Nov. is, 1920 Vascular Discoloration of Irish Potato Tubers 



293 



Table VIII. — Summary of disease and recovery in percentage 



OBSCURE DISEASE GROUP 



HEALTHY GROUP 



PARASITIC DISEASE GROUP 



Grand total . 



Healthy Pearl.. 

 Diseased Pearl . 



Total. 



Healthy Rural New Vorker. 

 Diseased Rural New Yorker. 



Total. 



4-35 

 o. 00 

 19.89 

 41. 18 

 67.86 

 66.67 

 37-38 

 41-33 



Total 28. 21 



38.59 



21.65 



45- 73 



25-05 

 39.01 



8. 70 



20. OO 



34-68 

 54.41 

 60. 71 

 26. 67 

 34-58 

 60. 00 



39-39 



27.30 

 55-48 



48.82 

 45-05 



13-54 

 38.24 

 36.67 

 61.98 

 65.08 

 76.47 

 48.08 

 3I-H 



44. 76 



53-38 



12. 36 

 63.04 



29. 06 



31-65 



13.98 

 46.67 

 25.00 

 62. 76 

 50.00 

 26. 67 

 33-78 

 66.67 



43-27 



60.65 



19. 01 

 58.94 



36.60 



45-94 

 45-13 



II. 76 

 33-33 

 20. 74 

 5C97 

 65- 93 

 71.88 

 40.88 

 37-SO 



33- 57 



20. 18 

 54-89 



26.68 

 39-43 



12-93 

 42.86 

 34-17 

 58.72 

 53-33 

 26. 67 

 34- 25 

 62. 28 



40. 70 



25-97 

 57-41 



31- 76 



47-65 



45.08 



46-95 



85-71 

 7.69 

 57-26 

 3-82 

 I.67 

 30.43 

 60. 00 

 26. 67 



31. 16 



20. 24 

 3- 14 



62.38 

 46.36 



56.87 



60. 00 

 26. 67 

 71.71 

 74-55 

 33-33 

 62. 50 

 64. 52 

 70.42 



66.89 



47-31 

 65.26 



74.40 

 67. 67 



72.64 



SUMMARY 



In the material studied, vascular discoloration of stem-end tissues of 

 Irish potato tubers was not found to be proof of the presence of para- 

 sitic fungi. Discolored bundles were often sterile, and fungi were fre- 

 quently isolated from tissues which appeared normal. 



The organisms recovered, in the order of their greatest frequency, 

 were Fusarium 720, Alternaria 615, bacteria 241, Verticillium 147, 

 Penicillium 104, Colletotrichum 91, Rhizoctonia 12, miscellaneous 87. 



