MARKET DISEASES OF VEGETABLES. 29 



in, proceeding either from the outside or inside, and the 

 head rots rapidly with a very offensive odor.. 



This disease occurs in all cabbage-growing regions. Infec- 

 tion takes place in the field. The bacteria enter the plant 

 at the margins of the leaves, proceed downward through 

 the veins to the main stalk, and then upward into the head. 



The disease develops in transit and storage. Affected 

 stock is very subject to secondary rots, and as a result is a 

 menace to healthy stock. 



Control of the disease in the field consists of seed disin- 

 fection, seedbed sanitation, and crop rotation. Severely 

 affected stock is unfit for food. It is not advisable to store 

 or ship slightly affected stock. 



Ref. (61); (26). 



CABBAGE: FREEZING INJURY. 



Cause : Exposure to low temperatures. 



Freezing injury is marked by a glassy yellowish appear- 

 ance of the affected tissues. 



Affected stock, if thawed rapidly in a warm place, or if 

 kept in a moist atmosphere, is soon destroyed by slimy soft 

 rot. Therefore it is not suitable for storage. It is generally 

 assumed that cabbage can be frozen once or twice, if thawed 

 out properly, without any injury except a slight shrinkage 

 and flabbiness. The outer leaves can be frozen and thawed 

 without injury, but if the freezing extends to the interior 

 tender tissues, these are killed and, upon thawing, fall a 

 ready prey to slimy soft rot. 



Generally all frozen heads which do not show a glassy, 

 yellowish ring in the tissue of the stalks upon thawing are 

 fit for marketing for immediate consumption. This is not 

 a positive test, however, since not all affected heads show 

 a discoloration or decay of the stalk. 



CABBAGE: LEAF SPECK. 



Cause : Not known ; probably non-parasitic. 



Leaf speck consists of small, sharply-sunken, shiny, brown 

 spots or black specks which may occur on all leaves of an 

 affected head. Speck can be differentiated from black leaf 

 spot by the smaller size of the spots, and by the absence of 

 concentric rings, or any black fungous outgrowth. 



Leaf speck occurs in cabbage from all sections, and is very 

 severe in some Florida stock. 



Nothing is known about the cause, point of origin, and 

 conditions favoring the development of the disease. 



No control measures are known. It is advisable to sort 

 cabbage carefully because affected heads have a lower 

 market value. 



CABBAGE: SUN-SCALD. 



(See Sun-Scald). 



