828 Journal of Agricultural Research voi.xxi,No. n 
former “browned” tuber could not be distinguished in any way from 
that usually present in tubers affected by Verticillium albo-atrum or 
F. oxysporum. F. discolor was isolated once from a tuber that was 
“blackened,” eight times from “browned” tubers, and twice from 
“yellowed” tubers; F. discolor var. sulphureum once from a “browned” 
and once from a “yellowed” tuber; F. culmorum, twice from “browned” 
tubers, and F. solani once from a “browned” and twice from “not dis¬ 
colored” tubers. A rather large number, ix per cent of these “other 
Fusarium species” caused no discoloration in the affected tubers, though 
the largest portion of them, 54.3 per cent, were present in “browned” 
tubers. 
Under “miscellaneous fungi” are grouped all other organisms secured 
in the culture series. These are, so far as known, nonparasitic, with a 
few exceptions. Colletotrichum solanicolum O’Gara was isolated from 1 
“blackened,” 12 “browned,” 2 “yellowed,” and 2 “not discolored” tubers. 
Rhizoctonia ( Corticium vagum B. and C.) was isolated from 6 tubers 
having stem-end rot, 3 of which were dry and 3 moist and rather soft, and 
from 8 browned and 1 “yellowed” tubers. Spondylocladium atrovirens 
Harz was isolated from 1 “browned,” 1 “yellowed,” and 2 “not discol¬ 
ored” tubers. The miscellaneous fungi isolated from potato tubers 
varied considerably from year to year, sometimes one and sometimes 
another predominating. So many cultures of Naemosphaera sp. were 
secured from the tubers grown one year, usually from distinctly 
“browned” tubers, that this organism was suspected of being parasitic. 
Inoculation tests, however, gave negative results. The longer the 
potatoes were kept in storage the larger was the number of saprophytic 
organisms which they gave in cultures. Some of the additional miscella¬ 
neous organisms isolated may be indicated by the generic names only_ 
Acremonium, sp., Alternaria, sp., Botrytis sp., Cephalothecium sp., Clado- 
sporium sp., Chaetomium spp. (2), Helminthosporium sp., Mucor sp., 
Penicillium spp. (2), Penola sp., Pestalozzia sp., Phoma sp., Ramularia 
sp., Sclerotinia sp., Sporotrichum. sp., StemphyIlium sp., Stysanus stemo- 
nitis (Pers.) Corda, Vermiculario, sp., Verticillium cinnabarinum r Reinke 
and Berth, and Zygodesmus sp. While some of these organisms may have 
entered sometimes as contaminations in the cultures, most of them had 
penetrated at least slightly into the tissues of the stem end of the tubers, 
usually causing some discoloration there. Seventy-five per cent of these 
tubers were “browned” or “yellowed,” and about 9 per cent were 
“blackened” or had “endrot,” and only 16 per cent were “not discol¬ 
ored.” 
The percentage distribution with respect to the recorded stem-end 
discoloration of the tubers from which “no organisms” were secured is 
in considerable contrast to the low percentages of “no discoloration” 
and the high percentages of distinct coloration in the tubers from which 
the different classes of organisms, as detailed above, were isolated. 
