72 



Journal of Agricultural Research 



Vol. XXII, No. 2 



The results were taken after seven weeks, and the penetration of the 

 tubers was measured in millimeters, as shown in Table 11. The number 

 of individuals was so small that slight discrepancies in the tabulated 

 results are found. Fusarium trichothecioides produced a slight rot at 

 lower temperatures than F. oxysporum but did not produce as extensive 

 a rot at the higher temperatures. At 5° C. the only rotting found was 

 with one strain of F. trichothecioides, at 100 per cent humidity. No 

 rotting was found at the temperature of 9° at the lower humidities, but 

 there was slight rotting at this temperature at the higher humidities, 

 especially with F. trichothecioides. It is noticeable that at 9° with the 

 relative humidities of 66 and 100 per cent, the amount of rotting is greater 

 than at the increased temperature of 16°, with the relative humidities of 

 I and 33 per cent. The same comparative results are found between 

 the amount of rotting taking place under the several humidities at a 

 temperature of 16° and of 25°. The results do not conform with the 

 report of Jamieson and Wollenweber {8), that penetration of the tuber 

 by F. trichothecioides is favored by low humidities. The work by Link (9) 

 and Wilcox, Link, and Poole {26), however, would indicate that more 

 rapid rotting takes place in an atmosphere of high humidity, thus agreeing 

 with the results shown in this experiment. The results of F. oxysporum 

 accord well with those obtained in experiment 3. 



Table II. — Extent of penetration of tubers in experiment 4 



Experiment 4 A, May 16, 191 7. — In order to check up the possible 

 error due to differences in the age of the tubers used in the various tests, 

 the following experiment was started. New tubers of the Bliss Triumph 

 variety were used in comparison with tubers of the same variety that had 



