MICHIGAN ACADEMY OF SCIENCE. 

 SUMMARY TABLE No. Ill 



283 



FUSARIUM WILT (FUSARIUM OXYSPORUM). 



This disease cut down tlie yield throughout the state to some extent by 

 the formation of small unmarketable potatoes in the affected hills. The dis- 

 tribution of infection through the state was not observed to be correlated wtih 

 moisture conditions. In only a few cases were the farmers practicing the 

 method of cutting off the stem end of the seed piece to determine the presenc-e 

 or absence of the disease. Seventy per cent of the counties visited showed the 

 disease, 21% of the observed fields being infected. The following table, sum- 

 marizing my observations, shows that of the 71 infected fields observed only 

 6% had the disease present in amounts over 1% : 



SUMMARY TABLE No. IV 



EARLY BLIGHT (ALTERNARIA SOLANI). 



Twenty-three per cent of the counties visited showed the disiease present, 

 it being more abundant in the upper peninsula than elsewhere. It is probable 

 that the greater amount of disease in the regions mentioned was due to the 

 greater abundance of moisture present, thus facilitating the spread of the 

 pathogene. In most of the fields the disease was more or less local. Its pres- 

 ence did not seem to interfere with the normal development of the plant to 

 any marked extent, except in a few cases. In the summary table given below 

 the percentage of injury indicates the amount of leaf surface killed. Since 

 the 41 diseased fields showed only 7% of the fields with over 1% injury, the 

 decrease in yield was not marked : 



SUMMARY TABLE No. V 



