66 Report of State Board of Horticulture. 



or other plant parts are covered with a fungicide before or imme- 

 diately after the spores are blown onto them, the spores will be de- 

 stroyed, 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 develop into fungous 

 growths, causing the parts attacked to be diseased. Or the fungi- 

 cide originally sprayed onto the plant may be washed off by rains, 

 thus leaving the plant unprotected against the spores that are con- 

 stantly 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 num- 

 ber of sprayings must depend to a large extent upon weather con- 

 ditions. Warm, damp weather, or a dry, hot season, followed by 

 rain, are favorable conditions for the development of fungi, hence, 

 if these conditions prevail, it is important that the spraying should 

 be fi-equent enough to keep well protected the parts liable to at- 

 tack. Sometimes it is necessarj^ to spray every day or every two 

 or three daj^s, while at other times 10 days may elapse between 

 sprayings. Spraying, like cultivation, pruning, and other field 

 operations, is largely a matter of judgment, and the more thor- 

 oughly the subject is understood the more effective the work will be. 



WHY IS IT NECESSARY TO SPRAY EVERY YEAR? 



It is impossible to exterminate fungi. We may hold them in 

 check, or we may even prevent entirely their growth upon certain 

 plants ; but they are often so small, their habits of life so variable, 

 and tlieir spores so resistant that extermination is out of the ques- 

 tion. It is impossible to know at the beginning of the season 

 whether the conditions will be favorable or unfavorable for the de- 

 velopment of fungi, hence, in order to be on the safe side, it is 

 necessary to begin each season with spraying. It is essential, there- 

 fore, that spraying should be as regularly a part of the fieldwork 

 for successful crop raising as plowing, fertilizing, and the other 

 operations necessary for crop production. Furthermore, the ef- 



