The cost of hand-treating huisache recently got cheaper. Control with a new low-cost leaf spray is on par with other individual plant treatments on the thorny pest, and it’s easy to do.
The cost-effective new treatment is a hand-applied leaf spray using a 1% concentration of Grazon* P+D herbicide in water, applied in the fall. The Texas Agricultural Extension Service added the treatment to its recommendations last year.
The huisache recommendation with Grazon P+D is for individual plant treatment only, not broadcast application.
While Grazon P+D is promoted primarily for season-long control of broadleaf weeds in pastures - and priced accordingly - it’s also effective on several species of brush. But only recently did researchers discover that huisache was one of them.
In 1996 and 1997, the Extension service established a series of 13 result demonstrations testing Grazon P+D on huisache in 12 South Texas counties. All plots but one were sprayed in October or November.
Evaluated a year after treatment, huisache root kills in the leaf-spray plots ranged from 56% to 100%. The plots averaged 84% root kill, according to Dr. Wayne Hanselka, Exten-sion range specialist, Cor-pus Christi. In most cases - 10 out of the 13 plots - huisache root kills were 80% or better.
One of the demonstrations was in Karnes Coun-ty, on Zachary Yanta’s ranch near Runge, Texas. There county Extension agent Dennis Hale compared three methods of hand-treating huisache. Compared on a cost-per-killed-plant basis, the leaf spray with Grazon P+D was the most cost-effective.
In one of Yanta’s im-proved coastal bermudagrass pastures, Hale treated multi-stemmed re-growth huisache on November 21, 1997. Growing in an average density of 125 plants per acre, the huisache plants were about four to six feet tall, with two to four stems per plant and healthy foliage.
For the leaf spray, Hale used a mix of 1% Grazon P+D, 1/2% surfactant and water to fill his backpack sprayer. He sprayed all the leaves until they were wet, but not dripping - “about like leaves look on a dewy morning,” he says. Thoroughly covering the foliage is important with any foliar application. The leaf spray posted 83% control with a herbicide cost of
$7.35 per acre. Cost per killed plant: 7 cents. Hale didn’t figure a labor costs, but he did calculate the time it took to treat an acre. The leaf spray was the fastest treatment: 45 minutes to treat one acre with 125 plants.
For a conventional basal application, Hale used a mix of 2% Remedy* herbicide and 98% diesel (no water). With a backpack sprayer, he sprayed each stem from groundline up about 15 inches until the solution puddled at the base and soaked into the root zone. Conventional basal posted 90% control with a herbicide cost per acre of $11.87. Cost per killed plant: 10 1/2 cents. This treatment was the slowest: 63 minutes to treat an acre with 125 plants.
For the low-volume basal application, Hale used a mix of 15% Remedy and 85% diesel. He sprayed each stem from groundline up 12 to 15 inches, only lightly wetting the stem, not to the point of runoff. The low volume basal treatment posted the highest control: 94%, with a herbicide cost per acre of $10.02. Cost per killed plant: 8 1/2 cents. Hale calculated the method
required 52 minutes to treat an acre with 125 plants.
“With huisache and all those thorns, it’s hard sometimes to get in under there with a basal treatment,” he says.
“The foliar spray is easier. On our tour, some ranchers thought it would take longer to foliar spray because of the coverage needed, but it didn’t. And this was done with a backpack sprayer. I think a four-wheeler might cut the time in half.
“This hand-applied foliar application with Grazon P+D is a breakthrough - a way to get effective control and keep the cost down,” Hale says.
You can probably afford to control huisache, too. As part of the demonstration, Hale set up grass cages and took four clippings to monitor grass production through the year.
“This was on improved coastal, which probably yields two to four tons per acre per year,” he says. “Based on our analysis, brush control yielded an extra 2,300 pounds of forage per acre. On a pasture like this, you could probably increase grass production by one-fourth to one-third with brush control.”
*Trademark of Dow AgroSciences LLC. Grazon P+D is a federally Restricted Use Pesticide.
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