152 REPORT OP STATE BOARD OF HORTICULTURE. 



into a leaf or into a fruit, and thus produces the destruction 

 of the former or the decay of the latter, first lodges on the 

 leaf or on the fruit as a tiny spore. If that spore can be 

 destroyed without injury to the leaf or the fruit, disease may 

 be prevented, and therefore the necessity of spraying. 



WHY SHOULD WE SPRAY EARLY? 



As already stated fungus spores are sometimes formed in 

 the fall and remain in open fields all winter uninjured. 

 These spores often lodge in the crevices of the bark of trees, 

 or in other convenient places on the trunk and branches of 

 trees. When the leaves and fruits appear the spores are 

 blown onto these newly formed parts and cause them to be 

 diseased. The object in early spraying, even while the trees 

 are still dormant, is to kill the spores that are lodging on the 

 tree and waiting for favorable conditions for development. 

 Again, every spore must remain for a longer or shorter time 

 in a dormant state, even after it reaches the proper place for 

 its development, just as seeds remain for a little time under 

 proper conditions for germination before they begin their 

 growth. If the leaves or other plant parts are covered with 

 a fungicide before or immediately after the spores are blown 

 onto them, the spores will be destroyed, and the plant will 

 remain free from disease. 



WHY IS IT NECESSARY TO SPRAY MORE THAN ONCE? 



After a plant has been sprayed new leaves or fruits are 

 often formed, which are not covered with the fungicide. 

 Spores may be lodged on these newly formed parts and de- 

 velop into fungous growths, causing the parts attacked to be 

 diseased. Or the fungicide originally sprayed onto the plant 

 may be washed off by rains, thus leaving the plant unpro- 

 tected against the spores that are constantly carried about in 

 the air. 



HOW OFTEN IS IT NECESSARY TO SPRAY? 



No definite rule can be given in regard to the number of 

 times any set of plants should be sprayed in a single season. 

 The number of sprayings must depend to a large extent upon 

 weather conditions. Warm, damp weather or a dry, hot 

 season followed by rain, are favorable conditions for the de- 

 velopment of fungi, hence, if these conditions prevail, it is 



