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Scientists to Map Battle Plan Against Aquatic Weed

By Sean Adams
March 17, 1997

Scientists from around the world will gather at a meeting March 18-19 in Washington to develop an environmentally friendly battle plan against a weed that infests millions of acres of lakes, streams and rivers around the world.

The researchers will meet at the World Bank Building for a two-day session to devise a biological control strategy for controlling the water hyacinth, a floating aquatic weed that is considered one of the top 10 noxious weeds worldwide. It is difficult to eradicate because of its rapid growth rate of one percent a day. At that rate, a single water hyacinth plant in a 60-acre tropical lake would cover the entire lake in one growing season.

The weed has become a particularly serious problem in third world countries that have not been able to control it with herbicides or mechanical cutting. At the meeting, organized by the U.S. Department of Agriculture and the World Bank, many of the world’s leading researchers on the weed will form an international consortium to develop recommendations for controlling water hyacinth. They will focus on sustainable biological control methods such as naturally occurring insects that feed on the weed and keep it in check.

In the 1960s and 70s, scientists with USDA’s Agricultural Research Service and the U.S. Army Corps of Engineers studied biological control of the water hyacinth in its native area, the Amazon Basin of South America. There, the weed is not a problem because it is held in check by its natural enemies.

Later, several insect species from South America were introduced in the United States to control the weed, which was released in New Orleans in 1874 and rapidly spread in the absence of natural enemies. In Louisiana, two weevils from South America were effective at cutting back water hyacinth infestations from a high of 1.8 million acres to about 200,000 acres today.

But in other parts of the world, the weed is spreading faster than new biocontrol agents can be deployed. So scientists will identify and develop new insects and natural disease organisms for the weed. They’ll also work on ways to increase the supply and distribution of these agents around the world, and to transfer the technology to weed control personnel.

There is no registration fee for the meeting, which begins at 8:30 a.m. on Tuesday, March 18. The meeting is scheduled to be held in rooms H1-200 (Tue.) and H2-300 (Wed.) at the World Bank Building, 600 19th Street NW. At the front door, reporters should tell the guard they are attending the Water Hyacinth Meeting and they will receive a pass.

Scientific contact: Neal R. Spencer, USDA/ARS Northern Plains Agricultural Research Laboratory, Sidney, Mont., phone (406) 482-9407,; Raymond I. Carruthers, USDA/ARS National Program Leader, Biological Control, Beltsville, Md., phone (301) 504-5930,