continue to reduce the regrowth of established trees as well as the growth of seedling saltcedar plants. As the beetle larvae consume all of the leaves, more sunlight reach- es the soil encouraging growth of grasses and other more desirable vegetation. Defoliated trees stop blooming which eliminates seed production, reducing the threat of saltcedar re-invasion.” The use of insects for saltcedar
control and all U.S. biological con- trol programs are regulated under the National Environmental Policy Act and the USDA-Animal and Plant Health Inspection Service (APHIS). Exotic insects can be released only if they have been approved by APHIS and the participating state.
Other control options Options for controlling saltcedar
other than biological are chemical and mechanical. Herbicides can be used for both individual plant treatment (IPT) and broadcast ap- plications. If applied properly, leaf sprays are effective either applied broadcast or by IPT. Plants have to be completely covered with spray for effective control, because any part left untreated will probably survive. For broadcast applications, use at least 10 gallons per acre total spray volume with a surfactant. “Tank mixing imazapyr and
gly phosate is a good choice for younger stands, with trees gener- ally up to 10 or 12 feet tall, and 2- to 3-inch trunk diameters,” said Hart. “Imazapyr used alone is usu- ally required for good control of older, taller and larger diameter saltcedar trees at high densities per acre. Research has shown that saltcedar is most susceptible to fo- liar applications of imazapyr in late summer to early fall, generally from late July through September.
62 The Cattleman May 2013
Because imazapyr is a very slow- acting compound, you will not see results from applications until the next spring. Saltcedar in standing water is much harder to kill and control rates are reduced.” Another effective treatment for
young, smooth-bark plants is the basal stem spray method with tri- clopyr (Remedy™) mixed with diesel or vegetable oil. You can also use this mixture to treat stumps imme- diately after cutting. These treat- ments work best when applied dur- ing the growing season and when plants have mature leaves. “Mechanical control of saltcedar
involves grubbing techniques that can be somewhat successful if you take care to extract the entire crown and root portions,” explains Hart. “This treatment method is very expensive and can be limited by topography. Don’t use mechanical control methods to remove standing debris following herbicidal control until a minimum of 2 years after initial treatment.”
Beetles are moving and eating “Saltcedar leaf beetle numbers
and impact were increasing at many locations across the state in 2012,” reported Dr. Mark Muegge, Texas A&M AgriLife Extension Entomolo- gist at Ft. Stockton. “The Tunisian species is now well established and dispersing at many locations on the upper and middle Pecos River. On the Pecos, beetles have defoliated all visible saltcedar from Iraan to Red Bluff Reservoir and have dis- persed along the river for at least 140 river miles in 2012. Further south, the Tunisian beetles again defoliated essentially all of the salt- cedar along more than 250 miles of the Rio Grande River from Fort Hancock to the eastern side of Big
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