516 Rp^roRT OF THE Mycologist of the 



When it was discovered that the " pimples " on potato tubers 

 were caused by the attacks of flea-beetle grubs it naturally oc- 

 curred to us as being strange that the " pimply " potato' trouble 

 should be confined to eastern Long Island. The flea-beetle is dis- 

 tributed over a large portion of the United States, and it is not 

 easy to believe that only eastern Long Island flea-beetle grubs 

 should feed upon potato tubers. Nevertheless, this habit of the 

 insect does not appear to have been observed elsewhere. 



The grubs were first observed feeding upon the potato tubers 

 July 7, but the large number of pupae found in the soil showed 

 that they had commenced to feed somewhat earlier than this 

 date — how much earlier it is impossible to state. The grubs were 

 found in abundance in various places on Long Island until 

 August, and Mr. Sirrine found some as late as August 15. 

 Tubers showing the " slivers " have been received from Orange 

 county also.* 



Knowing that the grubs had everywhere been abundant on 

 Long Island we expected to find the crop of 1896 very " pimply." 

 Such, however, was not the case. The trouble was not at all 

 common. As a possible explanation of this failure of the in- 

 jured tuber to produce " pimples," the first idea to suggest it- 

 self was that certain varieties respond more readily than do 

 others to injuries of the skin. This theory was soon exploded 

 by the discovery that both " slivers " with " pimples " and 

 " slivers '' without " pimples " may be found on the same tuber. 

 In order that the grub-punctine may be followed by the pro- 

 duction of a " pimple " it is probably necessary that the tuber 

 be at a certain stage of growth. Thus the formation of 

 '^ pimples" is the exception instead of the rule, and unless 

 " pimples " are formed the affection is not conspicious, which 

 probably accounts for its not having been previously discovered. 



A knowledge of the cause enables us to prescribe a remedy. 

 It seems probable that the grubs can best be controlled by pro- 



. Since writing the above. Mr. C. W. Mally, at our request has ^*"'lly ^^%']]i".*:^,iP^*?trtn 

 Prown on the Ohio Experiment Station farm at Wooster Ohio, f « 4°".?'lo*,^|„<?; ^ lowk 



tk)n of potatoes in the St. Louis markets, failed to And eitlier - pimples or shve. s. 



