190 
Journal of Agricultural Research 
Vol. V, No. s 
was Idaho Rural. However, many of these were almost completely 
destroyed, being very mushy and “leaky.” 1 The organism was 
recovered from all varieties, two reisolations being made from the 
Rurals. 
F. oxysporum 2999; isolated on March 14, 1914, from a tuber with 
wound-invading brownish dry-rot from Brookings, S. Dak. Culture, 
16-day-old pionnotes on stem of Melilotus alba. The results were the 
same as with strain 2997. The organism was recovered in all attempts, 
reisolations being made from all varieties except Early Rose. 
F. oxysporum 3045; a reisolation of strain 2997 from a rotted tuber 
of the Idaho Rural variety 20 days after inoculation at 23.i° C. After 
incubating for 21 days at an average temperature of 25.6° C. all tubers 
of all varieties—i. e., Netted Gem, Idaho Rural, and People's—showed 
a deep, progressive rot, a brown zone about the inoculation prick 
surrounded by a water-soaked area more or less brown in color. The 
organism was recovered by three isolations. 
In a subsequent trial with strain 3045, inoculating the four varieties 
Idaho Rural, Netted Gem, Burbank, and Pearl with a i-month-old 
culture on a stem of Melilotus alba and incubating for 37 days at an 
average temperature of 20.4 0 , similar results were obtained. Seven 
reisolations were identified from this lot. 
F. oxysporum 1948; isolated and identified by Dr. Wollenweber from 
a secondary rot following infection by Phytophthora infestans . Material 
from Honeoye Falls, N. Y., February, 1913. Culture used was 1 month 
old on stem of Melilotus alba . The results at different incubation 
periods and temperatures are as follows: Ten tubers incubated for 24 
days at an average temperature of 24.6° rotted, four slightly decaying 
in all punctures and six wet-rotting. Organism recovered. One tuber 
at 18.4° rotted in 51 days, while one at 17.8° failed to decay in this 
time, but the organism persisted. 
F. oxysporum 2413; isolated and identified by Wollenweber in January, 
1913, from a potato of the Up-to-Date variety, grown on Potomac Flats, 
Washington, D. C., in 1912, affected with the ring disease. Cultures used, 
one on stem of Melilotus alba and one on a potato, cylinder 25 days old. 
Result of incubation at 25.7 0 C. for 14 days: All inoculated tubers de¬ 
cayed, 50 per cent being very badly decomposed with wet-rot; organism 
recovered by four reisolations. Two tubers incubated at 17.8° and 18.4°, 
respectively, for 51 days suffered a rather dry rot; organism recovered. 
F. oxysporum 3395; reisolation of strain 2413 from badly rotted Green 
Mountain potato tuber. Culture used, 4-day-old potato cylinders. 
Owing to the fact that certain of the tubers were rotting badly, the 
experiment was concluded before some of the others had started to decay. 
All of the Pearls, 95 per cent of the Netted Gems, and 50 per cent of the 
1 Orton (9, p. 11) described a soft-rot caused by Rhizopus nigricans. Potatoes affected with this disease 
are called “leaky” or “ melters/’ 
