Conservation Matters February 2014

The Texas Land, Water and Wildlife Connection

Saltcedar leaf beetles prove vital control to invasive tree

By Katie Heinrich

Beetles used as biological control of the invasive saltcedar tree in West Texas had another successful year in 2013 as large numbers returned despite late spring freezes last year. The saltcedar leaf beetle population numbers continue to increase and disperse in new areas, said Dr. Allen Knutson, Texas A&M AgriLife Extension Service entomologist at Dallas.

Since 2004, when the saltcedar leaf beetles were first established in Big Spring by the United States Department of Agriculture’s Agricultural Research Service and Texas A&M AgriLife entomologists, this biological control strategy for saltcedar has been successful in all of the major watersheds of West Texas, from the riverbanks of the Rio Grande and Pecos to the Upper Colorado and Brazos Rivers and north to the Canadian River in the Texas Panhandle, Knutson said.

There were even reports in October 2013 that the beetles had made their way from the Texas Panhandle into western Oklahoma and north to Kansas, he said.

Beetles are not effective in all areas though, Knutson said. The biological control provided by the leaf beetles requires several years so is a slow method. Where beetles are absent or there is a need for a more rapid control of saltcedar, herbicides and mechanical control are important methods.

Saltcedar invades an estimated 450,000 acres in Texas and often grows in dense thickets along waterways and around reservoirs in West Texas. These thickets crowd out native plants and forage grasses, compete for water and can cause flooding by blocking stream flow. Saltcedar thickets degrade riparian habitats and invade agricultural land enrolled in the Conservation Reserve Program (CRP) managed by the Farm Services Agency (FSA), Knutson said.

Knutson said that in summertime conditions, the beetle larvae will defoliate a saltcedar tree in about 12-14 days by feeding on its leaves and tender bark. The continuous defoliating period every year helps to exhaust the tree’s energy resources, eventually resulting in its death.

The beetles have even been seen to return to prescribed burn areas to feed on portions of saltcedar regrowth, according to Knutson.  

The efforts of the saltcedar biological control team and success of the saltcedar beetles as a control method earned the team the Texas A&M AgriLife Vice Chancellor’s Award in Excellence, awarded in January 2014. AgriLife team members include Knutson; Dr. Jerry Michels, Texas A&M AgriLife Research entomologist, and his research assistant, Erin Jones; and Dr. Mark Muegge, AgriLife Extension entomologist.

See this AgriLife TODAY article for more information on the team’s award.

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