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New Herbicide Application Method Approved For Managing Sand Shinoak

published: February 4th 2010
by: Kay Ledbetter
source: TAMU Ag Communications

Approval of a new application technology for an herbicide known to control sand shinoak will give land managers more flexibility for when and where they treat, according to a Texas AgriLife Extension Service specialist.

J.F. Cadenhead, AgriLife Extension range specialist from Vernon, said sand shinoak, also called shinnery, is the shorter, shrubby species of oak that typically grows in dense stands in sandier soils in much of the western half of Texas.

Not only can the dense stands of shinnery compete heavily for available rainfall that could produce more desirable and diverse vegetation in pastures, it can also be poisonous to livestock at certain times of the year, Cadenhead said.

Shinnery poisoning usually occurs in the spring when livestock consume many young immature leaves, buds, stems and/or flowers, he said. Consuming as little as 6 percent of an animal’s body weight in dry plant material may be sufficient to cause oak poisoning.

Cadenhead said producers have long had the option to use Spike herbicide for sand shinoak control in range and pastures, but the labeled formulation for these sites was only the extruded pellet, Spike 20P.

Spike 20P had to be spread through some type of special spreader or fertilizer/seeder equipment, he said. Mounting the special spreaders onto ground rigs and/or aircraft was time consuming and costly, and proper calibration of this equipment was difficult.

“A recent development of new application technology for a different formulation of Spike will provide the land manager a method of applying this herbicide himself without having to rely on a custom applicator,” Cadenhead said.

Using the newer formulation, called Spike 80DF (80 percent active ingredient in a dry-flowable granule), a land manager can mix the granules in water and apply the mixture as a spray directly to the ground using straight-stream nozzle tips mounted on a spray boom, he said. No spreader system is needed.

Straight-stream nozzle tips are readily available or a different-sized orifice, such as a No. 6 or a No. 8, can be substituted for other sprayer nozzle orifices so that a straight stream of spray is produced, he said. The size of the orifice needed will depend on the sprayer pump size, sprayer pressure and volume of total spray mix desired.

“This newer application technology allows the land manager to make his own applications when and where he wants them,” Cadenhead said.

The approved application rate of Spike 80DF herbicide for sand shinoak control calls for applying 1 pound of active ingredient (tebuthiuron) per acre, which amounts to mixing 1.25 pounds per acre of the granules in water, he said.

This then can be applied using ground equipment with straight stream nozzles spaced from 3 feet to 6 feet, which will deliver a total spray mix volume of about 20 to 30 gallons per acre, Cadenhead said.

Agitation is important to dissolve and maintain the granular herbicide in the solution during application, he said. Also, it is recommended to use the closer-spaced nozzles when treating high densities of sand shinoak.

It is important to note that grass damage or kill will occur directly under each nozzle and the damage can persist for one to three years following application, Cadenhead said. Applications may be made anytime during the year, but less grass damage may occur when the treatment is applied in the winter when warm-season grasses are dormant.

The optimum period for treatment is from Oct. 1 to April 1, except in the Trans-Pecos region where the optimum period is May 1 to July 1, just before the rainy season, he said.

“This application method should become more popular for opening up areas of dense sand shinnery to provide for growth of a much more diverse stand of forbs and grasses desirable for both livestock and wildlife,” Cadenhead said.

“As always,” he cautioned, “follow herbicide labels and recognize that many of our soil-applied herbicides can and will provide control of non-target plants whose root systems are growing in and adjacent to the area treated.

“Exercise caution when treating around other desirable trees and shrubs, and keep the herbicide application away from non-target trees at least as far as the distance of their canopy diameters.”