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Hortiscope

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

By Ronald C. Smith, Horticulturist

NDSU Extension Service

Q: When you were on the Prairie Pulse show, you talked about wave petunias, some kind of zinnia and another plant that you said bloomed all summer long and you liked the plant as an annual. The name sounded like narcissus or something. Would you be able to recall? I'm looking for annuals that would do very well in patio pots on the west side of the house with no shade. Thank you for your interesting talk. (e-mail reference)

A: I might have thrown in Echinacea, which is a perennial that loves full sun and heat. It is a prairie native that attracts butterflies. Annuals, such as portulaca and vinca, are champions with full sun and heat. They also are prolific bloomers. A very showy flower that you might consider is the Indian summer rudbeckia. Thank you for the nice compliment about the presentation!

Q: I am from Fargo, but now live in the St. Cloud area. I bought a home that was built in 2003. The developers did a great job of keeping 14 white oaks in the yard. Most of the trees are 60 to 80 feet tall. There is one tree in the front yard that has a huge canopy, but looks to be mostly dead. It is fairly close to the house and the sidewalk is less than 4 feet from the trunk. I have had several landscape professionals stop by to give me quotes on trimming the trees. Only one has said that the front yard tree is probably gone. He sounded the most knowledgeable, but I want to do everything I can to save this tree. There looks to be some buds forming near the top. Is there anything I can do in the way of fertilizer or anything else for this tree? I would rather not top it. Any help would be much appreciated. (Rogers, Minn.)

A: You need to talk to an International Society of Arboriculture certified arborist in your area. The Ludivig Tree Service is in your area and can be reached at (320) 267-6629. Never accept any work from an individual who says he will "top" the tree. All that does is create a huge Frankenstein-looking tree and eventually leads to the tree's death. The certified arborist should be able to tell you what, if anything, can be done to save the tree or whether you should have it removed to keep it from becoming a hazard.

Q: How do you control slugs in a garden? I have tried beer traps with some success and the product called sluggetta, but I don't like using chemicals in my garden. Are there other options? If I have to use chemicals, what are they and are they considered safe? (e-mail reference)

A: There are many ways to fight slug invasions. A series of shallow dishes filled with beer or decaying fruit, such as banana peels, are good. Set the dishes at ground level so the slugs are not challenged to get in them. This is probably the most effective. With the beer, the slugs drown and have a happy death. With the decaying fruit, they think they have found slug heaven and congregate in large numbers. The beer trap kills them, while the fruit just traps them. Diatomaceous earth spread in 1/2-inch bands around plants will do them in by lacerating their soft body tissue. Forget crushed eggshells because the idea doesn't work despite the many references to the contrary. One would think it should work, but it doesn't, so don't waste your time. Wood ash and hydrated lime (handle with gloves and don't inhale!) spread around garden plants will discourage slug activity. Both materials cause dehydration and burning sensations on their soft tissue. Finally, the best way to control them is to alter their environment. Slugs like cool, dark and moist locations. Prune, replant or do whatever you can to dry and heat up the location where they seem to be most pesky. Persistence is necessary to win the battle with slugs because one slug can produce young without fertilization.

Q: New growth on my ash tree was severely interrupted by freezing temperatures. Is there any reason for concern? Can anything be done to enhance recovery? (e-mail reference)

A: Not much you can do except being patient. Mother Nature, in her infinite wisdom, anticipated such capricious action by the weather and the tree has reserves that will allow it to bud later in the season. The canopy will not be as dense, but the tree will survive.

Q: We built our home in a wooded area two years ago. I was careful to save a dogwood tree in the front yard. The tree seems to be doing well. It leafs out every year and it gets the green berry flower center, but it isn't producing the white, flowery leaves around this center berry/flower. We have a dogwood identical to it down the street that is flowering properly. Is there anything I can do to help it flower? I am worried that maybe we cleared too many trees around it. (e-mail reference)

A: The dogwood "flower" that everyone refers to is actually a series of modified leaves known as bracts. They color up about the same as poinsettia "flowers" do. The actual flower is in the center of these colorful bracts on both species. While long nights initiate flowering and bract coloring with poinsettias, I'm not sure what turns the bracts white on dogwoods. I would encourage you to be patient because it should recover.

Q: I'm 15 and recently became interested in keeping houseplants. My mother gave me a group of four plants in a small pot. They seemed to be outgrowing the pot, so I decided to repot. It's been about five days and the plants seem to be doing well, except for one. I'm not sure what kind of plant it is (I would be grateful if you could identify it from the pictures), but shortly after repotting, all of the leaves and stems went limp and the plant seems weak. Some of the other plants are slightly limp as well, but nowhere near as much as this one. I watered it slightly after repotting and have kept the soil slightly moist. I used a basic potting mix with slow-release fertilizer. I also should mention that many of the leaves were bent toward the light (it's a climber and was resting on my dresser, so the stalks bent toward the window), but when I repotted, I turned them so they were facing down. My thought was that the leaves would move to face the light again. Could this hurt the plant? Is this a normal reaction to repotting or is there something else wrong? (e-mail reference)

A: Some shock is normal when moving plants from a very crowded potting situation, but a plant going totally limp is not normal and is beyond any hope of recovery. My best guess from the photos is that the plant is some sort of Swedish ivy, but I wouldn't bet the farm on it. You might try cutting off the limp leaves and then keep the root system and crown hydrated to see if some new growth will emerge in the next few weeks. I doubt it will, but you never know unless you try.

Q: My jade plant is in need of pruning and repotting to a larger pot. It is a very healthy, strong plant, but I'm wondering what I should do first. I would like to prune first because transplanting would be much easier with some of the growth removed. Is it too traumatic to do both at the same time? Should I do one and then wait a few weeks to do the other? Also, I always have propagated my jade plants in water with a lot of success. I actually have five cuttings rooting that are growing leaves underwater! I want to try rooting the new cuttings in a sand mixture (particularly with the large cuttings from this pruning), but I'm nervous. Should I stick with what has been working or do you think I will have more success with sand? What is the difference? (e-mail reference)

A: Congratulations on your success with jade! I usually get only complaints about this very majestic and easily grown plant. You can root the cuttings and leaves in a moist sand medium. The difference is more air for root development and a better chance of survival when transplanting. It seems that roots that develop in water don't take as well to being moved to potting soil as those that are rooted in sand or a sand/peat combination. Go ahead and cut your jade back before repotting because it actually will help the plant get re-established faster.

Q: What is the best way to destroy the diseased branches that have been pruned from a black knot chokecherry tree? (e-mail reference)

A: The choice is up to you, depending on where you live. Cities usually pick up cut branches and limbs. In the country, burn the branches.

Q: I have a Satsuma plum tree and have purchased a Santa Rosa tree to pollinate it with. It was a bare-root tree, so they don't want to send it home with me until May 10. My other tree is blooming now and I can't find a pollinator around to clip a branch from. The tree has more than 200 blossoms and I don't want to lose this fruit. Do you have any ideas? Also, I have three wild plum volunteers. They have beautiful blossoms every year, but no fruit. What could be the reason? (e-mail reference)

A: Why are they waiting until May 10 to give it to you? What is wrong with planting a bare-root tree? It is done all the time, so that line of thinking just doesn't make sense to me. Where is it you live? What good is a pollinator if it arrives more than two weeks after the cultivar is finished blooming? Unless there is a pollinator nearby and a lot of bee activity, you are out of luck. With your wild plums, lack of fruit set could be due to windy, rainy or cold conditions. It also could be a lack of bee activity at the time the pollen is viable. If these wild plums are self-sterile and from the same parent, they won't set fruit.

Q: I am enclosing some photos as well as branch samples from the evergreens in our yard. Last fall I noticed some needle discoloration, so I called on the Extension agent here. He felt the problem was a fungus and said I could wait until spring to spray or do it in the fall. I sprayed them last fall with a fungicide. He also said I could trim back the diseased parts, but thought it best to see what happens by spring. The agent checked for excessive water problems and felt that was not the problem. We have our own well with brown water and an underground irrigation system. Watering had been set for 4 a.m. twice a week. This gave the trees an inch of water a week. Now the trees look as though they are drying. The only green that is left is quite close to the center. There are shoots on them from fall that still have not begun to open, but the branches are pliable and not dried to the point where they easily break off. I have a feeling that the trees are suffering from spray drift because we are close to a road that was sprayed for weeds late last summer. Please tell me what can be done to save these trees. Thank you for your help. (Mott, N.D.)

A: The buds on the sample were dead and the foliage appeared to have salt burn symptoms. Based on this and the other information you provided, it appears the trees are in an irreversible decline from herbicide spray drift and salt spray from winter deicing activities. I suggest removing the trees. If you replant, move the planting site further into your property, so the trees are away from weed and salt spray drift. After the replanting, I suggest a protective spray with an antidesiccant. While this slows growth a little, it provides protection from aerial drifting of some herbicides and salt spray.

Q: I have two weigela bushes that look as though frost got to them. Will they come back? What should I do to help them? (e-mail reference)

A: Best thing to do is wait to see what new growth comes out and then prune out everything else.

Q: I have 12 protected willow trees on a plot of land that I own. I need to build a house on the land so that I can sell the plot. One tree is in the way of me getting permission. The tree in question is a bit battered and worn. What is the best way to kill the tree without cutting it down? You mentioned that there are ways. Could you give me the name of the best products, even if they are not legal? Here in England, once the tree is dead it can be removed and it doesn’t matter how it died. Thank you for your time. (England)

A: You can use chemicals or go the nonchemical way. The decision as to which method to use is yours to make. A nonchemical way is girdling. If the trees in England have not begun leafing out or are just starting to, now is the perfect time to girdle a tree. Remove the bark in a circle around the base of the tree in a band that is at least 2 to 3 inches wide. Be sure the cambium (green tissue that will be evident when the bark is removed) is completely disrupted by scraping it down to the xylem (wood) of the tree. This action disrupts the phloem, which is responsible for the movement of the nutrients to the top of the tree. This action starves the tree to death. The tree will still leaf out this spring, but just barely. If the tree is in full leaf, it still will die, but it will take longer. It should be completely dead by next spring. The chemical method is to use an herbicide that is labeled for broadleaf woody plants and inject it into the base of the tree. You should get someone who is licensed to do this because I don't know what is considered a restricted-use pesticide in England. Willows don't give up easily, so suckering from the root system probably will happen. Good luck!

Q: I live in Georgia. I have a river birch planted within 10 feet of my house. It is a healthy tree, but one of the trunks on the tree was growing too close to the house. It did some minor shingle damage and completely hung over the roof of the house. I decided to have that trunk removed. Should I cut the stump down to the ground or let it be above the ground? The other trunks are at considerable angles away from the house. Could there be an imbalance, weightwise, for the tree as a result of removing one of the trunks? What should I do to ensure the survival of the other two healthy trunks? Thank you. (Athens, Ga.)

A: Cut the stump as low to the ground as possible for aesthetic purposes. Don't worry about the tree falling over because the roots are evenly distributed and give good support. On birch trees, the roots "pancake" out more than developing deep tap roots, so you should be OK, unless a hurricane reaches that far inland! As for the remaining two trunks, I would hire an International Society of Arboriculture certified arborist to inspect and care for the tree every spring. I have a 22-year-old cut leaf weeping birch in my front yard. Every year I have a certified arborist trim out any dead wood (I'm too old to do any tree climbing anymore!) and treat for borers. A company with an arborist in your area is at http://www.treeco.biz/.


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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