88 Report of State Board of Horticulture. 



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 development 

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

 that the spraying should be frequent enough to keep well 

 protected the parts liable to attack. Sometimes it is necessary 

 to spray every day or every two or three days, while at other 

 times ten days may elapse between sprayings. Spraying, 

 like cultivation, pruning, and other field operations, is largely 

 a matter of judgment, and the more thoroughly 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 their spores so resistant that extermina- 

 tion is out of the question. It is impossible to know at the 

 beginning of the season whether the conditions will be favor- 

 able or unfavorable for the development of fungi, hence, in 

 order to be on the safe side, it is necessary to begin each sea- 

 son with spraying. It is essential, therefore, that spraying 

 should be as regularly a part of the fieldwork for successful 

 crop raising as plowing, fertilizing, and the other ojDerations 

 necessar}^ for crop production. Furthermore, the effects of 

 spraying are cumulative, tliat is, the effects of spraying and 

 keeping fruit trees free from disease this year will give a bet- 

 ter crop next year. Even with trucking crops that die down 

 in the fall the danger from disease next year in a particular 

 field will be greatly reduced if the field is kept free from dis- 

 eases this season. 



DOES SPRAYING SOMETIMES INJURE FOLIAGE AND FRUIT? 



If fungicides are not properly made they will burn the 

 foliage and discolor the fruit. It is a well-known fact that 

 the foliage on some plants is much more tender than it is on 



