10 



BULLETIISr 1102, U, S. DEPARTMENT OF AGRICULTURE. 



suit of this series was that 1 produced bacteria, 7 grew fungi, and 40 

 were sterile. 



Curtis nuts sent to the writer from Blackshear, Ga., constituted 

 the last series cultured. Of 88 spots that were plated, eight grew 

 bacterial colonies, 20 grew fungi and 60 spots produced no growth. 



The record of these laboratory cultures is shown in Table 2. 



Table 2. — Record of lahorato7-]j cultures of the kernel spots of three varieties of 

 pecans, in November and December, 1921. 



Date cultiu-ed, 

 1921. 



Culture media. 



Variety and 

 source. 



Num- 

 ber of 

 cul- 

 tures. 



Num- 

 ber 

 with 



bacter- 

 ia. 



Num- 

 ber 

 with 



furjgi. 



Ntirn- 



ber 

 sterile. 



Date of final 

 examination. 



Nov. 30.. 



Beef agar. . . 



Curtis from cages. . 

 do 



17 

 26 

 15 

 65 

 60 

 51 

 25 

 25 



21 



48 

 03 



14 

 18 

 3 

 28 

 6 

 

 2 

 2 







1 

 6 



1 

 6 

 12 

 9 

 3 

 3 

 1 

 3 



9 



7 

 17 



2 

 2 

 



Dec. 6. 



Dec. 1.. 



. .do 



Do. 



Dec 2 



Com-meal agar 



Beef agar 



Corn-meal agar 



.do 



Dpc. 7. 



Do 



Dec. 10 



Curtis not caged... 

 Schlev from cjit^es 



28 ; Do. 

 51 i Dec. 20. 



Dec. 12 . 



.do ' -do 



48 1 Do. 



Dec. 16... 



.do -do. 



22 ' Do. 



Dec. 20 



Dec. 23 



...... do 



. .do 



Curtis, Blackshear, 

 Ga. 



Frotscher, 

 Thomasville, 

 Ga. 



Schlev, Thomas- 

 ville, Ga. 



Curtis, Blackshear, 

 Ga. 



20 i Dec. 20. 

 12 1 Dec. 31. 



Do 



...do 



40 1 Do. 



Do 



do 



40 : Do. 









Total 



1 



410 



80 71 1 265 





1 











Table 2 indicates that of the 416 kernel spots cultured, 63.7 per 

 cent produced neither fungus nor bacterial growth. The spots most 

 generally producing growths in cultures were those taken from nuts 

 badly injured by many insect punctures. Cultures made from spots 

 that were only slightly or not at all discolored internally generally 

 proved to be sterile. 



Since no constant form appeared in the cases where organisms did 

 develop, it was thought highly improbable that kernel-spot could be 

 attributed to any of them, especiallj'^ since most of the cultures re- 

 mained sterile. Nevertheless, for the sake of completeness, from 25 

 to 50 inoculations were made in healthy pecan kernels, employing 

 each of the different forms isolated. 



After an interval of seven days, at a temperature of about 22° C, 

 the kernels were all found to be softening more or less around the 

 points of inoculation. None of the inoculations produced the mealy, 

 dry spots which characterize pecan kernel-spot. 



Since no form of Coniothyrium was developed from the cultures, 

 an attempt was made to develop it from badly affected kernels by 

 placing them for several days in a moist chamber. Only negative 

 results were produced. 



