Aquatic Vegetation and Control Measures 177 



chase of lots for permanent homes on small lakes should insist on a 

 sewage system which \\ ill carry all effluents away from the lake. 



Dense stands of vegetation, besides being a nuisance, offer too much 

 protection to small fishes, and are sometimes directly responsible for 

 overpoj^ulation and stunting. This is true not only for submersed vegeta- 

 tion, but also for emergent forms such as cattails, bulrushes, arrowheads, 

 water willow and pond lilies. For these reasons, where economically 

 justifiable, excessive aquatic vegetation should be controlled. 



Control of Higher Aquatic Vegetation 



For more than 30 years, sodium arsenite was used for the control of 

 submersed rooted aquatic vegetation, often with good results.^'^ The main 

 objections to its use are that ( 1 ) it is a poison which may accumulate in 

 a pond or lake; (2) it is dangerous to handle and apply; (3) it is not very 

 effective in the control of certain water weeds, such as sago pondweed, 

 Potamogeton pectinatiis, and curly-leaved pondweed, P. crispus. 



Recently many terrestrial herbicides have been tested for their potential 

 usefulness in aquatic weed control. ^^ Not only must these herbicides kill 

 aquatic plants, but they must also show low toxicity to fish and aquatic 

 invertebrates. For example, CMU [3-(p-chlorophenyl)-l,l-dimethylurea], 

 a terrestrial soil sterilant was found to control Najas in ponds when 

 applied at a rate of 15 pounds per acre.^^ This material was nontoxic to 

 fish and most aquatic organisms. 



Some of the more promising herbicides are given in Table 6.5.^^ How- 

 ever, progress in this field is so rapid that it is probable that new and more 

 efficient herbicides will soon replace some of these listed in Table 6.5. 



LITERATURE 



1. Anon., Jour. Wildlf. Mgt., 14( 1 ), 85-88 ( 1950) . 



2. Applegate, V. C, Howell, J. H., Hall, A. E., Jr., and Smith, M. A., U. S. 

 Dept. of Int., Fish ir Wildl. Serv. Special Scientific Report, 207, 157 pp., 

 (1957). 



3. Ball, R. C, Am. Fish. Soc. Trans., 78, 146-155 (1950). 



4. Ball, R. C, Jour. Wildlf. Mgt., 16(3), 266-269 (1952). 



5. Ball, R. C, and Tanner, H. A., Mich. St. Coll. Tech. Bull, 223, 1-32 

 (1951). 



6. Beall, H. B., and Wahl, R. W., Prog. Fish-Cult., 21(3), 138-142 (1959). 



7. Beckman, W. C, Am. Fish. Soc. Trans., 70, 143-148 (1941). 



8. Bennett, G. W., Ill Nat. Hist. Surv. Bull, 22(3), 357-376 (1943). 



9. Bennett, G. W., Ill Nat. Hist. Surv. Bull, 24(3), 377-412 (1948). 



10. Bennett, G. W., North Am. Wildlife Conf. Trans., 19, 259-270 (1954a). 



11. Bennett, G. W., Ill Nat. Hist. Surv. Bull, 26(2), 217-276 (1954b). 



12. Bennett, G. W., and Childers, W. F., Jour. Wildlf. Mgt., 21(4), 414-424 

 (1957). 



