312 GARDEN GUIDE 



resistant to certain diseases. In some few instances the application 

 of this principle is practical and not a few resistant varieties have been 

 developed in recent years, as, for example. Cabbage immune to yellows 

 and Beans immune to anthracnose. 



Materials Used to Control Plant Diseases 



Among the fungicides used to protect plants from diseases, by 

 spraying or dusting them upon the foliage or fruit, the most commonly 

 employed are Bordeaux mixture, lime-sulfur solution and sulfur in a 

 finely ground form. For disinfecting seeds and tubers to which the 

 spores of pathogenes become attached, the materials most used are 

 formaldehyde and corrosive sublimate. To kill pathogenes which have 

 gained lodging within the seed, hot water at different temperatures has 

 proven most effective. 



Where insects are to be controlled as well as fungi, certain insecti- 

 cides are often combined with the fungicides. Lead arsenate may be 

 added to Bordeaux mixture or hme-sulfur for chewing insects, and 

 Black Leaf 40, a tobacco extract may be similariy used against sucking 

 insects Uke plant hce. 



Corrosive sublimate, a white powder, may be purchased at the 

 drug store. Dissolve 4 ounces in a small amount of hot water and 

 add cold water. May also be obtained in the form of tablets, one of 

 which dissolved in a pint of water gives the desired strength, a 1 to 

 1000 solution. 



Formaldehyde in the form of a 40 per cent solution called formalin 

 may be purchased at the drug store and diluted to different strengths 

 for different diseases. 



Lime-sulfur may conveniently be purchased as the commercial 

 concentrated solution (which should test about 32 Baume) and diluted 

 as indicated below for the various diseases. 



Self-boiled lime-sulfur is prepared by adding a small amount of 

 water to 8 pounds of good stone lime (quick hme) in order to start it 

 slaking. Then 8 pounds of sifted sulfur is added gradually together 

 with small amounts of water to prevent burning. When the slaking 

 is over, make up to 50 gallons with water. This is used chiefly on 

 peaches, but is being largely replaced by sulfur dust apphed dry. 



Bordeaux mixture is made by adding a weak solution of blue 

 vitriol (copper sulfate) to a weak solution of milk of lime. Five 

 pounds of blue vitriol crystals are put into a burlap bag and lowered 

 into 25 gallons of water just below the surface until all of the blue 

 vitriol is dissolved. While this is dissolving 5 pounds of good stone 

 lime are slaked with a small amount of water and then diluted to 25 

 gallons. Good hydra ted lime may be used in place of stone lime. 



