Febrararly IS62
Industrial Wastes Controlled pollution is the best method known to date for eradicating large areas of aquatic plants bg Eamld R, Murdock
A
EUSH growth of
aquatic plants in unpolluted waterways is not always a blessing. For recreational purposes, such as boating, swimming, and fishing, the dense submersed plants interfere despairingly. Often such luxuriant growth creates large, stagnant water areas which breed malaria mosquitoes. The coastal waters of the southern states are particularly bothered with water weeds which interfere with navigation. Then again reservoirs impounding municipal water supply are troubled with prolific growths of algal fungus which reduce the water storage capacity and impart undesirable odors and tastes to drinking water. Many schemes have been advanced for controlling the profuseness of underwater plant growth, such as mechanical cutting with a mowing machine device attached to a boat. Mechanical procedures are only temporary expedients for the plant roots are not destroyed and mowing has to be repeated over and over again for many square miles of water area. Furthermore, the bulky, dead cuttings of the plant should be removed from the water; otherwise, it provides a fertile mulch to aid further plant growth. Controlled pollution is the best way to solve this problem. A chemical which would selectively destroy the roots of the troublesome aquatic plant, but not injure fish or other animal and plant life in the treated water, would provide a convenient means for control. Such chemicals while known are not, proved, and the cost of the chemical or the application is prohibitive today except for use in special purpose small lakes. Vegetation growing in watercourses can be conveniently divided into three groups. Vegetation which grows entirely under the surface of February 1952
the water is referred to as subEicher ( I ) obmersed plants. Those having broad tained interesting data from leaves or blossoms floating on the the use of nigrawater surface are semisubmersed sine dyestuff in plants. The third group of weeds controiling weeds differ by having thick, woody stems in two Arizona The which permit them to extend l a k e through the water surface. These rents n a t uin r athe l clake u r - 'ere helpful in disare referred to as erect plants. tributinp: the dye which was added Quite naturally, the recent de- 10 pou
