and have shown a relation between fungus 

 infection and water salinity in the produc- 

 tion of sago pondweed. In growth studies 

 in sandy soils, sago pondweed, widgeon- 

 grass, and claspingleaf pondweed produced 

 the greatest volume of vegetation at the 

 highest salinity level (17 percent of sea 

 strength) and wild celery and southernnaiad 

 at the lowest salinity level (2 percent). The 

 greatest production of nitella was at an 

 intermediate level. 



Studies were begun in the coastal marshes 

 of Louisiana to develop more rapid and 

 reliable methods for measuring waterfowl 

 utilization of wintering habitats. The most 

 promising results have been obtained from 

 a sampling systenn based on aerial counts 

 along randomly selected transects within 

 the different ecological and management 

 units. 



Management of aquatic plants . --One 

 phase of waterfowl habitat management is 

 the control of noxious aquatic weeds, 

 methods for which are being studied by 

 biologists of the Patuxent Wildlife Research 

 Center. 



A 1961 survey of Eurasian waternnilfoil 

 in the Chesapeake Bay area showed that 

 100,000 acres were infested, an increase 

 of more than 50,000 acres from I960. 

 History of the increase is shown in the 

 records of sampling stations on the Sus- 

 quehanna Flats. None of the stations was 

 infested in 1957, 1 percent in 1958, 47 per- 

 cent in 1959, 84 percent in I960, and 88 

 percent in 1961. Eurasian waternnilfoil 

 rapidly chokes out waterfowl food plants 

 and interferes with boating, swimn-iing, and 

 fishing. Infestations have been found in 

 fresh and brackish waters from New York 

 State to North Carolina and Tennessee. 

 The ability of floating fragments to root 

 and the capability of plants to survive in 14 

 to 16 feet of water help explain the rapid 

 spread of this species. It generally does 

 not grow along shorelines exposed to con- 

 stant wave and tidal action. 



Cooperative studies with the State of 

 Maryland have shown that 2,4-D can pro- 

 vide effective control in tidal areas. Best 





Studying waterfowl foods in the San Luis Valley, south- 

 central Colorado~R.A. Ryder photographed as a 

 graduate student of Colorado State University where 

 he was associated with the Colorado Unit. 



(Photo by Lee E. Yeager.) 



methods and seasons of application are 

 now being developed for a variety of site 

 conditions. 



Alligatorweed, another plant of concern in 

 waterfowl habitat management, is ecologi- 

 cally versatile. It grows in upland fields as 

 well as in ponds and waterways throughout 

 the Southeast. Sources of reinfestation, 

 therefore, are always at hand. 



Experiments in water-level manipulation 

 showed that growth of rooted plants was set 

 back by drops in water level and stimu- 

 lated by rises. Tests of methods for chem- 

 ical control of alligatorweed showed that 

 rooted growth can be controlled by a single 

 application of silvex granules during the 

 active growth period of the plants. Single 



