254 HORTICULTURE FOR SCHOOLS 



seed potatoes, and the precaution should be taken of treating 

 all seed. 



The method is as follows : Dissolve a fluid ounce of forma- 

 lin in two gallons of water, and soak potatoes in the solution 

 for at least an hour. The seed may then be used at once, 

 or dried off and used as desired. If a large amount of seed 

 is to be treated, the solution should be prepared by the barrel, 

 but the proportions given above are maintained. 



365. Brown-rot is a very common disease in all parts of 

 the United States. It attacks the peach especially and other 

 stone-fruits as well. Its development is favored by warmth 

 and especially by a moist condition of the atmosphere. The 

 losses which can be traced to it are always considerable and 

 sometimes very heavy. 



The disease is produced by a species of fungus which gains 

 access to the fruit and grows there, destroying the tissue. 

 After the fungus has progressed sufficiently, the fruit turns 

 dark in color and begins to shrivel. This is the first indication 

 of the progress of the disease. From the fruit, the fungus 

 may enter the limbs, but, as a rule, the woody parts of the 

 plant are not very susceptible. 



Frequently fruit which has become infected with the dis- 

 ease is allowed to hang on the trees and forms a prolific source 

 of trouble during the following year. Spores are present in 

 great numbers in these dried-up fruits and are easily carried 

 to the new ones. Access is facilitated if the fruit is bruised, 

 but the disease also gains entrance even where the skin is 

 whole and healthy. The first precaution in the treatment of 

 the disease is, therefore, to see that all of the affected fruit 

 of the previous year is taken off the trees and either carried 

 off and burned or plowed under deeply enough so that the 

 spores do not come to the surface of the ground. 



The next step in control is the use of bordeaux mixture 

 during the late dormant season of a strength of approximately 

 6-6-50. It is impossible, however, to reach all of the spores 



