Controls for Sting Nematodes

Larry Duncan provides updates on the damage done by sting nematodes and research into controlling them with nematicides and perennial peanut as a cover crop. Duncan is a University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) nematologist at the Citrus Research and Education Center.

Sting nematodes have become a “real issue” for Florida growers in the past five or six years, Duncan says. He explains that with HLB, growers are repeatedly having to replant non-productive groves. Young trees in those new plantings are highly susceptible to sting nematodes that eat at the root tips. And growers are well aware that HLB itself reduces tree root systems significantly.  

Duncan adds that growers who used to disk weeds have been mowing them in recent decades. With the mowing, native plants that grow in row middles “tended to be hosts for the nematode,” he says. “And so all of a sudden, for the first time in Florida history really, the row middles were just full of sting nematodes that had been more or less managed by disking in the past.”

“You can control the (sting) nematode in the tree rows with nematicides,” Duncan says. “In the row middles, however, it would be too expensive to use nematicides.” Consequently, researchers are looking into ways to control the nematodes in the row middle with a non-host plant.

The sting nematode non-host plant being researched is perennial peanut. Research has shown that a perennial peanut cover crop can reduce sting nematode populations by up to 98 percent. But, Duncan says, “it’s tricky to get established.” The problem with establishment is keeping weeds that are hosts for sting nematode from growing along with the peanut. It can take three to four years to establish the perennial peanut crop from rhizomes, he says.

Duncan says virtually no new nematicides have been created for agriculture in the past three or four decades, and some old nematicides are no longer available. But some new, safe, highly selective products have been developed in recent years, and researchers are studying their efficacy.

This interview with Duncan is featured in the October All In For Citrus podcast, a joint project of UF/IFAS and AgNet Media. Listen to the full podcast here.