Q: Your previous article on weed control is spot-on regarding the limitations of weed control via vinegar, boiling water, sodium chloride, etc. I have tried all of them. None are very effective.
The article mentions preemergents with corn gluten. Does corn gluten do the job?
A: I did mention using corn gluten meal as a preemergent in the previous article. It has an interesting history. Back in the 1980s, Dr. Nick Christians at Iowa State University was doing an experiment to see if he could find a product to prevent the Pythium fungus from harming creeping bent grass that is commonly used on golf course greens. He used corn gluten meal (CGM) as the carrier for the fungus. As part of a good experiment, you make sure the carrier doesn't cause problems, so you apply just the carrier to some of the plots and nothing at all to some of the plots. He determined that the control plot with just the CGM had an unexpected result: the seedling grass plants did not grow.
Now he had a new experiment to test. In 1991 and 1993, he received patents for CGM products that worked to inhibit the growth of seeds. It turns out that proteins in the CGM stop the growth of the roots of seeds that are sprouting. It doesn't stop seeds from sprouting, just their root growth. It doesn't harm existing plants as they already have so many roots.
There are several advantages of CGM: It prevents many weeds from growing. It is very safe for people and pets. CGM contains 10% nitrogen by weight and makes an excellent fertilizer for plants with a well-established root system. It is a preemergence material only and has no postemergence effect on weeds that are already established.
The disadvantages include that the proper timing of the application can be difficult. It must be applied in the four to six weeks before the weeds are going to germinate. Seeds can delay or rush ahead with germination based on temperature changes in the weather. Seeds that have started to grow may develop enough of a root system to not be killed by the CGM. Along with the good plants, weed seeds that survive will be fed for about three months with the nitrogen in the CGM.
Another disadvantage is that some people are allergic to corn. Even if no one in your family is allergic, there can be exposure in the landscape that could affect neighbors.
Of course you must follow the label directions, but a rate of about 20 pounds per 1,000 square feet is typical. The CGM then needs to be watered in to move the chemicals into the soil. Too much water from rain can move the chemicals too deep in the soil to be effective. After that initial watering, it is best if the landscape stays dry. The CGM stays effective for about six weeks after application if it stays somewhat dry. It decomposes if it stays wet.
During the first year, the weeds may be reduced by 50%. It can take two to three years to achieve the same reduction in weeds as a single application of a synthetic preemergent herbicide. You will need to be patient, and you will spend more money when using CGM.
The liquid sprayable materials have been found to be less stable than the corn gluten meal in field studies. Current research is being directed at methods of stabilizing these soluble materials to improve their efficacy.
Don't be fooled. Every time someone comes up with a new product, other people will try to take shortcuts to try to get part of the sales. Corn gluten feed products and distillers grain products are sold at feed stores and garden stores. They are not the real products labeled for use as a preemergent, and they don't work. It is also not the cornmeal in the grocery store. Use that to make muffins.
DIST. BY CREATORS.COM
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