66 Journal of Agricultural Research voi. xxii. No. 2 



causing a rot of the tuber. Carpenter (4) in 19 15 was the first to report 

 successful infections by inoculations with pure cultures of F. oxysporum. 

 He made these by dipping wounded tubers in a water suspension of 

 spores, wrapping in oiled paper and keeping them at controlled tem- 

 peratures ranging between 17° and 30° C. No detailed experiments 

 were reported except in this saturated atmosphere. He noted, however, 

 that either a dryrot or a wetrot was produced, according to the tem- 

 perature and humidity used. He concluded that a constant storage 

 temperature below 50° F. (10° C.) would prevent the action of F. radici- 

 cola Wollenw., F. eumartii Carp., and F. oxysporum. Previous to this 

 work of Carpenter's, Smith and Swingle {22), in 1910, described a bundle 

 blackening and a dry endrot of the tuber as two stages of the same 

 disease. They attributed this to a Fusarium for which they accepted the 

 name F. oxysporum as first applied to it by Schlechtendahl (2/, p. 139). 

 They noted that the disease continued in stored potatoes and that when 

 potatoes were stored in warm rooms, either moist or dry, they became 

 badly diseased, whereas those stored in cool places kept much better. 

 They did not differentiate this species of Fusarium from others occurring 

 on the potato, and no inoculation experiments were recorded. Manns 

 in 191 1 (//), working with the same disease, stated that the "dormant 

 internal infection" under improper storage conditions becomes so active 

 as to cause a high percentage of dryrot. He noted that the disease was 

 favored by high temperature and considerable moisture. At 36° to 40° 

 F. (2° to 3° C.) the disease made no progress, at 45° to 55° F. (7° to 12° 

 C.) it developed gradually and caused considerable rot, especially when 

 accompanied by high humidity. He made no mention of pure culture 

 inoculations on tubers or morphological studies. 



Jamieson and Wollenweber in 191 2 {8) described a dryrot of the 

 potato tuber caused by a species of Fusarium which they named Fusa- 

 rium trichothecioides Wollenw. They made inoculation experiments and 

 found the most rapid penetration of the tuber to take place at 10° to 12° C 

 in an atmosphere of low humidity. Rotting took place at the high 

 humidities but not as rapidly. Wilcox, Link, and Poole {26) pubUshed 

 on a dryrot of the potato tuber caused by a Fusarium which they called 

 F. tuberivorum W. and L. but which was undoubtedly the F. trichothe- 

 cioides previously described by Jamieson and Wollenweber (<?), They 

 found that a temperature of 8° to 10° C. was only slightly inhibitive to the 

 growth of the fungus and that when potatoes infected with the organism 

 were stored at this temperature, the most rapid decay took place when 

 the humidity was high. Pratt (ly), working with the same disease, 

 found that temperatures ranging from 12° to 25° C. were favorable for 

 the progress of the disease and that dryrot did not develop at temperatures 

 below 2° C. He concluded from storage experiments that in a dry, 

 well-ventilated storage house losses would be very slight at temperatures 

 from 2° to 4° C. 



