1922.] PUBT JC DOCUMENT — No. 31 . Go a 



occurrence of the disease, will not be necessary, thus eliminating 

 the necessity of spraying in years of no mildew. 



The season was further notable for the almost comj)lete 

 absence of potato late blight which so often proves disastrous 

 to the crop in years when wet weather occurs in August and 

 September. The condition is explained by the fact that the 

 rainfall and humidity both of these months and of October 

 were considerably below normal. 



Diagnosis of Plant Diseases. 

 A statement of the kind and character of the plant diseases 

 for which diagnostic service was requested during the year 

 follows: — 



