DISEASES OF CULTIVATED PLANTS 365 
cro and as shown by investigations in Connecticut and our own 
state, it has not always been clear why these losses are so large. 
Recent investigations by this department lead us to believe that the 
green onion neck of white onions handled in this way affords entrance 
for the organism of the rot. 
The sclerotium rot (Sclerotium cepivorum) appears to be the 
most serious, although smudge or anthracnose of the onion ( Vermz- 
cularia circinans) may sometimes cause large losses. Both these rots 
are described under diseases of the onion. The writer believes the 
Sclerotium rot is the larger criminal, and that both may be handled 
by disinfection of the onions immediately after harvest. This dis- 
infection may be carried out as described under the Maine formula 
for Formaldehyde gas treatment, which is: 
2S 
Commercial 40 percent Formaldehyde.............: 3 pounds. 
Potassium Permanganate crystals..... .........- 23 ounces. 
Sufficient for 1000 cu. ft. of space occupied by crates or 
trays. (See page 360). 
The object of immediate disinfection is to prevent the entrance 
of these organisms, particularly the sclerotium rot, through the 
green neck of the newly topped onions. The exuding juices offer 
favorable culture conditions for the fungus to develop. 
When no fumigation is practiced following harvest, the onions 
which are found to be sound and delivered for storage at the close of 
the season may very profitably be treated in this way before winter 
storage. Both these rots are essentially dry-rots of onions. In 
addition, sometimes, we have wet-rot of white onions which may be 
either due to bacteria or to the same fungus as the wet-rot of Globe 
or other onions mentioned below. 
The rots of yellow and red onions are of both the wet-rot and 
dry-rot types, but the wet-rots are much more serious with these 
varieties. Doubtless, as in all vegetables held foralong time in 
storage, we have many cases of wet-rot in onions where some of the 
common decay bacteria are the chief cause. These find entrance 
through wounds, as in topping, and, under conditions favorable for 
their development invade the tissues of the onion and cause decay. 
In addition however, to the wet-rots due to bacteria of unde- 
termined ‘species, we have a specific wet-rot of onions due to 
Fusarium species. This. wet-rot fungus belongs to the same group 
_as the potato dry-rot and is liable to infect soils in which onions are 
grown year after year. Rotted onions will show external develop- 
ments of the pink fungus and may be detected in that way as well as 
by use of the microscope. The chief factors of control with onions 
of this kind, are in the methods of culture followed to produce the 
crop. 
