November 21, 2001

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I have a chenille plant that is growing great. I have it in a room with lots of light but not direct sun on the plant (at least most of the time). The plant is now showing yellow at the tips of the entire leaf "points." Is this a lack of fertilizer, or the sun shining on it some of the time, or is it a pest of some sort? (E-mail reference)

A: It sounds like salt burn. This could be caused by keeping the plant in a pot that is not freely draining and the fertilizer or water salts are building up to the point where this tip burn is now taking place. I'd suggest repotting in a free-flowing pot, with fresh potting soil, and fertilizing lightly every two weeks only during active periods of grown. It could also be that the direct sunlight is too much, so try moving it back a little from the source. Also, it could be low humidity or just simple senescence of the older leaves.

Q: I am trying to propagate a jade plant. I let the branch air for a week or so, till it crumpled over the stem where I cut it. I planted it in dirt, where it’s been for about two weeks. I noticed it was leaning to one side, and while trying to right it I pulled it out of the dirt and noticed how mushy the stem was in the dirt. What should I do? I don't want to lose my nice branch cutting. (E-mail reference)

A: I would suggest making a fresh cut--diagonally and this time place it in a 50/50 sand/peat mixture. Keep the mixture moist but not wet, allowing the top inch to dry between waterings. Keep the plant in diffused light, in a warm room, giving it liquid fertilizer (such as Schultz's) once a month. In about three months it should be rooted. If this one bites the dust, try again in the spring.

Q: I am house sitting for some friends that own several cyclamens. In a note, I was asked to put the cyclamens in a foot of water twice a week. Is that true, and if so, do I simply submerge the whole plant in water like in the sink? Does the water have to cover the whole plant, leaves and all? And for how long do they stay submerged? (E-mail reference)

A: Cyclamen should be watered from below by placing the pots in a shallow water-filled bowl or pan; this permits the potting mixture to take up as much water as it needs. After 10 minutes the pots should be lifted out and permitted to drain. Never allow water to be poured on the leaves.

Your friends only gave you partial information and advice--dangerous, because if you had immersed the plants completely they very well could expire. And, they are very expensive to replace.

Q: My mother in law has some type of flowering crab that has lost most of its leaves. The remaining leaves look like they are drying up. The fruit looks perfect, but seems a little small. I've looked up apple scab and it doesn't look like the pictures. It's planted in very sandy soil. We don't like using chemicals. Any suggestions? (E-mail reference)

A: With no chemicals being used, you are then limiting yourself to very few choices: Put up with what is happening and hope that the weather improves over the years so that the disease doesn't manifest itself to such an extent. You can help lessen the impact of the disease by cleaning up all fallen leaves in the autumn. Spraying with lime-sulfur (approved for organic use) will help to sanitize the tree when dormant but is not listed as a control for the disease. Or, remove the present tree and replace with a more resistant cultivar, which depends on where you live.

Q: When is the best time to cut back my juniper bushes? Can I do it now or would I be better off to wait? Is there a product on the market I can use to spot treat the quackgrass in my lawn without killing the other grass, which is mostly Kentucky bluegrass? (Jamestown, N.D.)

A: You are better to wait until next spring before new growth begins on the junipers.

On the quackgrass control, no, sorry, there’s nothing on the market.

Q: On numerous occasions you have recommended using Trimec for weed control in yards. My question is, where can Trimec be purchased? Several years ago I believe I picked it up at Menards, but now they say they don't carry it. (Lake City, S.D.)

A: If they are not carrying Trimec, what are they recommending for lawn weed control? It might have a very similar formula, just a different name. Trimec is a trademark name of the PBI Gordon Company. I would try local garden centers and stores like Target, Wal-Mart, and K-Mart. Someone should be carrying it in your area.

Q: The cottonwood tree in my backyard has a branch that is forming (for lack of a better term) in two spots. What is causing this condition? Another question I have is what would cause six or so rust colored spots on the base of a cottonwood tree? (E-mail reference)

A: I think you mean that the branch is forming a "Y" crotch, which could be dangerous as the tree lays down more wood in that area with the developing branches. I suggest selecting one or the other and make that the leader. Generally the lesser of the two is selected to be removed. The rust-colored spots could be the result of slime flux, an exuding of the sap that has fermented in the interior of the tree, causing a build-up of pressure that causes the material to ooze out. Have the tree checked out by a forester or arborist to make sure the core hasn't rotted. These are my best guesses based on your have description.

Q: It is time for repairing a lawn in a relatively dry area with lots of shade trees. What do you recommend for this type of planting? The soil is by a lake on a high bank area and appears to be of a type that was blown from lake bottom as it is very fine and seems to pack. The grass in the treeless areas grows like crazy. (E-mail reference, Perham, Minn.)

A: The best grass for shade areas is creeping red fescue. It will thrive under those conditions and make an attractive lawn. Try to get 'Ruby' or 'Dawson' cultivars. In our trials at NDSU, they have performed the best.

Q: I have two different Christmas cactus, one has a narrower leaf than the other. I have them in a north window, but neither one blooms for me. I had them repotted this summer at a greenhouse. Would you please tell me how to care for them and what am I doing wrong? (Breckenridge, Minn.)

A: The Christmas cactus is a jungle sub-canopy species that is never exposed to full sunlight. The flower buds form at this time of year with the restricted light of shortening autumn days. However, we mess up the cycle by turning on the lights when it get dark! So, cover the plants with a black or otherwise light-proof cloth, giving them short days of less than 12 hours. I suggest playing it safe and giving them just 10 hours of light and 14 hours of darkness. Cover at 5 p.m. and uncover at 7 a.m. Continue until flower buds are evident.

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