88 DDT— Killer of Killers 



disperse it in water, why not forget about the solvent and just 

 disperse the DDT directly in water? This would have lots 

 of advantages — if it could be done. But it can't! The ^ 



crystals of DDT are somewhat waxy; they stick together and | 



form lumps. You can't grind the DDT to a fine powder, 

 and even if you could it would not stay that way. But you 

 can grind DDT with an inert flaky material such as talc, 

 pyrophyllite, or clay and get a very uniform product con- 

 taining up to 50% DDT. And while you are grinding the 

 DDT and the inert material together, add small quantities of 

 wetting agents and sticking agents. Then when you mix 

 the powder with water, it will disperse readily, and when you 

 spray it on your cows or rose bushes the powder that is left 

 after the evaporation of the water will stay put and not blow 

 away with the gentlest zephyr. 



One pound of a 50% wettable powder to about 5 gal- 

 lons of water makes a good residual spray for the control of 

 flies in barns and on cattle, and about 30 pounds per 1,000 

 gallons of water is fine for dipping sheep and hogs for the 

 control of ticks and lice. One disadvantage of the use of 

 wettable-powder sprays is that they leave a white deposit on 

 the walls, and this limits the use of such a spray to barns and 

 similar buildings. 



For agricultural purposes, the powders are mixed with 

 water, usually in the ratio of about 1 to 2 pounds of 50% 

 DDT powder per 100 gallons of water. Sulfur, Bordeaux 

 mixture, organic fungicides, and other materials may be in- 

 corporated in the spray to make an all-round inseaicide and 

 fungicide. 



Dust the Plants 



Some farmers, as well as amateur gardeners, prefer to 



