WEED CONTROL 



For 1 acre-foot (an acre of water 

 1 foot deep) use 5.3 gallons of 

 sodium arsenite spray ; for i/^ acre- 

 foot, or for 4 p. p. m. on 1 acre-foot, 

 use 2.65 gallons. 



If you are in doubt concerning 

 the type of vegetation in your pond, 

 you should send samples of the 

 questionable species with either the 

 blossoms or fruit to the nearest 

 State University for identification. 

 Submerged vegetation should be 

 thoroughly dried before mailing it. 

 Preparation of the specimen is best 

 accomplished by spreading the 

 plant flat on a piece of paper or be- 

 tween the folds of a newspaper, and 

 placing a weight on it until dried. 

 Attach a label to each sample giv- 

 ing such information as you can 

 about the location and depth of 

 water where the plant was found. 



APPLYING CHEMICAL AGENTS 



The best way to apply a weed 

 killer is in liquid form. It is neces- 

 sary that sprays be applied directly 

 on the plants (in controlling emer- 

 gent vegetation), or to areas where 

 the plants cover the bottom of the 

 pond (in submerged vegetation). 



Sodium arsenite 



Sodium arsenite is heavy and 

 sinks rapidly to the bottom. Con- 

 sequently, the areas to be treated 

 can be restricted by spraying only 

 those places where it is intended to 

 kill submerged vegetation. Some 

 time will elapse before the effect of 

 the chemical can be noticed. Since 

 the vegetation that is killed will be- 



gin to decay and remove oxygen 

 from the water, it is advisable to 

 treat not more than one-third of 

 the pond at one time. The re- 

 mainder can be sprayed a few days 

 later. This gives the fish an op- 

 portunity to move into waters 

 where oxygen is available. 



To hasten the effect of sodium 

 arsenite, it is helpful to fertilize the 

 areas where the weeds are begin- 

 ning to die. This will produce a 

 waterbloom and oftentimes will re- 

 sult in a complete kill of all vege- 

 tation in the pond, thus eliminat- 

 ing the need for the use of chemi- 

 cals on the untreated areas. 



Sodium arsenite is very poison- 

 ous, and care should be taken when 

 applying it that the spray is not 

 inhaled and does not come in con- 

 tact with the skin. Livestock 

 should be kept away from sprayed 

 ponds for at least 2 days. Con- 

 tainers in which the chemical has 

 been mixed should be thoroughly 

 cleaned and removed from places 

 where livestock may have access to 

 them. The water itself is not poi- 

 sonous, since the amount of chemi- 

 cal used is not sufficient to provide 

 a lethal dosage. 



Copper sulfate 



Copper sulfate should be ob- 

 tained in small crystals so that it 

 can be spread evenly over the area 

 to be treated. As in the case of 

 sodium arsenite, only part of the 

 pond should be treated at one time, 

 and copper-sulfate crystals should 

 never be in excess of 0.5 p. p. m. for 

 the pond as a whole. Also, fertili- 



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