Texas farmers battle host of insects

AMARILLO, Texas – Texas Panhandle farmers are battling a host of insects in a variety of row crops, according to Carl Patrick, entomologist with Texas Cooperative Extension.

Right now, spider mites are causing some early problems in the edges of corn and sorghum plots. Corn borer flight is also under way. Thrips are present in area fields.

“Spider mites are making their presence known early this year,” Patrick said.

Above-average temperatures and dry, windy days in May significantly added to the current mite situation. Dryland wheat in center-pivot corners or near corn fields quickly matured.

“This situation forced the mites, commonly found in wheat, to rapidly seek alternate hosts, namely corn and sorghum. They arrived earlier and in greater numbers than usual,” Patrick explained.

In many area fields, miticides have been applied to suppress the developing infestation. But selecting the right compound is important.

“Miticides with broad spectrum activity should not be the first choice,” the entomologist advised.

For corn growers, the western corn rootworm is another nuisance already out in various sizes. Patrick scouts fields across the region and uses the corn rootworm developmental model data generated by the North Plains Potential Evapotranspiration Network to monitor the pest’s progress.

Crop rotation, at-plant insecticides, immediate treatments for crop rescue, or rootworm-resistant corn varieties are tools that hopefully have minimized any loss to western corn rootworm, Patrick said.

“Beetles will soon emerge and start feeding on leaves. But the damage is of little consequence,” he said.

Controlling beetles in refuge areas near fields where rootworm-resistant corn grows also helps reduce next year’s populations. Patrick advises farmers who decide to use insecticides in such spaces to apply treatments at the same time and manner used for rootworm-resistant acres.

Growers also are seeing southwestern and European corn borer moths active at this time. The moths are laying eggs that produce the first generation of borers. Reports from the South Plains show second and third phase larvae feeding in plant whorls.

The good news is that first-generation corn borers seldom reach economic infestation levels justifying an insecticide application. Little or no damage from these borers is expected on Bt corn.

But spider mites aren’t satisfied with one crop host.

“Right now, the mites are showing up in sorghum, particularly seed-production sorghum, for the same reasons they hit corn,” he said. A limited miticide arsenal for sorghum and sensitivity of certain sorghum lines to miticides make management decisions difficult, Patrick said.

Propargite seems to be the compound of choice. However, the miticide may damage the plant if too much of it becomes concentrated in the stalk area, which can happen after a rain or irrigation, for example.

At some level, thrips are also infesting all area crops. However, the biggest concern is their build-up in cotton, Patrick said. The crop is thriving in warm temperatures, but thrips can still cause a problem.

“Thrips often go for the small folded leaves in the growing end of the plant. The pest can be overlooked, if plants aren’t closely inspected,” Patrick said.

The numbers of thrips per plant, used as treatment indicators, increases as the plant adds more leaves. Control may be justified when the thrips equal the number of true leaves present at the time of inspection, particularly if immature thrips are present. Insecticide application is rarely warranted once plants reach the five to seven true-leaf stage.

Panhandle producers count on Patrick’s seasonal pest reports to make key management decisions. The information is widely used by Panhandle Extension agents and area specialists, in addition to certified crop advisers.

A full complement of small grains and cotton production information, including insect problem issues, is available on the Internet at: http://txipmnet.tamu.edu/crops

Pam Dillard writes for Texas A&M University. e-mail: [email protected]

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.