AP NEWS

LSU works to help control invasive water weed in Puerto Rico

May 11, 2019

BATON ROUGE, La. (AP) — Louisiana State University is working with a private citizen and a university in Puerto Rico to control an invasive South American weed that can quickly form dense mats over waterways.

Recovery from Hurricane Maria, which hit the island in 2017, leaves Puerto Rico with few resources to fight giant salvinia, and it’s important to bring back freshwater habitat, LSU AgCenter entomologist Rodrigo Diaz said in a news release Friday.

The fast-growing aquatic fern can form thick mats that choke aquatic life and hamper swimming and boating. It can double the area covered in as little as a week, and tiny eggbeater-shaped “hairs” on the nickel-sized leaves let them shed liquid droplets, making the plant hard to kill with herbicides.

Giant salvinia has overtaken a lake southeast of San Juan and Daniel Diaz, who lives on Lago Las Curias, got in touch with the AgCenter after looking for ways to control it.

For more than a decade, the AgCenter’s been raising flea-sized salvinia weevils, which feed on the plant and kill it - and don’t eat anything else.

The AgCenter and University of Puerto Rico entomologist Jose Carlos Verle Rodrigues are working to get permits to export the weevils to Puerto Rico.

Weevil-infested salvinia has been set out in salvinia-infested lakes, canals and bayous around Louisiana. However, cold winters kill the weevils, so more heavy containers of the infested weed must be hauled in and deployed around a waterway to keep salvinia under control.

“That shouldn’t be a problem in Puerto Rico,” said Charlie Wahl, an AgCenter entomology research associate who will bring the weevils to the island once the project is approved. He has extensive experience in rearing and releasing the weevils in Louisiana and monitoring their effect on salvinia.

Wahl said there is a strategy for placing the weevils, and he will help show how to use them most effectively.