March 22, 2001

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: A number of years ago we planted a row of comfrey on one end of our garden. Over the years it has taken over our entire garden. I thought I could get rid of it by plowing it under, but the more I work the ground the worse it gets, for it regrows from the roots. Is there anything I can do to eradicate the comfrey without using chemicals? I want to keep our garden organic. (Dent, Minn.)

A: The organic way to control this and other persistent weeds, is to cover the area with black plastic, and cover that plastic with as much hay or old newspapers as you can spread. Leave it that way all growing season. This does two things: It eliminates light necessary for growth, and deprives the plant of good gas exchange so anaerobic (airless) conditions develop. Where "volunteers" or "escapes" show up, simply cook their goose literally, by pouring boiling water over the crown.

Q: We had a potato patch of some six varieties which yielded quite well, considering the drought we had. One variety, Russet Burbank, yielded well, except 90 percent of the tubers were all connected in the most grotesque and interesting shapes. Some were two or three nice-sized potatoes with many small ones attached. Is that normal for that variety? Second, one day our bush beans looked nice and healthy and I had a good picking. The next day I noticed many tiny black insects. We sprayed with Sevin, but then the plants turned yellow and died. I find others had the same problem. A neighbor planted later for a fall crop and had no difficulty.

A: I suspect the dry (and probably hot) weather had something to do with both problems.

Potatoes do best where 1 to 1 1/2 inch of water is applied each week, there is ample sunshine, and the temperatures are not high. Variations in moisture and temperature can cause strange things to happen. It is unusual for Sevin to cause the reaction you describe. I suspect some residue of herbicide may have been in the container you used. If not that, then something that was a petroleum base was in the container.

Q: I am having a problem with spruce trees in a shelter belt. Every year the needles on the bottom fall off a little farther up the trees. This started on one tree and now it has spread to two others. I am afraid that it will spread to more. Is there some kind of spray I could use to stop it from spreading? (New Salem, N.D.)

A: This could likely be one of two diseases; Cytospora canker or Rhizosphaera needle cast. The former malady causes individual branch total die-back, usually with lower branches first. The needles turn a purplish-brown before dropping off. If this fits the symptoms of your trees, remove the affected branches before spring arrives. There is no spray remedy. The latter disease works its way from the interior needles right out to where only the current season’s growth is not discolored. Where the disease has been around for years, entire branches could be killed. With this disease, spraying with Bravo (chlorothalonil) or Bordeau mixture when the needles are partially elongated, then again within 30 days, for at least two growing seasons will halt the progression of the disease.

Q: What is causing my evergreen trees to turn brown and what can be done to prevent it in the future? I assume the harsh winter we have had is the cause, but is it the wind burning them, sub-zero temps, reflection from the snow, or what in particular? Perhaps a combination of all of the above? My Mugo pine shrub was partially uncovered and the exposed areas got brown so I covered the whole thing with snow. The Ponderosa pine in our yard is showing some brown as are many other right in town. (Britton, S.D.)

A: The needles on your evergreens are drying out--desiccating--from a combination of factors: wind is pulling the moisture out of the needles, which are warmed by the bright sunlight, but it cannot be replaced because the moisture in the soil is frozen. Don’t worry. I’ve seen many evergreens recover by late May or early June that were assumed dead in February or March. The buds, which are now dormant, will many times emerge with fresh green needles in the spring.

Next fall, put a burlap barrier around the trees and spray with an anti-desiccant before freeze-up. Re-apply on a warm day in late winter (minimum temperature 40 degrees F) for extra insurance.

Q: One of your readers asked about the beautiful Hadspen blood astrantia. I had been searching local nurseries here in Oregon ever since I saw it featured in Better Homes and Gardens about two years ago. Last week I went to a nursery right by my home and found that they have several. It is Gossler Farms Nursery, 1200 Weaver Road, Springfield OR 97478, (541) 746-6611. They try to carry plants that are not usually stocked in other nurseries. (E-mail reference, Springfield, Ore.)

A: Thank you for that information! Readers who might be interested in that plant will be delighted to know where they can get it this spring.

Q: I recently bought a chenille plant and am wondering, are the chenille droppings poisonous? I have a daycare and the nursery didn't know. (E-mail reference)

A: None of my references indicate any cautions for poisonings. However, I would still exercise every caution around the children, as they could still choke on the chenilles or cattails, and the plant may have been sprayed with a long residual toxin at the greenhouse.

Q: We have a problem with striped flies, or some call them attic flies. I have also heard they thrive or come in with plants, but we don't have any plants in our house. Any suggestions on where they come from or how to get rid of them? We just tried "Tempo" and that seems to help but doesn't take care of the problem completely. (E-mail reference, Jamestown, N.D.)

A: I'm willing to bet that they are fruit flies that are starting to hatch with the warming weather. They are attracted to rotting wood, fruit waste, or compost, and of course are not active when it is so cold. Tempo is an effective insecticide for this problem, but as far as I know, it is listed for commercial use only. Be careful. Fill up sinks and tubs with hot water with about a 10 percent chlorine bleach solution and let it go down the drain. This will "sanitize" those sites and possibly eliminate the problem. Other than that, all I can recommend is patience. They will eventually move outside as the weather warms.

Q: I would like to plant a nice shade tree in my front yard but don’t want one that will get too tall. Someone suggested an Ohio buckeye or the Amur maple, but how tall do they get? (Edgeley, N.D.)

A: You could grow the two beautiful cultivars of Ohio buckeye, ‘Autumn Splendor’ and ‘Homestead’. Both are excellent mid-sized trees for residential properties, with excellent red-orange fall color. Amur and Tatarian maples can also be considered, with the same recommendation. Use the named cultivars for good performance, like ‘Embers’ and others. I have one of these in my back yard and totally enjoy it.

Q: I read your comments on amaryllis seeds. For the first time in five years, I also got some flat, black, wing-shaped things from a bulb like growth on a flower stalk. Are these useless, or can they be successfully planted? (E-mail reference)

A: Not useless. They are bulbills. Plant them, and in a few years they will be big and beautiful and able to then produce some flowers.

Q: I have a new problem with my beloved hibiscus. It is now wilting. Is it just shock from refreshing the soil last week? The soil is moist but not soggy. Could it be from leaving the Sevin dust on too long? I rinsed all the leaves today to get the dust off. (E-mail reference, Wichita, Kan.)

A: Most likely transplant shock. Cover the plant with a clear plastic bag, supported by bamboo stakes, after you have misted the foliage with distilled water. The wilted leaves may fall off, or they may rehydrate, depending on whether or not an abscission layer has formed. Either way, the plant will eventually recover. Just don't let it roast in direct sunlight with the bag over it!

Q: Last summer my young ash trees didn’t leaf out like they should. There were few leaves and some were curled on the edges. Last fall you mentioned this problem and suggested a spray before they leafed out in the spring. Could you please repeat that information before spring? Also, all of our longer needle pines have a lot of brown on the needles. Are they hurt? Does one need to spray them with something? (E-mail reference, Kimball, S.D.)

A: That was anthracnose that affects the ash trees in the spring. Spray the trees before leaf-out, just as the buds are beginning to swell, with lime-sulfur spray. This acts as a good sanitizer and should help to control the disease intensity somewhat. If the weather is in our favor, that too will help. Winter burn is common this year with many of the evergreens across the prairie states. Most will recover, although the needles that are all brown now will likely fall off. The buds that will open this spring should produce fresh foliage that will help to mask some of the winterburned foliage. Spray the trees next year just before freeze-up with an anti-desiccant, like Wilt-Pruf, to prevent moisture loss from the foliage during the winter. Respray the first above freezing day that occurs in February or early March.

Q: My mother is having a terrible problem with lady bugs in her house this winter. The upstairs bedroom on the southeast end is filled with them. Everyday she can sweep up around 80 of them. We have tried spraying them with Tempo. That kills them, but there is always a new batch coming in. What is causing this and is there any way to get rid of them? She thinks they might have come in with her outside plants as she winters over lots of plants in that room. (E-mail reference, Perham, Minn.)

A: Ouch! Spraying lady bugs. I hate to see it happen, but if they are pests, there is nothing you can do about it. I suppose it is better than having them starve. They are probably hatching or becoming activated with the warmer weather. If you will recall, last fall there was a very high population of them across our region. When the weather started to turn cold, many migrated into homes, looking for places to hibernate for the winter. Now they are waking up and there is no food for them. Not much you can do about their peskiness except what you have been doing, unless it is to use a vacuum to pick them up.

Q: I have a Thanksgiving cactus and it bloomed, but now it looks limp. Is it because I overwatered it? I also have a Christmas cactus that is blooming now, but some of the buds have fallen off. What is causing this? (Springfield, S.D.)

A: Cold or hot drafts can cause buds to drop. Overwatering can cause a root rot to develop which results in the limp appearance you are seeing in your plants. Back off on the watering, and your plants may recover if the problem hasn’t gone too far.

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