SCAB 275 



it is within the tissues. In a short time, the fungus bears 

 fruit by sending up above the surface many small stalks 

 which bear thousands of other microscopic spores, which 

 are afterwards carried to other portions of the plant and 

 to other plants. This is a typical example of the life his- 

 tory of a fungus. It shows pretty clearly that common 

 fungous diseases must be controlled by spraying before 

 the spores germinate. Spraying 

 is a preventive measure rather 

 than a cure. We cannot cure 

 potatoes after they have been 

 blighted or apples after they 

 have been affected with scab, 

 but we can prevent the spores 

 from spreading to others. Bor- 

 deaux mixture and lime-sulphur 

 solution are the two most 

 effective sprays for controlling 

 fungous diseases. 



Scab. This is one of the 

 most common fungous diseases 



Of apples and pears, especially Fig. 148. Pear scab on leaf and 



in wet seasons. It is most 



apparent upon the fruit, causing brown or black blotches 

 with whitish edges. When the disease becomes excessive, 

 it cracks the fruit and causes it to be misshapen. It also 

 occurs as brown spots on the leaves and causes them to 

 turn yellow and fall. Sometimes this disease attacks 

 the young blossom stems and girdles them, causing the 

 young fruits to fall. Some varieties, like the Snow apple 

 and Flemish Beauty pear, are more susceptible than 

 others. 



