370 
Joumal of Agricultural Research 
Vol. XXX, No. 4 
ficial results. Even in the best por¬ 
tion of Lot I (crates Nos. 1 to 6), where 
only 9 per cent neck rot appeared in 
the control, the amount of infection was 
reduced two-thirds or more. In the 
dampened portions of Lot I (crates 
Nos. 7 to 12) drying by natural agen¬ 
cies (crate No. 8) reduced infection 
from 50 to 27 per cent, but artificial 
curing reduced the disease to the al¬ 
most negligible amount of 7 to 10 per 
cent. Thus, by the latter treatment, 
damage due to the exposure to a week’s 
damp weather was prevented. 
In Lot II, where the amount of dis¬ 
ease reached much higher proportions, 
the damage from neck rot was reduced 
to a negligible quantity by means of 
artificial drying. There was almost a 
total loss when this lot was exposed to 
damp conditions (crate No. 16), but 
immediate artificial drying again pre¬ 
vented such damage (crate No. 15). 
Representative amounts of healthy 
onions at the end of the storage period 
from crates 13, 14, and 16 are shown 
in Plate 2. 
In comparing the amount of neck rot 
in crates exposed to drying for various 
intervals it is noteworthy that in each 
case (crate No. 2 and crate No. 9) prac¬ 
tically the maximum reduction of dis¬ 
ease was reached within two days’ ex¬ 
posure. By forced circulation of warm 
dry air, the length of treatment can 
undoubtedly be reduced much more. 
EXPERIMENTS WITH LARGE BULBS 
Two experiments were conducted 
with large bulbs, Lot III in 1917 and 
Lot IV in 1923. Lot III consisted of 
the oversize bulbs sorted out at harvest 
time from the sets which comprised 
Lots I and II. A few of these bulbs 
showed signs of incipient decay before 
they were placed in the drier. Evi¬ 
dence of such early infection is shown 
in Plate 1, A. The exposure to warm, 
dry air resulted in practically all cases 
in thorough dehydration of the dis¬ 
eased tissue in such bulbs. Observa¬ 
tion throughout the storage period 
showed that in practically all cases 
this treatment checked any further 
advance of the fungus. The results 
with dried and untreated portions of 
Lot III are given in Table V. Almost 
complete elimination of loss from neck 
rot was attained. Typical bulbs from 
the dried lot in which desiccation of the 
slightly decayed neck occurred are 
illustrated as they occurred at the end 
of the storage period in Plate 1, B. 
Completely decayed bulbs, typical of 
the untreated lot, are shown in Plate 
1, C. 
Lot IV consisted of large White 
Globe onions grown on old onion soil 
at Racine, Wis., in 1923. They were 
harvested about September 10 and 
stacked in the field in slatted bushel 
crates for about three weeks before 
being placed in the drier on October 2. 
At the latter date there was evidence 
of neck rot in its early stages in a goodly 
percentage of the bulbs. In these the 
decayed tissue dried down in the same 
manner noted for Lot III, and in the 
majority of cases this resulted in a com¬ 
plete check of the fungus. The length 
of exposure and the temperature 
during the period of exposure with the 
final notes taken on December 14, 
after about two-months’ storage are 
given in Table V. Although the neck 
tissue of large bulbs is naturally more 
difficult to dry out satisfactorily, it was 
possible to accomplish this with forced 
circulation of air for two or three days. 
The air current was maintained at room 
temperature, except for three to six 
hour intervals, during which the tem¬ 
perature was raised to 40° C. or 44° C. 
The amount of actual decay due to 
neck rot was in each case reduced to 
an almost negligible quantity compared 
with that which developed in the 
control. The percentage of bulbs 
showing complete check of incipient 
neck-rot infection is also significant. 
Of course, more prompt drying of 
bulbs after harvest would have elimi¬ 
nated the incipient decay. It is valu¬ 
able, however, to know that with 
proper treatment the disease can be 
checked even after the signs of the 
disease have become evident. 
CONCLUSIONS 
The data presented, together with 
field observations over a period of years, 
show that in the Middle West and prob¬ 
ably in all of the Northern States sev¬ 
eral factors enter into the determination 
of the amount of infection by the 
mycelial neck rot disease. Weather 
conditions preceding and during har¬ 
vesting and curing of crop are un¬ 
doubtedly influential, and more study 
of their exact relation would be desir¬ 
able. It is apparent that the state of 
maturity of the neck tissue of the bulbs 
at harvest is an important factor. 
Removal of tops may increase infec¬ 
tion, but it is evident that this opera¬ 
tion may under some conditions have 
little influence in the case of white 
varieties. The grower is unable by 
any ordinary means to so handle the 
crop as to prevent neck-rot infection, 
and this is especially the case with the 
white varieties, which are much more 
susceptible than colored varieties. 
