June 20, 2002

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: Can you give me any insight on why Christmas cactus leaves may turn pink? ( Mandan, N.D.)

A: No, I can’t, unless you have it in front of or near an air conditioner vent that blows cool air and the plant is losing chlorophyll and the anthocyanin (red-pink pigment) is being expressed.

Q: A local gardener asked me about her pepper plants that are turning yellow and the leaves are falling off. This happened suddenly (one or two days). Nothing else in the garden seems to be affected. She has several different types of peppers and they all are affected. I was trying to research possible diseases. I found information on Fusarium and Verticillium wilt. The symptoms seem similar. Could this be a possibility? If not, any ideas? Treatments? (Napoleon, N.D.)

A: Peppers are extremely sensitive to temperature changes and moisture fluctuations. If the plants were not "conditioned" (I cannot use the word hardened, as they never truly harden off!) and purchased from a greenhouse operation where the elements could be controlled somewhat, they would be even more vulnerable to this problem. There is a chance they may re-leaf, or she may just want to go ahead and replant. The best thing peppers could use now is some continuous heat -- not the yo-yo temperatures from the 80s to the 50s!

Q: Last summer we cut down my red Canadian cherry tree and now there are shoots coming out. Some of these shoots are 3 to 4 feet tall. I thought I would just leave them and see what it does but I just checked and it is full of worms. They are thick on there and have eaten all the leaves off some of the shoots. I did spray with Raid as it was the quickest and easiest thing to spray with at the time. What do I do now? Will these worms invade any other trees or shrubs? What do you suggest? (Tappan, N.D.)

A: The "worms" you are referring to are likely canker worms ( Paleocrita vernata) or a similar species that are tree defoliators, with apples and cherries being among their favorite to feed upon. The population peaks, then levels off to almost being unnoticeable for a few years before building back up again. Healthy plant material can tolerate a defoliation or two, but nothing more. Spraying (malathion, Sevin, etc.) will give partial control, but the ones that are missed or survive the spraying may live on to reproduce more resistant characters in future years.

Generally they are pretty host specific and will not move too far from where they are. They will go through a metamorphosis and emerge as either adult males or females to continue the cycle again next spring. Be careful spraying with pressurized insecticides. The carrier could cause physical damage to the plants. Actually, there is a product on the market that would be better (for both you and the plant, but not the insect!) sold under the Schultz product line, called Fungicide 3, which uses Neem oil, a natural product from the Neem tree, which kills all kinds of chewing insects, controls many fungal diseases, and acts as a miticide as well. It should be available in most stores that sell garden products. Rather than being pressurized with a carrier, it is in a pump container that is easily used.

Q: Over 10 years ago we planted two parallel rows of Ponderosa pines as a windbreak/screen around our suburban 3-acre lot. We also have ash, spruce and other trees in the windbreak as well. The Ponderosas have done very well but typical of that tree they are losing their lower branches as they grow. Is there anything we can plant between the rows that would serve as a screen when the lower branches are gone from the Ponderosas? As you can imagine it is quite shaded and filled with pine needles. There is not a weed problem as they are shaded/ mulched out by the pines. (Bismarck, N.D.)

A: Would you consider deciduous shrubs like honeysuckle or lilacs? Annabelle hydrangea, currants, dogwood, and viburnum would all do well in shade. About the only evergreen you could use is the mugo pine. You will have to scrape the needles out of the area you want to plant to get anything established. When I lived in Georgia, I enjoyed walking through pine woods because of the mulch formed from the needles and the lack of any significant undergrowth.

Q: I was looking at a caragana hedge and found some evidence of fireblight from last year. Also, I found a few places in the hedge where a few leaves where matted together, about 2 inches long and 1 inch or less wide. I see about a dozen in a location, then I may go 20 feet before I see another group. Any ideas? (Fessenden, N.D.)

A: The old fire blight injury should be pruned out ASAP. The matted foliage is probably the resting place of pear slugs, which are actually the larval stage of a sawfly that skeletonizes foliage. Spray with Sevin to control.

Q: I'm trying to propagate cuttings from a bleeding heart and a vining honeysuckle. I plan to taking cuttings about 6 to 10 inches long, dip them in rooting hormone and put them in a starter mixture of soil, and cover the top with a plastic bag. Is this correct for both types of cuttings? If not what else? And what about temperature and sunlight? And approximately how long before I will know they took or I can plant them in a new location? (Mayville, N.D.)

A: You are right on in both cases. Just make sure the bleeding heart is done flowering, and you can use either stem or root cuttings. The vining honeysuckle can be propagated via serpentine layering while attached to the plant. Do you have a copy of my "Home Propagation Techniques" circular? If not, give me your address and I'll send a copy to you. As far as temperature and light goes: bright, indirect light -- not direct sunlight -- and room temperatures (70-ish) would do fine. You should see some roots in about six weeks. When the roots look large enough -- about the size of a woman's fist -- they should be able to support the new plant out of their protected environment provided some extended TLC was carried out.

Q: I transplanted a hybrid tea rose (Perfume Delight) in the spring of 2000 before it came out of dormancy. The following season it had good growth and foliage but no flowers. I continued to fertilize and give general care as usual. In 2001 it continued good growth and foliage but only had one bud. When it opened it was a small, magenta colored flower. In 2002, again it looks good and now has many buds but the flowers are small, magenta colored, and no fragrance. It is almost as if the hybrid tea has turned into a shrub rose. Before I moved it it had big, pink, and very scented flowers. What happened? (Onida, S.D.)

A: The only thing I can guess is that the scion or budwood, killed off when you moved it, and what you are seeing now is the growth coming from the rootstock, which, of course, is a rose, but not the hybrid tea that you wanted.

Q: We just planted a couple variegated dogwood bushes a few weeks ago in the front of our house (mostly shaded). The leaves are wilting on one of the bushes and the other is starting to. We've gotten plenty of rain -- the soil is damp. Any ideas? (Minneapolis, Minn.)

A: Transplant shock, perhaps. I assume they were guaranteed by the nursery. I would give them a few weeks to see if they pull out of the slump, and if they don't, take them back.

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