large numbers of adventitious (false) roots, floated up in large 

 masses to the surface and was carried ashore by the wind. These 

 objectionable accumulations of vegetation had to be removed from 

 the beach. The loosening of weeds at the bottom was characteristic 

 of Shongun Lake and Dixon's Pond, also located at Boonton, New 

 Jersey. In the former, long shoots of Cabomba (fanwort) , 12 feet 

 or more in length, drifted to the windward side of the lake, where 

 they were finally removed with forks . 



Chemical Control of Submersed Plants 



During the past several years, many new chemicals have been 

 tried for control of submersed aquatic plants. Several of these have 

 proven effective, but such promising herbicides as Diquat, Silvex, 

 Endothal, S.imazine, Hyamine 1622, and granular 2,4-D need more 

 extensive field testing before their true value is known. Cost 

 is another very important consideration. Considering these factors, 

 sodium arsenite continues to be the most economical and certain of 

 satisfactory results. A few of the promising new herbicides are 

 listed below. None are known to be harmful to man or livestock. 



Diquat (FB.2) 



Diquat (1 ,1 'ethylene-2 ,2 '-dipyridylium dibromide) is one of 

 the most promising of the newer chemicals, but it is expensive, 

 costing about $7.00 per pound. Bond observed that it would kill 

 Elodea densa at one p. p.m. The 48 hour TLj^ for chinook salmon 

 fingerlings was 28 p. p.m., so it is apparent that its safety margin 

 in toxicity to fish is highly satisfactory. Blackburn (1961), in 

 a personal communication, reported that he obtained 100 per cent 

 control of southern naiad ( Najas guadlupensis ) in laboratory ex- 

 periments at 2.5 p. p.m. and good control in a field experiment in 

 a non-flowing Florida ditch at 3.0 p. p.m. 



Endothal 



Experiments by Charles R. Walker, Missouri Conservation 

 Commission 2.' with Endothal Weed Killer (2 pounds active ingredient 

 per gallon) showed that 10 pounds per acre (1.0 p.p.m.)were adequate 

 to control coontail ( Ceratophyllum demersum) through an entire 

 season. Najas f lexilis was controlled through a four-month period 

 by 2.0 p. p.m. of the same liquid formulation. 



Granular formulations of sodium endothal (5 per cent active 

 ingredient) gave 90 to 100 per cent control of Potamogeton americanus 

 at 5.0, P. diversifolius at 0.5, P. foliosus at 5.0, P. pusilus at 

 1.0 parts per million, respectively. Pounds per acre applied 

 ranged from 5 pounds to 50 pounds . 



ll Data furnished through the courtesy of the Missouri Conservation 

 Commission was obtained by their Dingell-Johnson Project F-l-R-9. 



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