WATERCHESTNUT 45 



50 gallons of #2 fuel oil per acre. In a limited part of the Gun- 

 powder River infestation, the Maryland Board of Natural Re- 

 sources appears to have obtained good results in 1955 (under re- 

 portedly ideal spraying conditions) v^^ith amine salt at the rate of 

 about 2 pounds acid equivalent per acre in 25 gallons of v^^ater 

 containing a detergent. Recently, however, the poundage has 

 been increased. 



Follow-up control within the same season may be necessary. 

 Spray is likely to be less effective on foliage which is largely 

 under water as in sparse stands or when waves wash over the 

 rosettes. Airboats have proved useful for travel over beds dur- 

 ing spraying operations. 



MOWING 



Cutting stems about a foot below the water surface can be 

 very helpful in suppressing waterchestnut infestations. Hockney 

 underwater mowers or other types of equipment, including sickles, 

 can be used for the purpose. Mowing should begin early in the 

 season, about the time small rosettes appear at the surface. Cut- 

 ting at this time is easier and may involve less regeneration. At 

 least one follow-up mowing is likely to be necessary within the 

 same season. Mowing after the rosettes have begun to set seeds 

 is not likely to be worth while since some seeds may have already 

 dropped to the bottom and others can mature on drifting rosettes. 

 In small operations it may be possible to remove cut rosettes and 

 destroy them, but in larger operations this is not practical. 



REFERENCES 



1955. Experimental Control of Water Chestnut {Trapa nalans) in New York State. 



Ralph H. Smith. New York Fish and Game Jour. 

 1955. Water Chestnut Threatens Disaster to Maryland Water Areas. Maryland 



Tidewater News, 12 (1). 

 1955. Another Waterchestnut Infestation. Alexander C. Martin. Jour. Wild. 



Mgt., 19 (4). 

 1950. Water Chestnut Control Project Report and P-R Quarterly Reports on Projects 



10-Dl, 2, and 3, Massachusetts Dept. Cons. 

 1949. Potomac River and Tributaries at and below Washington, D. C. ; Ehmination 



of Waterchestnut. 81st Cong. House Document 113. 

 1949. (approximately). Danger: The Water Chestnut. State of New York, Dept. 



of Cons. 



