In the soft, pre-dawn light, the shaggy beasts known collectively as the Texas State Bison Herd are on the move.
Within the bounds of 14,000-acre Caprock Canyons State Park near Quitaque, Texas, they go pretty much wherever they want.
This morning, trudging from Lake Theo through the adjacent picnic grounds to pasture, they pause occasionally to graze green native grasses or nip the brown leaves of dying mesquite trees. Like many southwestern pastures, this one is under attack from mesquite.
Like many southwestern ranchers, the Texas Parks & Wildlife Department (TPWD) is hand-spraying the mesquite to stop the encroachment.
“Our ultimate goal is to have this park look like it did before settlement 300 years ago,” says Park Superintendent Donald Beard.
That would have been a mixed prairie of short, mid- and tallgrasses. The native redberry juniper, mountain (blueberry) juniper and mesquite would have been confined to slopes and bottoms where fire couldn’t reach them, he says.
The park has used fire in the past to suppress the brush, and it was effective on seedlings. But as mesquite gets bigger, fire tends to kill the above-ground portion and leave the bud zone alive in the soil. That bud zone then resprouts with more live stems than before.
Beard says the better plan now is to spray the mesquite and then follow up with fire a few years later to maintain control.
So, in 2013 and 2014, he accelerated brush control in the park using Sendero® herbicide to hand-spray the mesquite leaves.
Available in Texas, Oklahoma and New Mexico, Sendero has earned its moniker as The new standard in mesquite control.™ It has delivered a higher degree of rootkill than older chemistry and yields more consistent results. The herbicide also is quite selective in what it controls, which is good for TPWD goals.
“The selectivity of Sendero is why I’m able to do this,” Beard says. “From what I can tell, Sendero doesn’t even control Maximillian sunflower. It makes it sick for a while, but it comes back.”
The mix Corteva Agriscience™ recommends for hand-spraying mesquite is a mix of 1 percent Sendero, ¼ percent surfactant and ¼ to ½ percent of a spraymarking dye.
Hand-spraying the leaves works well on mesquite up to 6 or 8 feet tall, the practical limit for getting thorough coverage of herbicide on all the leaves.
For bigger trees, the park uses a shredder mounted on a skid-steer that reduces a tree to mulch. Workers then apply a mix of Remedy® Ultra herbicide and basal oil as a cut-stump treatment to prevent resprouting. The labeled mix is 25 percent Remedy Ultra and 75 percent basal oil.
Beard initially focused efforts on what had been the only bison pasture, 1,000 acres of former cropland sown to native grasses. Later, TPWD released the bison to the rest of the park. Strategic brush control may follow them.
TPWD tagged some of the cows with GPS (Global Positioning System) collars to track their movement.
“We’ll see what areas they prefer, and we’ll focus there,” Beard says. “And we’ll look at soils and where we can grow better grasses to increase our carrying capacity.”
Beard also wants to target dense brush along canyon rims that now block spectacular views.
To accomplish all he wants to do, at least in the near term, may require more than hand-spraying. So he’s also looking at the possibility of spraying Sendero® herbicide by helicopter.
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™®Trademarks of Dow AgroSciences, DuPont or Pioneer, and their affiliated companies or their respective owners. Always read and follow label directions. Sendero is not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. State restrictions on the sale and use of Remedy Ultra apply. Consult the label before purchase or use for full details. Always read and follow label directions.
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