Plant Sanitation. 



394 



Dissolve the four pounds of copper sulphate in four gallons of water and slake 

 four pounds of lime in four gallons of water. When cool pour the two solutions to- 

 gether simultaneously into a tub. Allow the resulting precipitate to settle, decant off 

 the liquid, pour the wet mass of material into a double flour bag, and squeeze out as 

 much water as possible. Then spread out the dough-like mass in the sun to dry. 

 After a day's drying it can easily be crumbled into an impalpable powder by crushing 

 with a block of wood or even with the hand. This powder should be screened 

 through a sieve of brass wire having at least 80 meshes to the inch and should then 

 be thoroughly mixed with 60 pounds of slaked lime dust. 



The lime dust is best prepared by slowly sprinkling a small quantity of water 

 over a heap of quicklime, using barely enough water to cause the lime to crumble 

 into a dust. The heat generated will soon drive off the excess of moisture, and the 

 dust should then be passed through a screen of 80 meshes to the inch. This powder 

 is usually applied by means of a blower. 



If desired, four pounds of sulphur and one pound of Paris green may be added 

 to each 60 pounds of Bordeaux mixture dust. 



Finely powdered copper sulphate, used with lime as a conveyer, is also some 

 times applied to plants. When so employed at least 15 pounds of slaked lime dust 

 should be used to each pound of copper sulphate, as this will make a pretty strong 

 fungicide. 



The manufacturers of dust sprayers have on the market several ready-made 

 preparations. As a rule, these do not contain as much copper sulphate as is recom- 

 mended in the above formula. 



Value of Dust Sprays.— The expense of handling large quantities of water in 

 making up the liquid Bordeaux mixture has deterred many orchardists from using 

 it. In case of certain mountain orchards, it is not practicable to haul the water up 

 the steep hills or mountain sides, nor is it feasible to drive between the tree rows 

 with heavy spraying tanks. There is a very urgent demand, therefore, for success- 

 ful dry fungicides to be applied without the use of water, as the weight of the mate- 

 rial handled is very much reduced. So far, however, in the treatment of apple scab, 

 bitter-rot of the apple, pear leaf-blight, black-rot of the grape, and other fungous 

 diseases requiring careful spraying, the dust method may be regarded as still in the 

 experimental stage and of doubtful value. It is not to be compared with properly 

 made Bordeaux mixture applied as a spray in the treatment of these diseases. In 

 the treatment of the codling moth, however, better success has been obtained, and 

 some help may be expected against fungi. Mr. Scott's formula is the result of consid- 

 erable experimenting, and it is recommended as the best one to use. The writer is 

 not able, however, to recommend dust spraying for general use, and wherever liquid 

 spraying is practicable it should by all means be used. 



FORMULAS FOR OTHER COPPER SOLUTIONS. 



Copper Sulphate Solution.— The formula for copper sulphate solution is 

 as follows : 



Copper sulphate (bluestone) ... ... ... pounds 3 



Water ... ... ... ... ••• gallons 50 



Dissolve the bluestone in the water in the same manner as for the prepar- 

 ation of Bordeaux mixture. A more dilute solution (2 pounds to 50 gallons) 

 is sometimes used on foliage. 



Caution. — This solution is severely injurious to plants in foliage, and should 

 therefore be applied only during the dormant period. Even the more dilute solution 

 is usually injurious to leaves and flowers. 



