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Hortiscope

Ron Smith answers reader's questions about the world of plants, trees and gardens.

By Ron Smith, Horticulturist

NDSU Extension Service

Q: We are on the borderline between zone 3 and 4. We just purchased sungold and moongold apricot trees from a local nursery. The trees are potted, but don't appear to have been pruned. I read some information from the North Dakota State University Extension Service that recommended planting these trees with the bud union 4 inches below ground. I am assuming this is for cold, winter climates such as ours. Is this correct? Also, can you give us some advice on pruning these trees? What about proper location? We also purchased toka and superior plum trees. Will the superior do OK in our hardiness zone? (Somerset, Wis.)

A: That recommendation was made decades ago. Because we live in zone 3 here in North Dakota, we are going to stick to it until we have proof that normal planting is acceptable. In your location, you shouldn't do that because of the milder winters. Don't prune them for the first year or two. They need all the leaf surface area possible to build a good root system. For cultural information, download this publication at http://www.ag.ndsu.edu/pubs/plantsci/hortcrop/h327w.htm. Both plum varieties should do well in your location.

Q: We planted three autumn blaze maples a few years ago. This spring, all three budded out, but one did not develop leaves. The little buds are still green, but there has not been any change in it for about two weeks. Meanwhile, the others are fully leafed out and beautiful. Could it have died suddenly? (e-mail reference)

A: Something did it in. It could be a root rot organism because what you describe is somewhat symptomatic of that problem or the stem of the tree was girdled either mechanically or by some nibbling rodents.

Q: Someone told me you might be able to provide me with information on a grapevine (valiant) that I purchased last year. The vine produced a lot of grapes last summer, but they were bitter. Not even the birds were interested in eating them! Is there anything special I need to do to the soil to make the grapes edible? Also, this past winter, a few voles took residence in our yard. I can't seem to get rid of them no matter what product I use. Now the voles are eating some of my perennials and multiplying happily. As much as I hate to do it, I need to exterminate them. What type of poison do I need to use to get rid of them? I have not seen any poison just for voles. (e-mail reference)

A: I have no explanation for the bitter taste of the grapes. I've had a valiant vine growing in my yard for years and it is always loaded with dark, juicy, sweet grapes. Give it one more year and see what happens. Harvest the grapes after the first frost. If they are still bitter, rip the vine out and get another one. You probably got a wild vagabond vine by mistake. Voles are cute rodents you don't want to put up with. In your situation, I would encourage you to call Johnson Pest Control in West Fargo. I the company has the most competent folks in town to do the nasty jobs the rest of us get bogged down in and fail at miserably! They will have something that will take care of the problem for you.

Q: We planted four poplar trees when we had our house built in 1998. The trees are amazing, but something happened this year that hasn't in the past. Our yard is filled with a cottonlike substance. It is very frustrating for me and our neighbors. I noticed the substance is coming from the top of the trees. Is something weird happening to our trees? Is this something that will happen every year? Everyone thinks there is a cottonwood tree in the neighborhood. They haven't figured out that it's from my poplar trees. (e-mail reference)

A: You got one of those cotton-bearing, female poplars. And yes, you can look forward to this every year about this time. The unfortunate thing is that there is no way of telling male from female trees when they are young, so it often catches the homeowner by surprise years later. The only sure way to keep from getting a cotton producer is to purchase male-cloned trees. However, you are depending on the integrity of the grower.

Q: I am an avid reader of Hortiscope on the Web, so I am hoping you can help me. In late 2006, I purchased four trees from a local (Hudson, Wis.) tree service. The trees were planted in October 2006. Two of the maples are emerald queens. The other two are a Norway and an autumn blaze maple. For the second consecutive year, the leaves of the Norway emerged purplish/red in color. The first year I thought it odd. Now, after doing research, I wonder if they delivered a Deborah maple instead of an emerald queen. Have you ever known an emerald queen to have purplish/red leaves in the spring? My research indicates that is a characteristic of the Deborah. I have a similar question on what I thought was the autumn blaze. There are a bunch of seeds on this tree similar to what some would call helicopters. Is it normal or possible for an autumn blaze to have seeds? I have had three others for years, but they never had seeds. (e-mail reference)

A: Thank you for being a faithful reader of Hortiscope. It sounds like you got some mislabeled trees. Autumn blaze is a hybrid between a silver and red maple. As far as I know, it is considered seedless. The Norway also probably was mislabeled. It can happen in the frenetic life of growing and labeling trees in a wholesale nursery.

Q: I've got something invading my lawn. It's got small, green leaves with small, lavender flowers that have a pungent, obnoxious smell. It is spreading like crazy. I'd like to get rid of the stuff, but I'm afraid that whatever would kill it also would kill the grass. It seems impervious to regular lawn weed spray. I'm prepared for the worst and realize vegetation killer may be the only answer. What do you suggest? (Fargo, N.D.)

A: Go for Trimec. If that doesn't do the trick, nothing will! The weed sounds like wild violet, which is a tough cookie to kill.

Q: A couple of years ago, I cut down a flowering crab tree. Even though I removed as much of the trunk and roots as I could, I battled the suckers that continued to try to grow for many months. I now am faced with removing another large crab tree. How long should I wait before planting a new tree in the same spot? I am concerned about the remnants of the old tree trying to survive. (e-mail reference)

A: Treat the sucker growth like broadleaf weeds, such as dandelions. Hit the suckers with the herbicide that controls this ubiquitous flower. You will win eventually, I promise. There is no hard and fast rule for waiting until replanting. Generally, three years comes to mind. As long as the old tree did not have a root disease problem, you probably could get away with a shorter time to wait.

Q: Our subdivision used to be a farmer's barn area. Supposedly, it was a compost area for manure. We have had lots of questions about what fertilizer is good for the average arborvitae. We have been told that 16-16-16 is good, but how much per plant? We have amended our soil many times before we had our soil tested. We lose lots of plants because something isn't right. (Hillsboro, Ore.)

A: The soil test should have revealed if anything was wrong. Usually, in old compost sites it is the soluble salts that are too high. Generally, arborvitaes and other trees don't need fertilizer when planted and seldom need it later. Usually, a hit of Miracle-Gro to make the owner feel good is all that is needed and it doesn't hurt the plants. One other thing to consider is that many farm fields have herbicide residue that remains toxic to certain classes of plants. The residue would not show up in a standard soil test and testing for it in a lab is very expensive. A suggestion is to go to a local nursery and purchase a tomato plant and a single corn plant if one is available. Plant the tomato and corn in the area where you are having the problem. One or the other probably will die, but it will give you a hint about the herbicide that is in the soil. If they both die, then forget it and haul in new soil.

Q: I am getting a white, powderlike material on the leaves of two crepe myrtles. I sprayed a fungicide on the plants, but it didn’t seem to do any good and the stuff seems to be spreading. What can I do? (e-mail reference)

A: Get a fungicide that is specific for controlling powdery mildew and spray the new leaves as they unfold. Generally, this fungus is not lethal to the plant, but it does weaken it somewhat, so it should be controlled as much as possible.

Q: My husband and I moved into a new subdivision last October. There is one road with about 12 houses in this subdivision thus far. Each of these houses has a maple tree planted in the front yard. When we looked and put an offer on the house, all of these trees had leaves and were doing great. I believe they are the maples that are a really pretty reddish-orange in the fall. Since spring, we noticed buds on a lot of the other trees. It even looked like ours had buds at the top. However, up to this point, our tree and some of the others do not have leaves on the top. Ours has no leaves, but did send out buds on the trunk of the tree. Some of the other trees only have leaves coming out on the bottom branches of the tree. We eventually bought another tree to replace the maple and had someone plant it for us. They informed us that the maple was still alive even though it had produced no leaves. We dug the maple up anyway and transplanted it to our backyard to see if we would get different results. This was about a month ago. We thought whoever planted the trees may have had too much mulch around the tree, so it was not getting sufficient water. So far, the tree still is not leafing out. It looks like it has buds on top and is budding out on the trunk. We never have seen a tree do this. Can you help us out? Would it be better to dig the tree up and dispose of it or is there something else we can do? (e-mail reference)

A: This sounds like an environmental problem with all of the trees. A cold snap must have hit the trees sometime this winter or spring. While the tree is basically alive, it is not thriving and probably never will. Since it is in the backyard and not a centerpiece for the front of your property, you can leave it there for the remainder of the summer. Give it sensible care to see if it pulls out of its funk. If you have better things to do with your time, pull it out and get rid of it.

Q: I found lots of aphids on my pepper plant (I assume that's what they are). I wiped them off and sprayed the oil/soap/water solution you recommended. I also found very tiny white worms that apparently like to chew the blossoms off where the stem meets the plant. They look like microscopic caterpillars. We have lost five blossoms in three days. I have found three of the tiny worms and removed them. Can you tell me what they are and how to get rid of them? (e-mail reference)

A: I don't know what they are. There are too many caterpillar insect species that could be doing the job! Believe it or not, try a hot pepper spray on your pepper plants to see if that discourages them from eating. If they can tolerate that potent stuff, they are pretty tough cookies! That would at least keep you from using a chemical in your garden that is not cleared for organic purposes.

Q: My grandparents had Italian plum trees. Is a Stanley plum the same thing? (e-mail reference)

A: I don't believe so. While both are plums, one is considered a prune rather than a plum. I’ve been told that the only difference between a plum and a prune is the size of the fruit.

Q: Reading your answers on the hibiscus Web page made me feel almost guilty about hating the hibiscus plant that is almost covering my front flower bed. I just want mine to not completely cover my windows! What is the best way to trim a hibiscus? This plant has grown very tall and spills over the side of the flower bed. I don’t want to get rid of it all, but I would like to find some way of taming it. (e-mail reference)

A: Pruning it after the leaves have fully elongated to their normal size will slow the rate of growth. Do not leave stubs and cut it back to just above a leaf bud node or adjacent branch.

Q: We have three October glory maple trees. The trees were planted three or four years ago and have done very well. This year, two of the trees are doing well, but one of the trees appears to be dead. I thought the tree was not going to show any signs of life this spring. However, in the last two weeks, some leaves have begun to grow from the trunk below all of the previously existing branches. It appears that the branches are dried up above this new growth. The tree seemed to weather the exceptional drought we had last year and did not show any signs of damage last fall. Do you have any suggestions? Should we prune the tree or is it going to die? (e-mail reference)

A: A common mistake made by beginning and professional gardeners alike is the assumption that drought stress is seen immediately. Actually, a tree or shrub may appear to weather a drought quite well, but, in reality, the stress of the drought is the same as a loaded gun. The slightest other man-made or environmental stresses, such as soil compaction or an out-of-season cold snap, could send it over the edge. Drought-stressed trees also are vulnerable to insect attack by bark beetles, borers and leaf eaters. I suggest replacing the tree. The top part probably is dead from either a canker or one of the insect problems mentioned earlier.

Q: I have three red maples in my yard. They are more than 10 years old. I noticed the seed on one of the trees is very tiny compared with the other two trees. The seeds hang on the tree with delicate, umbrella-shaped, thin stems. The seeds are the same helicopter shape and show the same red and tan as the other seeds. The leaves are more like a lace leaf than the others. Is this a different variety? (e-mail reference)

A: It sounds like you have a different cultivar of maple. Just enjoy it and don't worry!

Q: Are weeping cherries adversely affected by walnut trees? Ours seems to be doing poorly and it is close to a walnut tree. On the lists I've seen, weeping cherries are not mentioned. (e-mail reference)

A: The walnut tree is bound to have an effect of some sort. Its impact is greatest on herbaceous plants, followed by various woody plants. Walnut trees are very jealous. Once they stake out a territory, they are intolerant of any other plant encroachment.

Q: Not long ago, I separated a crowded peace lily into different parts. I potted the plants in larger pots. I hope you know what kind of plant I mean because I don’t know the official name. However, it is quite common and seems to be available almost anywhere. It has a white bloom that looks a little like a calla lily. The plants I repotted are not doing well. They put out new leaves, but the leaves all start turning brown at the tip and then continue to turn brown and brittle until the whole leaf is dead. The few blooms that have appeared also start turning brown at the tip and die. I have tried to stop fertilizing (I usually fertilize all my houseplants with Shultz liquid as directed on the package). I have tried to change the amount of sun they get and hold back on water. Now the plants are sending out new shoots from the base, but the leaves on the new shoots also are turning brown at the tip. Can I save them or should I dump them? (e-mail reference)

A: I don't know what you can do to save the plants. It sounds like they may be getting too much water or they may be attempting to go into dormancy. Try allowing them to dry down for a couple of months and then start watering them to see what happens. Otherwise, dump them.

Q: We recently moved into a new home with five wine-colored weigela plants that were never pruned. Last fall, I pruned the oldest one-third of the branches. This year, only half of the branches have leaves. Near the bottom of the shrub, there is new growth. I am not sure how I should handle this. I pruned back the branches that did not have any growth to the point right above where new growth begins. Also, on the branches that did produce leaves, there are leaves on top and then bare wood to the bottom of the plant. Should I prune all the branches back to 3 or 4 inches above the ground? (e-mail reference)

A: Your ideas are good, but the timing is off. Put up with everything you did this summer. Before new growth shows up early next spring, cut it all back except what you see coming from the crown of the plant. Your plants will not produce any flowers that summer, but will be vigorous and healthy and get into flower production the following year.

Q: I am having an awful time trying to get a perennial garden established. The only plants that seem to grow are day lilies and a bleeding heart. I have tried planting lambs ears, gerbera, delphinium and rose bushes. The plants bloom and look nice the first year, but do not grow the following year. Are there some perennials that are more adaptable to our winters? I also am having trouble with iris plants this spring. They look root-bound and there is very little soil on top of them. Did the plants possibly freeze? They are not growing at all. If I thin them out and put soil on top, will they grow again? I thought iris plants were hardy to my area. I read your article in the Sun Country and look forward to your advice. (Fredonia, N.D.)

A: Iris is hardy to your area. However, do you remember Mother's Day weekend when the snow and cold hit? It wiped out a lot of perennials for this year because they had been teased into beginning growth only to be hit with that nasty, wintry blast. It killed a lot of our plants on campus, too, so you are in good company. As to hardy perennials, a list Barb Laschkewitsch, my NDSU colleague, and I put together can be found at http://www.ag.ndsu.edu/pubs/plantsci/landscap/h322w.htm. Your problem may be poorly draining soil. It doesn't kill the plants in the dead of winter. However, in the spring, with temperatures going between freezing and thawing, the cells in the crown rupture as they are beginning to deharden.

Q: I found your Web site to be very useful to learn about working with a raspberry patch that came with a little house I bought in Michigan. This year, sprigs are popping up all over my yard. I have been trying to dig them up, but I can't keep up! If I use Roundup as you suggest, will it travel through the root system into the edible berries? I want to avoid using chemicals as much as possible. (e-mail reference)

A: I would use Roundup to get caught up with the hand digging you are doing. It is worth the effort so you can enjoy those healthful berries this summer and any that you freeze for winter treats!

Q: I am sending this e-mail to ask a question for my mother. For the past few years, she has been having problems growing carrots. They are hairy and do not keep very well. I read on one of your Web sites that this could be a root disease. Is this coming from the seeds that she is buying or is this something that is in the soil? If it is the soil, what can be done? Thanks in advance for your reply. (Lehr, N.D.)

A: This is a gram-negative bacterial disease known as Agrobacterium rhizogenes and usually shows up in sites where carrots are planted in the same field year after year. Home gardeners can overcome this disease by rotating their crops to different locations each planting season. As far as I know, there is nothing that can be added to the soil to prevent this disease. I first came across this disease while at Ohio State. At the time, relatively heavy commercial carrot production was going on. It is unusual to have this problem in a home garden, but now you have the facts as far as I know them.

Q: I have a Concord grapevine that I've pruned back every spring. For the past three years, the grapes have increased in number and quality. Last year we had more than 100 pounds of grapes, but the vine was not as leafy as in the past. Because I appreciate the shade the leaves provide, I decided not to prune this spring. I’m hoping for more leaves and fewer grapes. However, it is late May and the leaf growth is very spotty. Most of the vine is bare. Can my grapevine be dying after being so healthy and vigorous? Let me add that we live in Chicago. We had an exceptionally hard winter. (e-mail reference)

A: Exceptionally hard winters followed by a bumper crop have taken their toll on the vine. I don't think you have anything to worry about as far as survival goes. For this year, I would suggest leaving it alone as far as pruning goes. You might give it some fertilizer to help it out. Miracle-Gro would be sufficient. Also, modify your heavy pruning practices of the past.


NDSU Agriculture Communication

Source:Ron Smith, (701) 231-8161, ronald.smith@ndsu.edu
Editor:Rich Mattern, (701) 231-6136, richard.mattern@ndsu.edu
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Prairie Fare: Prairie Fare: Make Good Use of Leftovers This Holiday Season  (2017-11-16)  Take steps to avoid food waste.  FULL STORY
 
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