Study finds Roseau cane scale has not attacked crops or grasses

Tobie Blanchard

LSU AgCenter scientists conducting research on roseau cane scale, an insect that may be causing die-offs of roseau cane in marshes along the Louisiana coast, said a recent study showed this insect has not attacked commercial crops or marsh grasses important to Louisiana.

Leslie Avilés, an entomology graduate student, conducted greenhouse and field studies on 17 types of grasses, including sugarcane, corn, rice, sorghum, smooth cordgrass and California bulrush, and found that the scale was not a threat to these grasses and appears to be restricted to roseau cane.

Avilés planted stems from each individual grass in containers and added a stem of roseau cane heavily infested with the scale and tied the stems together. She also included scale-free roseau cane in a container with infested cane as the control.

After a month she checked the stems for infestations and found crawlers, which are the first generation of the scale, on bulrush and cordgrass. The crawlers had attempted unsuccessfully to settle on those native grasses but did not mature into adulthood. No crawlers were found on the commercial crops.

Avilés also went to the mouth of the Mississippi where heavy infestations are found to see if the scale was infesting native grasses in the marsh.

“We found native grasses growing next to heavily infested roseau cane,” Avilés said. “We peeled back hundreds of samples from several species of marsh grasses and searched for the scale but didn’t find any.”

These results are good news for Louisiana farmers and for the Louisiana Department of Wildlife and Fisheries, which uses smooth cordgrass and bulrush in coastal restoration projects.

Tobie Blanchard is the assistant director of LSU AgCenter Communications and the communication coordinator of the LSU College of Agriculture.

(This article appears in the fall 2018 issue of Louisiana Agriculture.)

Read: “Roseau Cane Die-offs Threaten Louisiana Coast.”

Leslie Aviles in field.jpg thumbnail

Leslie Avilés, and LSU graduate student in entomology, inspects roseau cane that is part of an experiment she conducted at a greenhouse on the LSU campus. She was looking to see if roseau cane scale, a pest that infests the cane, would spread to commercial crops or marsh grasses. Photo by Tobie Blanchard

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A close-up of roseau cane scale along with the parasitoid wasp, Neastymachus japonicus, which was introducted along with the scale. Photo by Rodrigo Diaz

12/13/2018 3:42:56 PM
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