September 9, 2004

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: Have you ever heard of a miniature lilac bush? (e-mail reference)

A: Yes, there are miniature lilacs, which are becoming more popular with homeowners each year. The palibin cultivar gets 4-feet tall and 5-feet wide, Tinkerbelle gets 5-feet by 5-feet, Miss Kim, 6-feet by 6 feet, and the littleleaf lilac (S. microphylla) gets just 4-feet by 4-feet. Any good garden center in your locality should have these or others. Cut your oldest canes down to the ground every year, but don’t cut more than a third of the total canes. Remove the seed heads as soon after flowering as possible. All of this should help increase the size of your blooms.

Q: We planted 25 Colorado blue spruce trees and are noticing that when the buds opened, they immediately turned brown. About six trees are the most affected with at least one side of the tree full of brown buds. They also have a yellowish look. We have had soil tests done and they came back fine. The trees are planted in a corner intersecting an alfalfa field and a corn field. We water them from a sand point well. We don't want to use chemicals unless it's absolutely necessary and would really like to use organic or natural methods if possible. Can we prune off the brown buds now or should we wait for fall? Our local nursery said it could be frost damage. Could this be possible? (Parker, S.D.)

A: Your nursery could be right. If the symptoms do not appear to be getting worse, then that is very likely what happened. Examine some of the dead buds to be sure there isn’t borer or other insect damage taking place. If frost did hit the trees, the damage shouldn’t be permanent, but it may add a little character to the trees.

Q: I recently purchased a hydrangea bush and planted it in front of my house. I’m starting to notice that many of the leaves are turning yellow and wilting. However, there does seem to be new growth on the top and I see flower buds starting to form. I did everything the nursery told me to do. We have had a lot of rain recently, so the soil is damp. I am afraid that the whole plant is going to die. I have not fertilized because the instructions with the plant directed me to wait. (e-mail reference)

A: Contact your local nursery and tell them what is happening to your plant. I think the plant will come out of its funk when the rains let up, but it wouldn’t hurt to check with the folks who sold you the plant.

Q: I have a spider plant that I bought at a local nursery a couple of months ago. It is the variety with white on the outside of the leaves. It has started to produce babies, so I would like to detach them and start new plants. My father used to have around 30 spider plants in his house. They were started from one plant. I believe that he used a sugar and water solution. This is the method I would like to use, but I’m not sure if the sugar will benefit the plants. Just for fun, I would also like to use water colored with food dye to get the white on the leaves to change colors. Would that damage the plants? (e-mail reference)

A: Plain water will do, but go for it if you want to emulate your father's methods. You could try both methods to see which one works best. I can't tell you about adding dye to the water because I’ve never tried it, but be adventurous and see what happens with at least one of the plants.

Q: What causes rot spots to form on grapes? We have beautiful bunches of grapes, but they look like they are rotting. (e-mail reference)

A: The grapes probably have black rot fungus, which is caused by certain weather conditions. Spray the unaffected grapes with a Bordeaux mixture to stop the fungus from spreading. Next spring, while the plants are dormant, spray the vines with lime-sulfur to sanitize the plants. Remove and destroy all infected grape clusters.

Q: My daughter planted a pair of cottonwoods on both sides of a horse jump. It was a silly idea, but she did it anyway. The cottonwoods have now almost grown together, rendering the jump unusable. I know that summer isn't the ideal time to prune, but it's not an absolute no-no is it? I was thinking of pruning 35 to 40 percent of the branches and leaves. Is that too much? Do you think painting the wounds with pruning or some kind of paint is necessary? I don't know how inclined they are to getting pests. (e-mail reference)

A: There are better times than others to prune. It all depends on what the objectives are. Removing more than 30 percent of the crown at one time could cause problems. Alex Shigo, a forester of renown, has proven that coating the pruning wounds is not necessary. It has been shown to inhibit the natural compartmentalization that takes place after a pruning wound. His motto was that properly pruned trees don’t need pruning paint, while all the pruning paint in the world won’t make a difference if the trees weren’t properly pruned. Cottonwoods are inclined to get pests such as diseases and insects, so be sure your pruners are clean.

Q: The leaves of my morning glories and marigolds are being eaten by some sort of bug. The only thing I can find is a beautiful looking gold colored bug that looks exactly like a ladybug. How do I get rid of these beautiful bugs? (e-mail reference)

A: Try an insecticidal soap. If that doesn’t work, spray with Sevin. Be sure to spray the underside of the leaves.

Q: We have three poplars in our backyard that are probably over three stories tall. The last two summers we have noticed a decline in the number of leaves. This summer we only have some leaves on the lower branches. We are assuming the trees are dead. A few of our neighbors are also having the same problem. How do we get rid of them if they are dead? Is there a company that will take out the trees? If there is, how much should we expect to pay? (Fargo, N.D.)

A: Unfortunately, poplars dying in our area are very common. There is a competent, honest, qualified individual who has done work for me and others that I can have you contact. His name is James Danielson, owner of Cougar Tree Care. His phone number is (701) 729-7208. The cost of removing the trees depends on where the trees are located, how many hazards are in the way and their size. It would be a good idea to get them removed at your earliest convenience because they may have heart rot, which could result in the tree falling on your house, car or even you on windy days.

Q: I know a homeowner that has onion plants that have a lot of top growth, but are not producing any onions. Is there anything that would reduce the top growth and get the onions to produce? Is all of this top growth due to high levels of nitrogen? (Linton, N.D.)

A: The problem is caused by high levels of nitrogen. There is little to nothing they can do, unless they replant in another area that has not been so highly fertilized and gets plenty of direct sunlight.

Q: A lady brought in a sample of flax from her garden that has rust. The cool conditions and her watering seem to have provided the proper environment. Will the rust spread to the rest of her garden? Should she dig up the rust infested flax now? I don't know if there is any treatment other than resistant varieties. (Hettinger, N.D.)

A: She should dig up the rust infected flax. I don't know what the alternate host is for flax rust, but I doubt it is any of her garden flowers or vegetables.

Q: We bought a condo this past winter with a lovely lilac bush in the backyard. The lilac bush has now gotten so big it's taking up half our yard. How should I trim or thin it out without doing any damage? I really would like to be able to put my grill and picnic table out back. (e-mail reference)

A: Get some long-handled loppers and cut down about a third of the canes as close to the ground as possible. That should clear some space for you. Next spring, borrow someone's chain saw and cut the rest back before the plant comes into leaf. The resulting surge of growth will allow you to shape it to the size you want. You will not get any flowers next year, but that is a small price to pay to be able to grill outdoors!

Q: I planted some apple seeds in a pot some time ago. One of them sprouted and was doing well for the first two weeks. Now the edges of the tiny leaves are starting to turn brown. I don't want to plant it outside because I would like it to grow into a big house plant. Is this possible or do they have to grow outside? (e-mail reference)

A: The darkening of the leaf edges means the container is not draining and the roots are either rotting or beginning to do so under anaerobic conditions. The salts in the water source could also be too high. Use distilled water on alternate waterings.

Q: I planted some wave petunias in a pot on the deck rail. They were doing great, but now they are starting to get a little leggy. I'm not sure how to trim them back. Could this be happening because I was cutting off dead flowers? Can I cut back the whole stem after it gets too long? Should the plant grow new stems from the center? (e-mail reference)

A: Wave petunias getting leggy? It shouldn't be possible because these are spreading, densely flowered plants that grow almost with a vengeance. We have them in containers and hanging baskets all over our campus. All that is done to them is watering and fertilizing on a regular basis. It could be that you don’t have a wave petunia.

Q: I know a lady that is wondering if Robby red and Haroldson apple trees are ok for this temperature zone. She lives in the southwest corner of Emmons County. (e-mail reference)

A: I can’t tell you about the Robby red cultivar because I’ve never heard of it. Haroldson can be planted anywhere in the state.

Q: A producer planted a rose bush some years ago. The first two years it blossomed profusely. In the last two years, the buds have only opened partway. (Beach, N.D.)

A: It could be thrip activity. Look closely at the buds and peel the outer petals back to see if there is any evidence of feeding activity or the dirty bounders themselves. If not, then cut the stem off and check for borer activity. The stem should be hollow and empty, or if you are lucky, hollow with the culprit caught in the act! You know what to do then.

Q: I have a maple tree in my yard and the bottom leaves are already turning red. I have heard that it may be caused by stress. I have two male golden retrievers that use the tree as their fire hydrant. Also, my wife sprayed some grass killer around it, but the instructions said it was safe for trees. Otherwise, everything is pretty normal. (Minneapolis, Minn.)

A: There could be at least half-dozen things causing the tree to go into fall color such as compacted soil, wet and cold soil, root rot, a vascular disease or borers. Any grass killer can have a negative impact on a tree. The tree may have been planted to deep or it may be suffering from air pollution of some kind or spray drift from an adjacent property. Contact an ISA certified arborist to see if there is a way to cure the problem before it is too late.

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. Note to e-mail correspondents: please identify your location (city and state) for most accurate recommendations.

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

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