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November 13, 2006

Later, Alligator

Extension team members tackle alligatorweed from a canoe
Extension team members tackle alligatorweed in Eastern North Carolina waterways. (Photos courtesy Diana Rashash)

It clogs waterways and backs up irrigation ponds. Wildlife get tangled in it, and it does a number on boat propellers. Worst of all, it grows out of control – like, well, a weed. It is a menace, and true to its name, alligatorweed takes a real bite out of eastern North Carolina’s waterways.

“We’ve declared war!” says Diana Rashash, Cooperative Extension area specialized agent in Onslow County.

Rashash has teamed with Wayne Batten, Extension director in Pender County, who launched the first attack on alligatorweed last year. Also on board are the North Carolina Division of Water Resources, the city of Jacksonville, Camp Lejeune Marine Corps Base and New River Air Station.

A perennial, mat-forming aquatic plant, alligatorweed causes debris build-up, which further impedes water flow and invites mosquitoes. According to Batten, large stretches of streams in Pender County have become impassable to paddleboats and fishermen, and water quality issues such as oxygen content are serious concerns.

“Alligatorweed is like Mickey Mouse’s broom in ‘The Sorcerer’s Apprentice,’” Rashash describes. Like the multiplying broom that wreaked havoc in the Disney classic, alligatorweed reproduces from fragmentation, so any attempt to cut it back is futile, Rashash explains. It just keeps growing.

Chemical control isn’t a good option either, because most of it harms other plants, Batten says. In early 2005, Batten worked with Mike Linker, CALS professor of crop science and Extension specialist, to write a proposal for an Integrated Pest Management grant for biological control of alligatorweed. His method of choice: the alligatorweed flea beetle.

alligatorweed flea beetle
Alligatorweed flea beetle.

Native to Africa, the beetle is alligatorweed’s natural predator. It also has proven to work well in Florida, and Batten’s hope is for similar results in North Carolina.

Batten won the $6,861 grant from N.C. State, and in May 2005, released about 6,000 beetles in select Pender County waters. The beetles were donated by the Army Corps of Engineers in Florida, who were conducting similar experiments there and planned to use North Carolina data to supplement their work. It’s a nice partnership, Batten says, “a win-win.”

Batten’s team used GPS to monitor the locations of the beetles and track their “attack” on the weed. The results were mixed. In a few sites, nothing happened, and Batten figures the beetles fell victim to hungry birds, or were killed by chemicals sprayed to control mosquitoes.

But, in many other cases, the beetles conquered the weed.

“One of our local nurseries had a big problem with alligatorweed, and 40 to 50 percent of their irrigation pond was covered with it,” Batten says. “Now, after the beetle release last year, there’s not a single sprig.”

These results inspired Batten to apply for a second year of grant funding, and to take a regional approach to combat the weed.

This year, the Cooperative Extension offices of Onlsow and Pender counties received a $9,730 Integrated Pest Management grant from N.C. State. And, Florida kicked in another supply of free beetles.

“This is the first time we’ve coordinated our efforts to take on alligatorweed – county, city, state, military bases and volunteers,” Rashash says. “We’re all dealing with the same problem, and it’s been a great partnership.”

Rashash’s group alone covered a 20-square-mile area in Onslow County at the same time that the others were releasing beetles throughout Pender County and Camp Lejeune. In all, they released 11,000 beetles over 50 acres in May.

So far, the results are promising. In many spots, the beetles have made the weeds “look like swiss cheese,” Rashash says. In others, the teams are supplementing the beetles’ work with environmentally-friendly herbicides.

“We’re looking now at the possibility of expanding into other counties,” Batten says. “They’re having similar problems with alligatorweed in northeastern North Carolina, and we’d like to continue this collaborative approach for grant funding. Our ultimate goal is to get rid of alligatorweed in all these places.”

Rashash agrees, adding, “The weed is an issue from Brunswick County right on up the coast. Coordinating the efforts of Extension and our various partners will give everyone a bigger bang for their buck.”

- S. Stanard

Posted by Suzanne at November 13, 2006 03:04 PM