MARKET DISEASES OF VEGETABLES. 39 



in very dry storage at 32 to 35 F., preferably in slatted 

 crates rather than in bags. 

 Ref. (74). 



ONION: GRAY MOLD ROT; BOTRYTIS ROT. 



(See Gray Mold Rot). 



ONION: NECK ROT. 



Cause: Fungi (Botrytis; Sclerotium). 



This is a semi-watery rot followed by a shrinking and 

 shriveling of the scales. The rot occurs typically as a neck 

 rot in the field, while in storage other regions of the bulb 

 also may be attacked. A gray moldy growth and hard, 

 grayish to black masses of the fungus (sclerotia) develop 

 on the outside of the scales. Neck rot is an example of the 

 gray mold rot of vegetables elsewhere described. 



Neck rot has a tendency to rot all scales uniformly down- 

 ward rather than to follow certain scales as does slimy soft 

 rot. Typical neck rot is especially conspicuous in white 

 onions. In red and yellow varieties, the infection may be 

 confined to the inner scales, and external neck rot symptoms 

 may be lacking. In colored varieties, the soft rotted condi- 

 tion is often found, and the diseased flesh frequently be- 

 comes pinkish, but the gray mold growth and sclerotia are 

 less commonly found. Unlike slimy soft rot, neck rot does 

 not have a foul odor. 



Infection takes place in the field, at or shortly after the 

 harvest. The fungus enters the cut necks of bulbs, and 

 gradually progresses downward. The rot develops in stor- 

 age under moist conditions. Chilled or frozen onions and 

 scallions are subject to neck rot. In chilled onions, the rot 

 is more frequent in places other than the neck. 



If onions show a high percentage of neck rot in storage, 

 transit, or market, disposal for immediate consumption is 

 advised. 



The disease can be controlled by prompt curing of the 

 crop and by storage in a dry place at 32 to 35 F. It is 

 destructive in onion sets as well as in table stock. 



Ref. (48). 



ONION: SLIMY SOFT ROT. 



Cause: Bacteria (Bacillus carotovorus group). 



This is a very soft, mushy rot of the scales, which pro- 

 gresses downward from the neck and is accompanied by a 

 very repulsive odor. Often it is confined to only one or two 

 scales in the interior of the bulb. Lesions may occur any- 

 where, however, especially if the tissues have been killed 

 by sun-scald or bruising. 



Slimy soft rot progresses faster than neck rot, and is not 

 accompanied by a gray mold and sclerotia as is neck rot. 

 Neither does it progress uniformly downward destroying all 



