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Twenty Mule Team Borax kills creeping Charlie

Q: I planted strawberries three years ago. I'm not sure it was a good idea, but I allowed the spring crop to mature. Would fertilizing now to help the summer and fall crop be a good idea? Thank you!

A: Fertilizing after the fruit is borne is always a good idea. However, don't overdo the nitrogen. In other words, don't throw any leftover turf fertilizer on the strawberries. A 5-10-10 or 5-10-5 will do a nice job of reinvigorating the strawberry plants.

Q: We have two silver maples in our backyard that were healthy and growing for the six years we have lived in our home. They are huge, tall trees. This year, I noticed that a portion of one of the trees didn't leaf up as fast as the rest of the tree. The limb did fill in eventually. We called a tree specialist to look at the trees.

He told us the trees had spider mites that would kill the trees. In order to save the trees, he told us we would have to inject pesticide into the roots and allow the tree to draw it up and kill the mites. The process will cost $1,000, which would be hard for us to come up with. We love the trees, so I don't want to see them die. Is there any hope? Please help!

A: I'm all for the entrepreneur in our society making some money, but that sounds a little steep to me. I also question the diagnosis, unless we are talking about you living in a hot, dry climate.

Spider mites are active during the weather conditions I just described. Spider mites are rare, if not totally absent, during the cool, damp and rainy seasons of spring and fall. The fact that the branch did leaf out would lead me to believe that it is struggling with a canker or vascular disease of some kind. If that is the case, having the trees professionally fertilized would be an approach to consider, but it depends on the extent of damage.

This would stimulate growth and compartmentalize the disease areas. Such a treatment would cost far less than the injection of a miticide.

Q: I have a couple of young basswoods in my yard that I inadvertently damaged with a broadleaf herbicide (2-4 D Ester) trying to control creeping Charlie. Is there anything I can do for the trees? How long does the 2-4 D last in the soil? The basswoods seem really sensitive.

A nearby crab apple tree was unfazed. The tops of the basswoods seem to be the most affected by showing the most leaf curl. I don't believe drift is the problem. Does rain or lawn watering carry the herbicide to the roots? Is there a short-lived broadleaf herbicide that would kill the creeping Charlie and then break down quickly?

My creeping Charlie problem is bad. A nearby patch of woods has a solid blanket of the stuff. Any thoughts on how to keep it out of the lawn without killing my trees? I really enjoy reading your Hortiscope pages!

A: A linden tree the age you describe should have no trouble recovering from the herbicide drift that probably occurred during a rain event. With the heavy infestation of creeping Charlie that you describe, you are a perfect candidate to use Twenty Mule Team Borax.

Dissolve 10 ounces of Borax in 4 ounces of warm water. Add the mixture to 2 1/2 gallons of water. This is enough to treat 1,000 square feet. My colleague, Harlene Hatterman-Valenti, was a pioneer in the use of this material when she was working on her degree at Iowa Stage University.

Be aware that boron is an element used by plants for growth, but in microdoses. What the plant is getting is a macrodose that will be toxic to it. If you live in a part of the country that is high in boron, applying this strong dose may make it inhospitable for your lawn grass. The alternative is to accept this weed as your lawn to save on the frustration of attempting to get rid of it.

To contact Ron Smith for answers to your questions, write to Ron Smith, NDSU Department of Plant Sciences, Dept. 7670, Box 6050, Fargo, ND 58108-6050 or e-mail