LATE POTATO BLIGHT IX IOWA 



the total ss for the three months being 52 per cent. July 



and August of 19 als -s amounting 



to 23 per cent. 



July of 1915 was very wet. in fact with one exception the 

 ttest July in the climatological history of the state. A s 



of 1915 was dry but the total excess of rainfall for the three 



months was approximately 26 per cent. 



3 nee there is a vital relationship between weather conditions 

 covering the period of incubation and since that period also 

 bears a direct relationship to the time of final outbre;. 

 ondary period of infection, we have presented the rainfall 

 data in the following table in ten-day periods which we shall 

 call decades. 



Raixfall fob Svmmee Moxths or 1903 by Decades ex Ixch - 



(Des Moines Station.) 



In two instances, the first decade of June was wet and in one 



The second decade of June in two of the years was dry 



and wet in one. The third decade of all three Junes was dry. 



These conditions point to the fact that an — st ire in 



June is not a requisite fa r the development of this 



- and that even a normal June moisture supply g 



In brief, the moisture supply for June would not s 

 to be a limit:: _ tor for the development of late blight under 

 Iowa conditions. 



July for all three decades of the three years - with one 

 exception wet. The third decade of July was in all instances 



