9^4 Rural School Leaflet 



We have learned that infection takes place during rainy or foggy 

 weather because it is during such weather that the spores are produced, 

 are scattered, and germinate. Therefore it is important to make the 

 application before the rainy period comes. Such periods are forecasted 

 by the Weather Bureau, and by studying the daily weather map one may 

 soon learn to forecast storms. 



In general, it may be said that five to seven applications should be made, 

 depending on weather conditions, making the first when the plants are 

 six to eight inches high. When potato beetles are troublesome, paris 

 green should be added at the rate of i pound to 50 gallons of the mixture. 

 Other poisons, such as arsenate of lead, arsenite of soda, or arsenite of 

 lime, may be used in place of paris green if desired. Experience with 

 lime-sulfur in place of bordeaux mixture has not been entirely satisfactory. 

 In order to do thorough work, high pressure and nozzles producing a fine 

 mist or fog of the mixture are necessary. 



Preparation of bordeaux mixture. — Bordeaux mixture is made by mixing 

 a dilute solution of copper sulfate (blue vitriol) with a dilute solution of 

 lime. The mixture may be made of different strengths by using different 

 amounts of the copper sulfate and lime to a given amount of water. A 

 mixture made by using three pounds of copper sulfate and three pounds 

 of lime to fifty gallons of water is probably strong enough to control this 

 fungus; but because of the stimulating action of bordeaux mixture on the 

 potato plant, a strength of five pounds each of copper sulfate and of lime 

 to fifty gallons of water is usually recommended, and this is indicated by 

 the formula 5-5-50. To make bordeaux mixture of any strength, proceed 

 as follows: 



Make a stock solution of copper sulfate by dissolving 45 pounds 

 of copper sulfate in 45 gallons of water. A gallon of the solution will 

 then contain one pound of copper sulfate. If the crystals placed in a 

 gunny sack are suspended so as to be just immersed, they will dissolve 

 in the coiu^se of three or four hours. 



Make a stock solution of lime by placing about a bushel of good 

 stone lime in another barrel and slake by adding water slowly, being 

 careful not to " drown " the lime. When all has become pulverized by 

 the slaking, add water to make a paste, after which enough more may 

 be added to make 45 gallons. This should not be allowed to dry out. 

 Hydratcd lime that does not require slaking may be used in place of 

 stone lime, but air-slaked lime should never be used. 



Fill the sprayer about three fourths full of water. If a 5-5-50 solution 

 is desired, 5 gallons of copper sulfate stock solution should be added to 

 this water for every 50 gallons of mixture to be made. Stir until the solu- 

 tion is well diluted, and add 5 gallons of the stock solution of milk of hme. 



