ASCOMYCETES 



177 



this point. Ninety-two per cent believed that a cold spring is 

 favorable to the disease ; more than seventy-five believed the wet 

 weather also to be a factor. Six and seventeen per cent, respec- 

 tively, expressed opinions opposing the view that cold and mois- 

 ture are influencing factors. The memorable leaf -curl years in 

 New York and Ohio, 1893, 1897, and 1898, were preceded by 



Fig. 64. Peach Leaf Curl 



cold and humid conditions during April, the time when the buds 

 normally start. On the other hand, there is no record that the 

 peach leaf curl has ever been particularly destructive during a 

 warm and relatively dry spring. So firm is the opinion of a few 

 of the practical growers as to this climatic relationship that they 

 refuse to believe anything more than that the weather is the direct 

 cause of the leaf curl. Moreover, heavy dews appear to be of in- 

 significant environmental importance, and in view of the conditions 

 developing dew, this would be anticipated. 



