Oct.8.i92i Temperature and Humidity Studies of Fusaria Rots 77 



(b) Fusarium oxysporum grows more rapidly and produces a more ex- 

 tensive rotting of the tuber than the other two at a temperature of 16° C. 

 and above. 



(c) Fusarium trichothecioides is capable of producing a rot at much 

 lower temperatures than the others, in some cases causing rotting at 

 5°C. 



{d) The relative humidity plays a very important role in determining 

 the progress of tuber rots and has the same influence on all three species. 

 In every experiment it was noticeable that there was a gradual increase 

 in the amount of rot corresponding to an increase in relative humidity. 

 With a high humidity at a given temperature the rotting was always 

 greater than at a temperature 5° to 10° C. higher but with a low humidity. 

 The Fusaria used can all live and sporulate at the low temperature of 9°, 

 and with low relative humidities, but they are not capable of producing 

 a rot under these conditions. 



Inasmuch as the three species of Fusaria used in these experiments 

 represent the common types causing storage-rots of potatoes, it is clear 

 that considerable attention should be given to moisture as well as tem- 

 peratures where incipient rot occurs in stored tubers. It is also en- 

 tirely probable that a rotting of the tubers initiated at high temperatures 

 and high relative humidities could be completely checked by submitting 

 the tubers to lower temperatures and lower humidities. 



LITERATURE CITED 

 (i) AppEt, Otto, and Wollenweber, H. W. 



I910. GRUNDLAGEN EINER MONOGRAPHIE DER GATTUNG FUSARIUM (LINK). 



Arb. K. Biol. Anst. Land. u. Forstw., Bd. 8, Heft i, 207 p., 10 fig., 3 

 pi. (i col.) Verzeichnis der wichtigsten benutzten Schriften, p, 

 196-198. 



(2) Bary, Anton de. 



1861. DIE gegenwartig herrschende kartopfelkrankheit, ihre ursache 

 UND ihre verhutung. eine pflanzenphysiologische unter- 



SUCHUNG . . . 75 p., I pi. I^ipzig. 



(3) BisBY, G. R. 



1919. STUDIES ON FUSARIUM DISEASES OF POTATOES AND TRUCK CROPS IN MIN- 



NESOTA. TECHNICAL. Minn. Agr. Exp. Sta. Bui. 181, 58 p., 30 fig. 

 Bibliography, p. 40-44. 



(4) Carpenter, C. W. 



1915. SOME POTATO TUBER-ROTS CAUSED BY SPECIES OF FUSARIUM. In Joiir. 



Agr. Research, v. 5, no. 5, p. 183-210, pi. A-B (col.), 14-19. Litera- 

 tiire cited, p. 208-209. 



(5) Edson, H. a., and Shapovalov, Michael. 



1920. TEMPERATURE RELATIONS OF CERTAIN POTATO-ROT AND WILT-PRODUCING 



FUNGI. Ir„ Jour. AgT. Research, v. 18, no. 10, p. 511-524, 9 fig. 



(6) Frank, Albert Bernhard. 



1898. UNTERSUCHUNGEN USER DIE VERSCHIEDENEN ERREGER DER KARTOFFEL- 



FAULE. In Ber. Deut. Bot. Gesell., Bd. 16, Heft 8, p. 273-289. 



