive, I want to plant my mother's dwarf in dirt. (e-mail reference)

A: These so-called water-blooming kits are a bad idea! If the water cannot drain from the media, it will become stagnant quickly. The container should have some holes in it to facilitate drainage. When future kits arrive as a gift, assuming you can't or won't try talking her out of it, forget the container it arrives in and plant the bulb in a pot with drainage and sterile soil. It should respond beautifully. Also, if you allow seed pods to form after blooming, much of the energy the plant produces through photosynthesis goes into making the seed and not roots or new growth. I suggest removing the flower as soon as it is spent.

Q: I live next to a wooded, vacant lot. It seems the weeds get worse every year, even though I put granular weed protection down when the weeds come up. Is there any weed control that I can use to stop the weeds from coming up? If so, what and when should it be applied? (e-mail reference)

A: Your question is too vague to give you an accurate answer. The weeds need to be identified as to whether or not they are perennial, annual, broadleaf or grass types. I would suggest contacting your local Extension office to see if someone can assist you with weed identification and a course of action that will be effective.

Q: I have two large, healthy ficus trees. I have had them for 26 years. They appear to be root- bound, but are too large for me to repot. They are very healthy, but I'm wondering if there is anything I should do for them. Any advice you can give would be greatly appreciated. I'd really hate to lose them. (e-mail reference)

A: There are plenty of plants that are root-bound and happy with the care they are getting. I would suggest that you continue doing what has brought you such success. Any attempt to repot at this stage likely would set them back or possibly kill them. You can trim them to keep the size manageable and continue on the fertilization program you have been following. You also might consider air-layering a branch or two to start new growth in case the plants begin to go into a slump.

Q: I just got a pot of some beautiful tulips for Valentine’s Day, but I have no clue what I should do with them. Do I leave them in the pot? Do I put them in the yard? If so, where should I put them? How much watering do they need? (e-mail reference)

A: Allow the foliage to die down naturally. Don't remove the foliage while it is still green. When it completely yellows, you can tug the leaves off the bulbs and throw them away. Allow the pot to dry down. Keep the bulbs in the soil and store the bulbs in a cool location in your house until you can plant them outdoors this spring. They will do best in a full-sun location and planted about 6 inches deep. Give the bulbs a good watering and leave them alone. If they are hardy bulbs for your geographic location, they will come up next spring and have beautiful flowers.

Q: I have had a China doll plant for about six months. It was lush and green and growing well until about a month ago. I noticed leaves falling off the branches. After a close inspection, I noticed pale, brown almost cream-colored dots on the leaves. The dots are about a millimeter in length. There is a white fungus where some of the branches have fallen off. It’s in a well-lit area and I am spraying it with water every other day. I would be grateful for any light you can shed on my problem. (e-mail reference)

A: It sounds as if the plant has a bad infestation of mealybugs and some species of scale. Based on what is allowed in your country, I would suggest visiting a garden shop to see if they have the appropriate insecticide to control these pests. If the infestation has progressed too far, it may be too late to save the plant. Don't delay in taking some kind of remedial action.

Q: Last fall, one of my arborvitae trees was infested with cabbage worms. Before I could get some Sevin spray on it, the entire tree turned brown. I decided to leave it for the winter before pulling it out and throwing it away. Is it too late? What causes cabbage worms? We have lived here seven years. The worst insect problem I have had was Japanese beetle, which the Sevin spray took care of. I don't want to lose any more of my evergreens to this pest. Any help you can give me will be much appreciated. (e-mail reference)

A: They say there is a first time for everything and this is one of them. Who diagnosed the insect larvae as cabbage worms? I am not an expert entomologist, but in the decades of my long life, I never have heard of or seen this pest anywhere near arborvitae plants. Are you sure the insects aren’t bagworms? This is a common pest on arborvitae and easily controlled with systemic insecticides. It also could be sawfly larvae, which are voracious feeders on many species of evergreens. Sawfly larvae usually concentrate in masses around the tender growth at the ends of the branches. This problem also can be controlled with systemic insecticides. These and many insects are controlled with systemics that have contact and systemic activity. Orthene is used a lot for this sort of problem.

Q: I am writing about an indoor ficus tree that I own. I’ve had it for 12 years. The ficus is in need of trimming. Do you have any advice or can you direct me to a Web site that will guide me through the process? (e-mail reference)

A: Sorry, I don't. However, I would advise you to do the trimming using common sense. Think twice before cutting. Don't leave any stubs, try to cut back no more than 20 percent to 25 percent of the tree's volume and don't let the bleeding latex upset you. The tree will not bleed to death, but it will be messy. Wear rubber gloves in case you may be allergic to the sap.

Q: Someone in your column was looking to buy winter onion sets. I have some to give away from last fall, so please let them know. My address is Marlene Kouba, 6160 105th Ave. S.W., Regent, ND 58650. (e-mail reference)

A: Will do. The person making the request will get in touch with you with in a week or so. Thanks for your generosity.

Q: I have had my schefflera plant for several years. I’ve transplanted it twice. It has been happy, healthy and growing well until this last weekend. The leaves and stems on one side of the plant have turned a mottled yellow and are dropping off. I have a south-facing, sunny location for the plant. I thought that if I turned the plant around and let the other side face the sun, I would see if the other side turns yellow and the leaves start to drop. It is doing that. I water it at least once a week and let it drain. I’ve never had a problem with the plant before. I also treat all of my plants with an insecticide about every six to eight weeks. Nothing has affected this plant before, so I am puzzled! (e-mail reference)

A: Something's up, but I don't know what it could be based on what you told me. Go to http://www.ag.ndsu.edu/pubs/plantsci/landscap/pp744w.htm to see if you can find something more specific that may help you determine what is causing the leaf drop. This publication, dealing with houseplant problems, was written by a plant pathologist who had ample experience in diagnosing houseplant maladies. If there is an answer to be found, it probably will be found there.

Q: I have about six different kinds of apple trees. Starting in mid-August or so, all the apples on the trees had big blotch spots. The size of the spots were about that of a 50-cent coin or a little bigger. The color was dark brown or black. Each apple had one or two spots. The blotch spots did not penetrate the white core on the inside. Were the apples still edible? We had a dry summer. Do you have any idea what this was and what caused it? Was it preventable? Will this happen again in the future? (St. Cloud, Minn.)

A: The apples were edible, just not pretty looking and wouldn't win a prize at a county fair. This could be some kind of scab fungus that affects just the surface of the fruit. It often occurs at the point of injury through winds, insect bites or hail earlier in the season. It probably won’t happen this season. If you want to be on the safe side, you can spray the tree with lime sulfur this spring, but do it while the tree is dormant. Spray again with an all-purpose fungicide after the leaves have fully opened and the blossoms dropped.

Q: I just bought a new home with a pear and apple tree in the backyard. The trees were starting to produce apples and pears when we moved in. Unfortunately, I’ve never taken care of such trees, so I did nothing. As you can imagine, everything became rotten and bug infested. I ended up picking up all the fruit that fell to the ground and wasn't able to eat any of it. What are the basics that I need to start doing in order to keep these trees healthy? I know that I need to prune and spray them, but that's all I have been told. I don't know what to spray or how to prune them. I'm afraid that I will end up cutting off good branches. (Kieler, Wis. )

A: You did the first right thing, which was picking up the fallen fruit. As spring approaches, dormant pruning will be necessary. It is impossible to verbally describe to you how to prune the trees because pruning is an art and a science. I suggest that you ask around to see if there are any college graduates who majored in horticulture. Another avenue may be finding someone who is a master gardener. Mistakes at this stage could be a disaster for the trees. While the trees are in the dormant stage, a general spray program is needed. This can be done with lime sulfur and dormant oil. The lime sulfur helps eliminate the re-establishment of disease pathogens. The dormant oil wipes out overwintering insects. After the leaves emerge and as the blossoms fall, an all-purpose fruit tree spray (insecticide/fungicide) needs to be applied and repeated about two weeks later. You obviously have two very fruitful tree species. With a little proper care, you should be able to enjoy a bounty of insect- and disease-free, healthy fruit.

Q: I am getting married this August and would like to have gerbera daisies for the occasion. What should I do to successfully raise flowers that would be available in August? (e-mail reference)

A: The average gardener can grow gerbera daisies with basic cultural care, such as full sun, good drainage and balanced fertilization. However, for wedding-quality blooms and dependability, I would strongly suggest that you contract with a greenhouse operator who has had experience growing gerbera daisies. It has been my experience that greenhouse production is far more consistent in quality and quantity than growing them outdoors. For an event as important as a wedding, you want to eliminate as many unpredictable variables as possible! We grow them annually across the state, with results varying by location and year.


NDSU Agriculture Communication

Source:Ron Smith, (701) 231-8161, ron.smith@ndsu.edu
Editor:Rich Mattern, (701) 231-6136, richard.mattern@ndsu.edu
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