Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: We will start excavation for a new home in the spring on the prairie in southwest North Dakota. There is prairie cactus everywhere you step. I am wondering if after the site is leveled and grass is seeded we will still have problems with cactus among the grass. Are there any chemicals we can use to get rid of the cactus before we even begin the dirt work? (E-mail reference, N.D.)

A: Cactus is seldom a problem with a renovated lawn that receives proper care. If you get a chance, visit our trial sites at the Dickinson Research Extension Center (DREC) to see what grass cover appeals to you with the inputs you want to make.

Q: It appears the yellow jackets have moved from the compost heap (We hired specialists to remove them) to a small nest under the eaves, whence last fall several sneaked into the house and one hid out in a shoe and gave me a good sting. Just today we noticed the nest. What's the etiquette of dealing with nesting yellow jackets? Can we just knock it down? Say, put a garbage can underneath, and take a swat with a broom? As I understand it, there are queens left in the nest, overwintering. No doubt they'd be unhappy, but can they do anything about it? (E-mail reference, Bismarck, N.D.)

A: If you are talking about this time of year and outside, you have nothing to worry about now. If you are talking about inside or doing it during the growing season, you're a lot braver than I! Swatting at a wasp's nest is not my idea of sport that is fun.

Q: I have had my goldfish plant for a year now. We live in New York, so it stays indoors in direct sunlight and it blooms most of the time. I water it once a week with two 8-ounce bottles full of water. My question is, can you regrow plants from the pruning scraps (like you can with a spider plant)? (E-mail reference, N.Y.)

A: Thanks for giving me your location. Yes, a goldfish plant can be propagated from stem cuttings after it is finished flowering. They will root best if provided with bottom heat and a rooting hormone is used.

Q: I just replanted my two philodendron plants into larger pots and now they both appear to not be doing so well. A few of their leaves have turned bright yellow and appear to be dying. I water them with distilled water only and they get a moderate amount of sunlight. They were flourishing before I repotted them. What did I do wrong and what can I do to prevent them from dying? (E-mail reference)

A: Generally, the philodendron group is a pretty durable one to select from for houseplants, so I doubt your problem is a serious one. Check your watering habits. The Monstera philodendron likes to have the soil just moist during the winter months. Keeping it too wet (which is common right after repotting) causes waterlogging and could lead to the leaves turning yellow. Another cause for foliar yellowing is underfeeding. While not heavy feeders, they do need a fertilization at least every 60 days in the normal potting soil. When you say they get a moderate amount of sunlight, I assume you have them placed in the same location that you previously had them in. They should never receive direct sunlight, only bright, diffused light.

Q: How often should you water and feed spider plants? (E-mail reference, Kalamazoo, M.I.)

A: The spider plant (Chlorophytum) barely needs water during the winter months, so water sparingly. I have one at home, and my wife waters it thoroughly about once every two weeks and it is growing beautifully. She takes it down, places it in the bathtub and gives it a "tepid shower" and the plant thrives. Summertime watering should be a little more liberal.

Q: What chemicals could you recommend to kill off silver poplar? I am in New Zealand so this tree gets a real long season and the suckers it sends up are taking over. Are the suckers independent of the main trunk? Do I need to cut and poison each one? (E-mail reference, New Zealand)

A: The silver poplar -- Populus alba -- is a tough tree that withstands most stresses in the environment, including but not limited to having the roots covered with blacktop or concrete for a parking lot, compaction from continuous vehicle traffic, salt spray from snow covered streets, and more. Killing it will not be easy. You want to get a systemic herbicide that will translocate through the vascular system. As extensive as the roots are on this species, you will have to likely fight it for a couple of years. Spray the foliage that comes up with a product that contains glyphosate (Roundup in the U.S.). Allow the sucker to sprout to a couple of feet in height if you can, then spray it completely. The material will kill any green vegetation it touches. Material that simply burns the foliage back is not effective in getting complete control and will only frustrate you. Whatever you have available in New Zealand that translocates once applied is what you want to use. Just hang in there and persist - you will eventually win, I promise!

Q: Enclosed is a picture of our summit ash tree. There is something on the tree and is also on many of the ash tree in the neighborhood. We treated the tree with an insecticide through a root feeder and also sprayed with Ortho’s Isotox Insect Killer Formula IV in the spring and again in August, but it hasn’t seemed to help. Do you know what is affecting our trees and what we can do? (Wahpeton, N.D.)

A: The ash trees are suffering from an invasion of the flower gall mite. They attack the male flowers on the trees (some ash trees only bear female flowers) causing them to fuse together in a distorted manner. To some folks, this distortion is unsightly, to others, not. For sprays to be effective, they must be used when the blossoms start to form in spring. In my view, as long as the health of the tree is not compromised, it isn’t worth the time, expense, and environmental assault to spray for such a harmless pest.

Q: In reading your column I noted that someone was looking for a source for banana apple trees. I received this week a catalog from Miller Nurseries, 5060 West Lake Road, Canadaigua, N.Y. 14424-8904, phone (800) 836-9630. In the catalog it lists the Winter Banana apple, a semi-dwarf. It is described as having an aroma similar to bananas. They call it an heirloom variety and may be the one you were looking for. I worked for Gurney’s Seed & Nursery Co. at Yankton, S.D. for the past 15 spring seasons, and really enjoy reading your column. I agree with most of what you say in the column and sometimes learn something new! (Springfield, S.D.)

A: Thank you for the info. I believe you are the third person to inform me of this apple, and I appreciate your interest!

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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.

Source: Ron Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
Editor: Gary Moran, (701) 231-7865, gmoran@ndsuext.nodak.edu