Questions on: Oxalis

Ron Smith, Horticulturist, NDSU Extension Service


Q. Two different weeds seem to be taking over my lawn. The one with yellow flowers seems to be spreading fast and killing the grass. If you could tell me what it is and how to kill or control it, I would be grateful. (Minot, N.D.)

A. The yellow flowered weed is likely either black medic or oxalis. Not a problem either way, as several herbicides on the market will provide control. Weedone DPC amine or Trimec will do the job nicely for you.

The other one is probably field bindweed. It will take repeat applications of Trimec or Weedone to get rid of this one if it is well established.


Q: I have a plant growing in my yard. It really isn't an offensive plant and makes a nice ground cover, especially in my rock garden. My daughter says that in South Dakota they call it "eating grass" and it has a slight lemon flavor. What is it? (New Salem, N.D.)

A: Your "eating grass" is actually oxalis--or yellow woodsorrel--a pesky weed in gardens and especially greenhouses. It pulls up easily, and makes a tasty addition to salads. You'll never go without it unless you start using herbicides. Even then, this weed may win!


Q. I read in your article about a person that was looking for a source for oxalis bulbs and I have a source for you: Henry Field's Seeds and Nursery Co., 415 North Burnett, Shenandoah, Iowa, 51602. The company advertises these bulbs in its 1998 Spring Catalog, Page 86, right hand column, second item down. A dozen bulbs cost 95 cents.

A. Many, many thanks for the information! I really enjoy this aspect of the column. What I don't know someone else is bound to know and is willing to share it with the readers!


Q: Can you tell me where I can purchase some oxalis bulbs? (Martin, S.D.)

A: Come to our campus! We have plenty of oxalis growing everywhere, but not the kind you want, I'm sure! Quite frankly, I don't know where you can get these interesting plants from. I only know they show up at retail outlets around St. Patrick's Day. You might check with some local florists and see if they can get any for you.


Q. Thanks for all of your help in the past. I really do appreciate it.

Would you please tell me what kind of weeds these are?

Also would you please tell me what is wrong with this mock orange? I read to spray with fixed coppers for blight. What are fixed coppers?

How do I tell if I have a male or female bitter sweet vine? I read also that you have to have both.

I bought some Tempo for grasshoppers but it does not list grasshoppers on it to kill. I was told not to use it in the garden. It does not say this either.

How do shamrock plants go dormant? Do they lose their leaves or just not flower? (Winner, S.D.)

A. The weeds are barnyard grass and oxalis or wood sorrel. The third one is prostrate kurtweed

The mock orange has septoria leaf spot. Protect next spring after leaf-out with a multipurpose fungicide such as Bordeaux mixture, which contains the copper you are asking about.

Bitter sweet are like holly bushes--no two sexes, no fruit--but will grow anyway. I guess you have to depend on the integrity of the nursery to include both sexes in the container.

Tempo can be used in the landscape and on lawns for good grasshopper control. Use either Malathion or Sevin in your garden.

Shamrock is a name given to many species of clover-like plants, generally Oxalis species. The ones I know set seed and die, with the seed sprouting later.


Q.There are two weeds I would like to know how to kill. The small one has little yellow flowers. It is taking over my lawn. We had professionals spray our lawn and still they keep coming back. What are the names of the two weeds?

The large leaves with brown spots are from our flowering bush. Is this serious? Also, when they planted it they never told me how to take care of it. Do I cut it down in the fall after it turns brown or do I cut it only in the spring? Will it get as large as it is now, which is about 10 feet?

Read your articles all the time and they are a great help to me. Thank you.

Also, did I send the samples correctly? Thank you again. (Valley City, N.D.)

A.Your two weed samples were oxalis (small one taking over your lawn) and wormseed mustard. Both are annuals producing lots of seed.

The best approach is to have your lawn service apply a pre-emergent next spring. That will keep them from germinating.

Your shrub is a Rhus, or smooth sumac. It is showing a leaf spot

fungus which at this time you can do nothing about. Clean up fallen leaves this autumn and apply a multipurpose fungicide next spring, after the leaves emerge, as a protectant.

Your samples were not properly sent, although my good secretary rescued them! Samples should be sent dry and in ziplock bags.

Thank you.


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