WATERHYACINTH 47 



states that "The wildlife crop these weeds destroy each year in 

 Louisiana is valued at $14,727,000." It has been estimated that 

 the total annual loss to Louisiana agriculture, fish and wildlife, 

 navigation, drainage, and public health amounts to nearly 38 mil- 

 lion dollars. Because of this economic drain, efforts are being 

 made to reduce or eliminate waterhyacinth on thousands of acres 

 of its present range. 



CONTROL 



Herbicidal treatment has proved so effective on waterhyacinth 

 that mechanical methods employed formerly have been largely 

 abandoned. The plant can be killed rather readily by light or 

 moderate dosages of 2,4-D formulations except where floating 

 mats are so dense that herbicide spray does not penetrate into 

 lower layers. 



Recommendations resulting from experiments conducted co- 

 operatively in Louisiana, 1948-50, by the Boyce Thompson Insti- 

 tute, the Corps of Engineers, and Tulane University, included the 

 following: Use of the alkanol amine salt of 2,4-D (for combined 

 economy and low hazard to crops) at 8 pounds of acid equivalent 

 per acre; spray concentration of 1.2^ and 80 gallons of solution 

 per acre in low-pressure spraying; in high-pressure treatment 

 from a helicopter, 2 gallons per acre of the 8-pound acid equiva- 

 lent formulation direct from the drum. Most effective killing and 

 sinking of treated plants was found to occur in the period of rela- 

 tively slow growth, from August to March. 



Current practice in waterhyacinth control deviates consider- 

 ably from the above recommendations. The amount of acid 

 equivalent actually applied per acre in current control programs is 

 as low as 1 or 2 pounds, the operators believing that these amounts 

 are effective and adequate. The Research Committee of the South- 

 ern Weed Conference has recommended (1957) use of "1 to 4 

 pounds of 2,4-D acid equivalent in 2 to 150 gallons of water" for 

 waterhyacinth control. 



In recent years, the Florida Game and Fresh Water Fish Com- 

 mission cleared more than 20,000 acres of waterhyacinth infesta- 

 tion on lakes and ponds in the State. This was done on a coopera- 

 tive basis in which the landowners paid costs of chemicals, 

 amounting to about $3 per acre, and the Commission footed the 

 rest of the bill which was about $5. Aerial applications were 

 made with a V^-gallon per acre of a 3.34 pounds acid equivalent 

 ester formulation of 2,4-D, and treatments from boats (mainly 

 airboats) involved % gallon per acre of a 4 pounds acid equivalent 



