The following fittings are used on the supply lines from the 

 sodium arsenite drums; 3/4 inch pipe, long enough to reach to the 

 bottom of the chemical drum after insertion through the bung, 

 notched at the suction end; 3/4 inch right angle elbow; pressure 

 hose to reach to 3/4 inch gate valve; nipple; reducer 1% to 3/4 

 inch, nipple for connection to a 1% inch 45° Y-branch. 



A larger pump with 2 inch suction and 1% inch discharge, 

 powered by a 5 h.p. gasoline engine has been used with success in 

 large operations. A % inch smooth fire hose was used on the dis- 

 charge end with this pump . 



SUMMARY 



Following the advent of 2,4-D immediately after World War II, 

 many chemicals, mostly organic, were formulated and tested as 

 herbicides. Few have proven more valuable and economical than 

 copper sulfate for algae, 2,4-D for control of emergent and broad- 

 leafed aquatic plants and sodium arsenite for submersed weeds. 



Dalapon is proving valuable for control of hard-to-kill 

 grasses, cutgrass, manna grass, cattails, etc. 



Silvex appeared for a while to be the answer to the pond 

 operator's dream of a chemical to use for submersed weed control; 

 non-toxic to man, domestic animals, and fish, and safe to handle. 

 It has most of these good points, but is expensive (about $12 per 

 gallon); apparently, it is not as effective on the Potamogetons 

 (largest group of submersed plants) as first thought; it has a 

 higher toxicity to fish than was apparent at first and a phenolic 

 contaminant sometimes causes the off-flavoring of fish in treated 

 ponds. On the definite credit side, however, is its use at low 

 rates of application to kill cowlilies, white water lilies, parrots 

 feather and watershield. 



Diquat , available in limited quantities and expensive (about 

 $7 per pound) , has the attributes of the ideal herbicide for sub- 

 mersed plants, including low rates of application for pondweeds and 

 low toxicity to fish. 



Another promising herbicide for submersed weeds is Hyamine 

 1622, which is much less expensive (costing about $1.35 or less 

 per pound). It has a low toxicity to fish, but like Diquat, remains 

 to be thoroughly field tested. 



Endothal has low toxicity to fish and bottom animals and in 

 limited field tests has proven effective for control of submersed 

 pondweeds at rates varying from 1.0 to 5.0 p. p.m. 



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