UNITED STATES DEPARTMENT OF AGRICULTURE 



IBi BULLETIN No. 1102 



1^ 



Washington, D. C. PROFESSIONAL PAPER September 26, 1922 



KERNEL-SPOT OF THE PECAN AND ITS CAUSE. 



By J. B. Demaeee, Assistant Pathologist. Office of Fruit-Disease Investigations, 

 Bureau of Plant Industry. 



Page. 



Distribution and history 1 



Economic importance 2 



Description of kernel-spot 3 



Present investigations 4 



Supplementary experiment 8 



CONTENTS. 



Page. 



Laboratoi-y cultures of kernel-spot 8 



Analysis of results 11 



Control measures 11 



Summary 14 



Literature cited 15 



DISTRIBUTION AND HISTORY. 



The pecan kernel-spot is found throughout the southern pecan belt, 

 including North Carolina, South Carolina, Georgia, Florida, Ala- 

 bama, Mississippi, Louisiana, and Texas. This trouble is not evenly 

 distributed over these States, but is more prevalent in restricted 

 localities. Its appearance is more or less sporadic ; that is, it may be 

 abundant one season and almost absent the season following. 



The first published record of an investigation of pecan kernel-spot 

 was in 1914 by Eand (5) .^ As set forth in this preliminary account, 

 the fungus C oniothyriuin caryogenuni Rand was isolated from affected 

 pecan kernels. Rand reported that by subsequent inoculation in 

 healthy kernels with this fungus he was able to produce in a series of 

 laboratory experiments during 1912 and 1913 typical pecan kernel- 

 spot symptoms. Laboratory inoculations with this fungus were so 

 largely positive that it was considered by him to be the cause of the 

 disease. 



Since Rand made no observations or investigations in the field in 

 reference to pecan kernel-spot, he was unable to determine the time 

 and manner in which the infection of his isolated fungus took j)lace 



^ Serial numbers (italic) in parentheses refer to " Literature cited " at the end of 

 this bulletin. 



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