August 8, 2002

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: This is probably very elementary, but can you tell me if the "old wives tale" about leaving cucumbers on the plant until they turn yellow make the plant quit bearing any more vegetables? Will they no longer produce? (Bismarck, N.D.)

A: That is one tale that has some truth to it. Fruit production will slow and stop if it is not picked on a regular basis. The plant will read that as completing it's life cycle, having set the fruit with the seed within and allowing it to mature. So if you want your garden to continue productivity, keep picking the young tender fruits as they develop and you will be able to extend the harvest beyond just a single picking.

Q: I have a question concerning potato plants that are very tall and lush with lots of blossoms but few potatoes. Idaho red potatoes were planted in late May. They are now 3 to 3 1/2 feet tall and in full bloom. After digging 12 hills, there were only three to four small potatoes found. Is there a way to force a potato's energy into growing the potato instead of the plant itself? (Dickinson, N.D.)

A: It sounds like the plants have had too generous an application of nitrogen-containing fertilizer. Accept what comes this year, and try not to be so generous next year.

Q: I have a Japanese maple tree about 2 years old. I had contractors that did some waterproofing work around the brick work of the tree. The leaves are starting to brown and dry up. The contractors must have spilled some of the waterproofing material in the soil and the tree is drying. What should I do? (E-mail reference)

A: Without knowing what the material is, I suggest a generous watering of the tree, several times and hope that leaches the toxin beyond the root zone. I would certainly let the contractor know of your displeasure, and see if you cannot get some kind of compensation should it need replacing. They are beautiful trees that shouldn't be wasted like that.

Q: A client is growing leaf lettuce in an old tub with no drainage. They didn't want to drill holes in the old tub. The leaf lettuce has turned out okay, but moss has been growing on the soil in the tub. The’re wondering if the lettuce is going to be safe to eat with the moss there. I would think it would be safe, but what do you think? (Cando, N.D.)

A: Should be no problem. But as always, wash fresh produce before consuming it, no matter where or how it is grown, to be on the safe side.

Q: I've been having problems with plants in my yard. I have a weeping birch tree. Most of the leaves on the tree are yellow, then they curl up and turn brown, along with a mountain ash and a plum tree, I've had branches on the trees that die from this. I also have annual bedding plants that are doing the same. They are a nice dark green when I transplant them, and about a month ago they started to turn yellow and die. I sent a soil sample away, and the report said I needed more nitrogen. I've been fertilizing with a liquid fertilizer 30-10-10, about once a week. It seems to be holding the tree leaves from turning brown; some annual plants are at a standstill but still yellow. I've also tried spraying iron on the leaves, but nothing seems to be working. Do you have any solutions to my problems. (E-mail reference)

A: It sounds like you have a problem beyond nutrition. The soil may have been contaminated with a sterilant or pesticide that is causing the problems. It is unusual for such a wide species range to be affected this way without it being a soil problem of this sort.

Q: How do I get a start off my neighbor's hydrangea bush? (E-mail reference)

A: Ask first, of course. Then take softwood cuttings from the May, June, or July growth, and root in a 50/50 sand/peat mix, under mist.

Q: We have a 25-year old conttonwood tree by our house that seems to be in trouble. The trunk forks about 5 feet off the ground, and the bark is split and weeps a clear liquid. The bark is getting rotten. From the side it appears that the trunk is bulged where the split is. It grows in very sandy soil that is about 100 feet deep. No special care has been given to it. Now there is some leaf drop. There are many cottonwood trees below the house near our lake that my husband's grandfather planted when he homesteaded here around 1904. I love this tree and the branches are within reach of our second story deck so we hang bird feeders in it. If there is any danger that it is dying we would have to cut it down as it could fall on our house. A friend suggested that we drill a hole through the trunk below the fork and insert a long bolt with washers on each end to pull it together. (Wildrose, N.D.)

A: Your friend gave you good advice, but that is not something you should do. It should be carried out by an arborist who knows what is going on and can perhaps further advise you on what else needs to be done to preserve your tree.

Q: I have a cottonless cottonwood that appears very hardy, but it has some white foam coming from the trunk. What is it and how can I get rid of it? (E-mail reference)

A: I think the "white foam" you are referring to is in reality evidence of internal wood decay, and what you are seeing are the fruiting bodies. These growths are an indication of advanced decay and are known as conks. I would advise contacting a local arborist to see if a determination can be made as to the safety of the tree.

Q: I planted some peony (root only) this spring on the south side of the garage. Most came up right away and are about 4 or 5 inches tall. They haven't grown much in the past few weeks, and now the leaves on some of the plants are beginning to turn yellow. I can't see any rings on the leaves, they are just turning yellow toward the outside of the leaves. What could be causing this? (Aberdeen, S.D.)

A: A common mistake is to plant the peony roots too deep, so that would be my best guess at this point. Try pulling the soil back so that the crown of the plant is just 1 inch below the soil surface. That may change things for you.

Q: I bought some Potentilla bushes because the tags said they could survive in sun or part shade. They are all dying. I think it is because it is too shady where they were planted. Are there some flowering bushes that I could plant in a shady spot? It would maybe get a few hours of sunlight because there are large maple trees all around our house. (E-mail reference)

A: The Annabelle hydrangea flowers nicely in the shade.

Q: I have a question regarding my two new peace lilies. They have been flowering and look just great. However, I was wondering if I should clip the dead flowers after they turn brown. If so, should only the dead flower itself be clipped, or should the whole shoot be clipped? (E-mail reference)

A: Cut the entire stalk back when the flower fades.

Q: Every fall we have been getting webworms on our Canadian chokecherry trees. I noticed you suggest spraying with dormant oil and lime sulfur in early spring just before leaf-out to help prevent the web worms from coming back. But, I want to know what a person should do once the web worm is on the tree. We have been cutting the branches off and burning them. What else can we do? Is there some kind of spray that can be used to kill them in the web? Where can I find dormant oil and lime sulfur? (Turtle Lake, N.D.)

A: Once the webworms are noticed, they are very difficult to control, being virtually immune to sprays due to their protective webbing. You are doing the right thing by burning the branches that are infested. Lime sulfur and dormant or horticultural oil is available at most garden supply stores.

Q: My son bought a home in Wadena, Minn., last summer and has beautiful grapevines that produce delicious dark purple grapes. He does not know what kind they are. I would love to dig a few vines and transplant them in my back yard. Do grapes do well in southeastern North Dakota? If so, what time of the year should I try to move them and do they need much sun? Do the plants multiply? (Oakes, N.D.)

A: Grape vines can be propagated via serpentine layering. If you will send me your mailing address I will forward a copy of our publication "Home Propagation Techniques," which describes the process along with many others.

Q: I inherited two jade plants. They both seem to be very healthy, happy plants. I do not want to do anything to ruin their lives. One of them seems to be a bit large for its pot, meaning it leans a lot. Should it be repotted? Is it true that I don't have to water these plants very often? Once a month or twice a month? (E-mail reference)

A: Jade care is as follows: 1. Adequate bright light, with some direct sunlight. Too little will cause them to become spindly and flop over. 2. Keep them cool during winter, 55 degrees or lower to 45 degrees. Summer temperatures are OK as they occur. 3. Water to soak the root container during the active growth period of summer, and allow two thirds of the root ball to dry completely before rewatering. During winter rest period, water only enough to keep the root ball from completely drying. 4. Fertilizer should be applied, diluted, every two weeks during the period of active growth. 5. Repot every two years into the next larger sized container. 6. Propagation is by individual leaves or from 2-3 inch long stem cuttings. I hope this helps you keep your Jade plants healthy and you happy!

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: Gary Moran, (701) 231-7865, gmoran@ndsuext.nodak.edu