New Article for July 6, 2009 from LSU AgCenter County Agent Kenny Sharpe of Livingston Parish:
The spring vegetable gardens are starting to play out, and the heat of summer is raging. Now would be a good time to clean up some of your garden weed problems.
In Louisiana there is no such thing as fallow ground without weeds. The only way to keep weeds out is constant control. The oldest method of weed control, which is still very effective, is cultivation. You can plow, disk or till the soil to destroy the weeds and then every few weeks come back and repeat the process to destroy the newly emerged plants before they have a chance to go to seed.
This approach has the drawback of making your garden prone to erosion, if we ever get the summer rains.
Another approach to garden weed control is by using a nonselective herbicide such a glyphosate, which is sold as Roundup and various other retail names.
If the weeds have gotten tall, either mow them down and use a string trimmer to get them close to the ground. Give the grass a few days to start growing again and then treat. One word of caution is that the glyphosate products only work on actively growing green vegetation. In drought conditions the grass and weeds are not actively growing and usually will not be killed. Wait until a few days after a rain to apply if it has been weeks since you have had rain.
Another note is that the glyphosate products will not do any good if you spray them on bare ground to stop weeds from emerging. The glyphosate will immediately bind to the soil particles, making it very safe to use but ineffective as a pre-emergence herbicide.
I shudder at the thought of giving rates of application because there are so many concentrations of the glyphosate products. The full strength products will be about 40 percent glyphosate and can be used at 1.28 to 2.56 ounces per gallon of water. On all the products you should follow the label recommendations for application and rates.
I would spray the herbicide and then repeat in four to six weeks when new plants emerge. It takes from 10 to 14 days before the herbicide translocates all the way through the plant to the roots to give you a good kill. This is the only way I know to get rid of cocco grass (purple nutsedge) and it will take a few years of being persistent.
After either cultivation or herbicide treatments, it is a great plan to plant a cover crop to shade out weeds. I like southern peas. You can plant them in the heat of summer. They will shade out the weeds, hold the soil in place during rains and can be picked in about 60 days. In addition, you can plow the pea vines into the soil to add organic matter, and since peas are a legume, you also add nitrogen to the soil.
Recommended Southern peas types and varieties would include: Purple-Hull pea types – Pinkeye Purple Hull, Texas Pinkeye, Quick Pick and Mississippi Pinkeye Purple Hull; Crowder pea types –Mississippi Purple, Mississippi Silver, Mississippi Shipper and Dixie Lee; Blackeye pea types- Magnolia Blackeye, Royal Blackeye and Queen Ann; Cream pea types- Elite.
At a spacing of 4-6 inches it should take about 4-6 ounces of pea seed per 100 feet of row.
For more information on these or related topics, contact Kenny at 225-686-3020.