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Hortiscope

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

By Ron Smith, Horticulturist

NDSU Extension Service

Q: We hope you can tell us what is wrong with our maple tree. The tree didn't produce any whirlybird seeds this spring. It did produce the red stuff that usually falls all over our driveway and sidewalk, but it dried and shriveled on the tree. The new branches the tree produced are falling off. Other than one spot on the north side of the tree, all the branches are bare, except the very tips. It almost looks like a miniature maple tree because all the new leaves at the tips of the branches are small. The weather hasn't changed and we don't believe there are any insects. Our winter was long, but otherwise typical for Pennsylvania. It is a very large and beautiful tree, so we'd hate to lose it. (Erie, Pa.)

A: A virus or systemic wilt could be causing this unusual growth. I cannot make a diagnostic analysis from here, but I can point you in the right direction. Contact an International Society of Arboriculture certified arborist in your area. Go to http://www.isa-arbor.com/findArborist/verifyArbByLoc.aspx on the Web to contact one of the individuals listed there. Explain your problem as you have to me so that person will know if the tree can be saved or if it needs to be removed. From what you have told me, it doesn't sound like it is long for this world, but I hope I'm wrong.

Q: I live in Schaumburg, which is northwest of Chicago. I have a huge cottonwood in the backyard. It usually covers us with cotton by this time of year, but this year the tree has produced none. It looks like it is the same story with a cottonwood across the creek from us, which is about 50 feet away. Is the tree sick? (e-mail reference)

A: I doubt it, but whatever the problem is, let's hope it stays that way in future years!

Q: I have some friends who have hydrangea bushes. The bushes came with the home they bought in 2001. We aren't sure what kind they are, but they get lots of beautiful, blue blooms. Sadly, because of construction, several of these bushes will need new homes. I plan to bring two of them to my house. What is the best way to transplant them now because we can't wait until fall? How big are the roots of these bushes? (e-mail reference)

A: The roots would be quite extensive right now. Track the weather in your area. When a cool, cloudy or rainy day is predicted, go out and cut them back to a manageable size. Dig out the plants with as much manageable root system as possible. Wrap the roots in soaked burlap and transport and plant at the new location as soon as possible. Plant the bushes at the same depth and, if possible, in the same type of location. Water in well with a solution of Miracle-Gro fertilizer and hope for the best!

Q: Our squash plants look extremely healthy. The plants have lots of blossoms, but no fruit. Do we need to help Mother Nature with pollination? Also, our pepper plants look sick. They have wilted leaves that do not recover after watering and do not have fruit. (e-mail reference)

A: Give Mother Nature a hand with pollination. As for your pepper plants, they probably have root rot because they do not respond to watering. I'd suggest ripping them out.

Q: I have six emerald green arborvitaes separating my house from my neighbor's. They are experiencing a type of foliage decay on the bottom quarter. I've had fungus problems with other bushes in my yard this year, so I'm curious if arborvitae can experience fungus or disease problems. The foliage is taking on a brown/green appearance. It's not the normal browning of the foliage that I've experienced in the past. I sprayed them with a fungicide today. Should I try to fertilize them and see if they make it through? (e-mail reference)

A: I am guessing that you have an automatic lawn sprinkler system that is impacting the shrubs. If not, then it is likely due to very heavy vegetation on your property and surrounding area that is creating an ideal environment for fungal development. Continue with your fungicide applications every 10 to 14 days. It will not cure what has taken place, but should keep it from spreading. If the sprinkler system is the culprit, then get a contractor to realign your sprinkler heads so they spray away from your woody plants.

Q: We have an apple tree that was damaged a few years ago. The main trunk was split about 6 to 7 inches deep. We had a plastic tie around it and it seemed to be growing back together. This past winter a hemlock tree fell and hit the apple tree, so the split opened up again. My brother-in-law said that they sell a grafting solution that can be poured into the opening to seal it. I went to the local farm supply store and the man knew what I was talking about, but didn't carry it anymore. Any ideas where I can buy this stuff? (e-mail reference)

A: What your brother-in-law is talking about is Cabot's tree paint. While it seals up the wounds, it also inhibits the wound healing process, so you are really better off putting the splits back together using bolts and/or cables.

Q: I'm sending some pictures of a maple tree in my front yard. It has vertical cracks in the trunk and some fungus growing. Could you please tell me what it is and how to treat it? (e-mail reference)

A: You probably are not going to like this advice. The mushrooms growing along the many splits in the trunk indicate that internal rot has set in. After looking at the crown of the tree, about 25 percent to 30 percent is dead or in decline. I suggest replacing the tree. To prevent this from happening in the future, wrap the trunk of the tree to the first lower branches before winter arrives and keep it wrapped until the tree leafs out in the spring. Don't overwater or overfertilize. Once the tree develops a corky trunk in a few years, the wrapping no longer will be needed. Your problem is caused by the winter sun hitting the south and west sides of the trees and getting the tissue active from the rise in temperature. When the sun goes down, the tissue suddenly freezes again, which causes expansion and ruptures the cell tissue, resulting in the damage you are seeing on the tree. The problem is inappropriately called "sunscald." It should be called "frostbite."

Q: I have a spider plant that has brown/black specks on the leaves that look like a pest's droppings. There are blotches on the leaves that look like they are almost eaten through. Some of the leaves have fallen off. Is this caterpillar damage? I have looked, but do not see any. What can I do to save my plant? (e-mail reference)

A: It is hard to tell what caused the damage. Based on what you have told me, I would suggest making a solution of insecticidal soap. Dip the plant into the solution up to edge of the pot. Wear dishwashing gloves to protect your hands. It is not toxic, but could cause the skin on your hands to get very dry. If you are unable to dip the plant, spray the plant with the solution as completely as possible.

Q: We have a cottonless cottonwood in our backyard that was planted 24 years ago. It seems to be a healthy tree. However, for the last three or four years, high winds have brought down hundreds of twigs. Is this normal during mild or severe drought years? Would deep watering help? We had an underground sprinkler system installed two years ago, but it hasn't seemed to make any difference. (e-mail reference)

A: Unfortunately, this is a strong characteristic of the species. Watering wouldn't do much good. With this species and willows, twig collection is a way of life.

Q: Could you possibly tell me why my weigela has not flowered the past few years? It used to flower every spring. The plant is on the west side of my house in Kansas City. Other than not flowering, the plant looks very healthy. (e-mail reference)

A: Lack of flowering usually is tied to poor timing on the part of the plant coming out of dormancy and the environmental conditions at the time. As plants come out of dormancy, the most vulnerable parts of the plant are the flower buds. An uncharacteristic cold snap could kill the flowers, but not affect the leaf bud tissue, which has a higher hardiness level than the flowers. Another possible reason could be too much nitrogen fertilizer reaching the plant, which would keep it in the vegetative stage of growth. This often happens when lawn fertilizer makes its way into the woody plants surrounding the lawn area.

Q: We planted a willow tree about two weeks ago in a 5-foot hole. The hole was twice the depth of the pot it came in. The tree seems to be OK, except the leaves are turning yellow. From what I have read, they need a lot of water. However, are we overwatering it? (New Rockford, N.D.)

A: I doubt that you are overwatering because willows thrive in wet soil environments. Perhaps it is planting shock or a response to high temperatures. It should stabilize and grow for you.

Q: I have a red pine that has had its bark gnawed or clawed off at the base. It looks to me as if the critter was after the sap. I suspect the woodchuck I occasionally see, but others have guessed beaver or porcupine. Last fall, a chunk was missing on the side that is away from the house. However, the tree made it through the winter with flying colors. However, the critter has become bolder and girdled the whole base of the tree. There are 20 other pines in this stand, so it'd be a lot of work to put chicken wire around all the trees. However, I did buy some chicken wire and am prepared to wrap the trees. Is there anything I can do to save this tree? It's by the lake, so it's very pretty in that location. A friend suggested latex paint. Have you ever heard of this remedy? I'm wondering if the paint might kill the tree. This happened a few weeks ago, but the tree seems fine. (Dent, Minn.)

A: If the tree is girdled, then it is considered dead. It will retain the green foliage for the balance of the year, but will be toast next spring. I suggest tight hardware cloth around the rest of the trees. I'm afraid the chicken wire might not be sturdy enough. No paint of any kind is going to help when the tree is girdled. In fact, it won't help with anything.

Q: My zucchini plants are doing great this summer, but one is crawling with ants. The small, black ants are thick inside the blossoms. Will they hurt the plant? If so, what can I do? (Denver, Colo.)

A: The ants have found the nectar that the bees love. As long as they are not destroying the flower, I don't think they will hurt the plant. If the flowers are not setting fruit, then they need to be dealt with as soon as possible so that you can enjoy the zucchini fruits! You don't want to be the first gardener in history who planted a zucchini and didn't get any fruit!

Q: My hollyhocks are getting holes in the leaves. Do you know what causes this and is there a way to get rid of the problem using products that I may have around the house? (e-mail reference)

A: Hollyhocks are subject to many insects and this one could be caused by a leaf skeltonizer, which probably is gone from the scene by now. I would advise using a systemic insecticide, such as an Ortho product, that would be present in the plant when the attacking insects decide to make your plants a meal, which would be their last meal.


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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