NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665

July 1, 1999

Ron Smith, Extension Horticulturist
North Dakota State University

Q: Is there anything I can spray on my asparagus patch to kill weeds but not the asparagus? (Doland, S.D.)

A: For the first year a hand weeding is the only way, but in subsequent years, the use of herbicides is recommended. Some herbicides to use are Treflan, Poast, Sencor 4 and Trific 60D7. Make sure to follow all label directions.

Q: Can you tell me what the orange circles on the leaves and branches of my green ash are and how to get rid of them? (Marion, N.D.)

A: Ash trees are having a tough time this year and yours doesn't appear to be an exception. Ash anthracnose is the disease that is hitting your tree, along with many other ashes across the region.

About the only thing you can do at this stage is fertilize with something like 10-10-10, and clean up the fallen leaf litter completely this fall. The tree should re-leaf in a couple of weeks, and unless the tree is in poor health or subject to other stress, it should recover. It is seldom fatal to the tree unless the pathogen occurs several years in a row.

Next spring if it looks like a cool-wet spell, spray at bud swelling with lime sulfur. Two other sprays should be applied, one at leaf expansion, and the second about 10 days later, using Daconil 2787 fungicide, at a rate of 2 teaspoons per gallon of water.

Q: There are "balls" growing on my oak tree. What are they? (Galesburg, N.D.)

A: Your sample was of the oak bullet gall wasp—Disholocaspis quercusmammor. Their damage is cosmetic, not lethal. No control is necessary or practical.

Q: Can you save seed for the next year from kohlrabi, turnips, radishes, carrots, rutabagas and bushbeans? Will inbreeding be a problem? I also would like some information on how to keep squirrels out of my garden. (Berkley, Mich.)

A: I've only saved seeds from beans and carrots before, and it didn't seem to be worth the effort on the biennial plants. But, if you would still like to, here is the information I was able to find.

For bush beans, which are annuals, you must allow the pods to reach full maturity and dry up. You can harvest the seeds in early fall/late summer from the dried pods.

Carrots, which are biennials, take two growing seasons to get seeds. Store the carrots after the first season in a cool, dry place without their tops. Replant the root in the spring and it will send up a flowery stalk. This will set seed in late summer. Collect seed after it dries up.

Radishes, which are annuals, flower the same season, sending up a long flowering stalk—but I've never seen the seeds.

For turnips, kohlrabi and rutabagas, which are biennials, you must dig up roots after the first year and replant the second year. They will then send up a flowering stalk the second year.

Use Ro-pel to keep squirrels out. Ro-pel is used to keep rodents away. Spray on your plants once a year, but make sure not to spray it on any edibles! Other things to try include hot pepper spray and cheap men's colognes.

Good luck and thanks for writing!

Q: I have a Crown of Thorns plant that bloomed for a long time, but now it hasn't bloomed for quite a while. It is kind of an ugly plant with many thorns on it, and I am wondering what to do to get it to bloom again. (Mahnomen, Minn.)

A: A very prickly plant indeed! It might help to prune some branches back to their connecting branches to get it to bloom again; otherwise, if you are not too attached to it, I would get rid of it. I consider it a hazard to people!

Q: I have a question about my green ash tree. The leaves are curling and when I open them up there are a lot frost white little bugs. Should I spray the tree with something or leave it alone? (e-mail)

A: I would recommend a spray of either Malathion, Sevin or Orthene (which is systemic and contact). They could be mealybugs or aphids (most likely the latter), but either way, we don't want them to get out of hand.

Q: We have a very large, old maple tree that takes up most of our back yard. This year the leaves have masses of small bumps on them. Some are bright green and some red. Is this something we need to be concerned about? (e-mail)

A: Not a bit to be concerned about! The tree is likely a silver maple and the bumps are the result of mite feeding earlier in the season. So enjoy this harmless, interesting wonder of nature.

Q: Is there any grass that will grow under a cottonwood tree? We are having trouble with getting anything to grow. I remember once seeing a chart that had the pH that trees contributed to the soil, but I can't remember where I saw it. Might you know? Thanks for the help. (Detroit Lakes, Minn., e-mail)

A: There will be very little luck growing decent grass under a cottonwood. You might be better off planting it to a wildflower selection that would tolerate shade and cover the exposed roots. It will also be a lot easier on the mower as well--not bouncing over those surface roots.

I have seen the chart you made reference to but cannot put my hands on one now. If I should uncover it, I'll pass it on.

Q: Can you tell me how to control quackgrass in my iris bed? I also would like to know if there is anything I can spray on my crabapple tree to prevent suckering? (e-mail)

A: Quack in iris beds is a tough one to get under control. Poast can be used, but I am finding out it is difficult to find. The only other option is dig the bed up and remove the quack by hand.

No, there is nothing you can spray on the roots of the crabapple to prevent suckering. You might try cutting the suckers off with a weed cutter that goes below the soil surface and raising the mower height to 3 inches if it isn't already there. Sometimes that procedure will at least reduce the number of suckers that have to be dealt with!

Q: I have read that to create a thick (multiple branched) hedge you should cut back the top third of new hedge plantings by one-third for the first three years. I have a one-year-old villosa lilac hedge. Does the one-third off for three years work for villosa lilacs? (e-mail)

A: You bet it does! Try to get it done before July 4 so it will have time to set new flower buds for next year.

Q: Due to the wet cycle we are in, I now have a small pond behind my home. I would like to keep part of the pond open and free of cattails for skating in the winter. The cattails are taking over more every year and restricting our view of the pond from the house, which I really enjoyed. How can I get rid of the cattails and safely keep them under control? (Huron, S.D., e-mail)

A: Cattails a problem? That is a question I thought I would never see from anyone, and I do not know of an acceptable way of getting rid of them. Perhaps one of our readers will know when they see this in the paper and send me a response. If that happens I'll gladly pass the answer on to you!

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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: Dean Hulse (701) 231-6136