Scuttling Water Hyacinths
A hundred years ago, Florida was fighting an alien invaderand losing.
The New York Sun reported a prolific blue-green plant was obstructing the
St. John's River, stopping boat traffic cold for miles. It quoted panicked
skippers trying to ferry food and supplies back East, who were immobilized by
huge mats of water hyacinth. Meanwhile, state officials were demanding federal
Despite the advent of chemical herbicides, the weed still had a grip on
120,000 acres of Florida's waterways in the 1960's. It was blocking barges and
depleting water oxygen levels, choking the fishing industry. It was also
creating a flood hazard.
"We have a photo from the 1960's of boats trapped in a fish camp at
Lake Rousseau, and there are water hyacinths as far as the eye can see,"
says Bill Caton, an environmental administrator with Florida's Department of
Florida's water hyacinth problem today is minor, compared to historical
proportions. While the weed now covers only 1,680 acres of Florida's waterways,
a total of 15,000 acres are sprayed with 2,4-D, sometimes repeatedly, to keep
it that wayat a cost of millions of dollars each year.
The water hyacinth's U.S. invasion began innocently enough, when the plant
was given as a souvenir at the 1884 New Orleans Cotton Exposition. Soon, the
plant was causing problems in that state, too. Louisiana now has over 100,000
infested acres by 1994 estimates.
Biological controls, such as insects that consider water hyacinths a
delicacy, have helped to keep the plant in check in both states. Scientists
with the U.S. Army Corp of Engineers, the State of Florida, and the U.S.
Department of Agriculture are cooperating to obtain these helpful creatures.
As part of their work, researchers with USDA's Agricultural Research
Service quarantine foreign biological controls at the Aquatic Weeds Research
Unit in Fort Lauderdale, Floridato make sure they eat only the right
weedsbefore releasing them into the environment.
ARS scientists, working with ARS colleagues in Buenos Aires, Argentina,
isolated three South American water hyacinth-eating insects: Neochetina
eichhorniae and N. bruchi weevils and a moth, Sameodes
"These insects work as a complement to chemical controls," says
Ted D. Center, a supervisory entomologist at the Fort Lauderdale research
facility. "They can go where sprays can't reach and prevent new
Last year, the United Nations declared international war on the floating
weed, and the UN's Food and Agriculture Organization enlisted an informal team
of scientists, relief workers, and public officials to draft a world protocol
for controlling it.
Not only was Center included in this group, his lab hosted a conference on
water hyacinths that was attended by leaders from Africa, Mexico, and other
"They told us they were interested in biological controls because they
were an affordable adjunct to chemicals," says Center.
In Africa and Asia, the water hyacinth poses special economic threats. Not
only does it hamper boating and fishing, it also damages irrigation systems
used to grow food. People in South Africa named water hyacinths "Florida
Devils" because evidence suggests the plant may have come to that area
from the Sunshine State.
"We got our first Neochetina eichhorniae for release from
USDA-ARS in Florida and our first N. bruchi, also," says South
African researcher Stefan Neser. "We also discovered the apparently quite
damaging Eccritotarsus catarinensis in Brazil and will be making it
available to ARS and our other cooperators."
"Tackling the water hyacinth problem has offered scientists here and
abroad an opportunity to collaborate," says Center. "This cooperative
research has benefited rural communities in the United States and elsewhere
that depend on clear waterways for fishing, recreation, and other
uses."By Jill Lee, ARS
Center is at the USDA-ARS Invasive Plant Research Laboratory, 3205 College
Ave., Fort Lauderdale, FL 33314; phone (954) 475-0541 ext. 103.
"Scuttling Water Hyacinths" was published in the
issue of Agricultural Research magazine.