With the rainfall last fall and during early winter, many area pastures have a few weeds that will soon be competing with pasture grasses for whatever moisture is still available. It has been estimated that every pound of weeds controlled can return three to seven pounds of forage. That makes this spring’s transition into summer a critical period to address weed control issues and improve our forage production potential.
Also, taking care of weed problems now prior to cotton planting and emergence minimizes risk of causing damage to crops that may be sensitive to many broadleaf herbicides.
An integrated weed management strategy can include cultural, mechanical, chemical and biological controls. Cultural and biological practices might include strategic fertilizer application and timing, irrigation, aeration, and grazing manipulation.
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Often growers practice these without realizing they also impact their weed control program. Most often forage producers focus on mechanical or chemical weed control options and often pondering which method is more advantageous.
Mowing pastures for weed control is rarely recommended, and there are several reasons why. Mowing may make the place look better for a while, but that's about it.
First, it costs as much or more to mow as it does to spray. In fact, a cost comparison done in 2003 actually showed a $2.74 per acre savings from spraying versus shredding. The study estimated the cost associated with mowing one acre with a 40-horsepower tractor pulling a 6-foot rotary mower. The cost of shredding came to $14.24 per acre. This was compared to the same tractor pulling a 30- foot boom sprayer applying 1 quart of Grazon P&D per acre. The cost of spraying came to $11.50 per acre. The cost savings came from reductions in equipment cost and maintenance as well as reduced labor. Since then, the cost of machinery, labor and fuel has increased significantly, but the prices of many pasture herbicides have been relatively static if not lower due to generic alternatives.
Second, mowing cuts down forage as it cuts down weeds. Years ago Dr. David Bade, an agronomist with the Texas Agricultural Experiment Station, looked at forage response to chemical verses mechanical weed control. In a wet year under fertilized conditions, shredding increased forage production by 2,500 pounds and reduced weeds by 5,200 pounds per acre. However, early herbicide application increased forage production by 5,700 pounds and reduced weeds by 7,400 pounds per acre. In a dry year, shredding actually decreased forage production by 70 pounds per acre, while early herbicide application increased forage production by 1,500 pounds per acre.
And finally, almost all major weeds and brush will re-grow after mowing. With weeds this means that a weedy field stays weedy, but when dealing with brush species this can cause serious problems for any future control measures a producer may implement.
Texas A&M AgriLife Extension publications “Chemical Weed and Brush Control Suggestions for Rangeland B-1466” and “Suggestions for Weed Control in Pastures and Forages B-5038” are good resources for making weed and brush control decisions. Also, forage producers will have an opportunity to attend the Grass Grower’s Gathering to be held at the Johnny Calderon Building in Robstown, Texas on March 27. In addition to weed control, produces will also have an opportunity to learn about fertility management, forage selection options, assessing forage value, and dealing with forage production risk. For more information on the Grass Grower’s Gathering or weed and brush management contact us at 361.767.5223 or on the web at http://nueces.agrilife.org/.