32 U. S. DEPARTMENT OF AGRICULTURE. 



can be differentiated from early blight and bacterial leaf 

 spot by the presence of the shiny pycnidia and the more 

 common occurrence of spots on the petioles, where the 

 pycnidia are even more conspicuous than on the leaf lesions. 



This disease occurs generally in all celery districts, espe- 

 cially in California, Florida, Michigan, and New York. It 

 is favored by cool, moist weather. 



The fungus overwinters on the seed and in the soil. Late 

 blight spreads in the field during the growing season, and 

 although the original infection takes place in the field, the 

 disease develops and spreads in transit and storage, leading 

 to a soft rot of the leaf blades and petioles. 



Severely affected stock is unfit for market and storage 

 purposes. 



Crop rotation, use of disease-free seed, and proper spray- 

 ing will control the disease. It is advisable to discard 

 severely diseased plants because of the continued develop- 

 ment of the disease at low temperatures. 



Ref. (11); (55). 



CELERY: SLIMY SOFT ROT; BACTERIAL ROT. 



(See Slimy Soft Rot) . 



CELERY: WATERY SOFT ROT; SCLEROTINIA ROT; FOOT ROT; 

 PINK ROT; RIB ROT. 



(See Watery Soft Rot) . 



CELERY: BLACK HEART. 



Cause : Unbalanced water relations. 



In the earliest stages this .disease is marked by shiny, 

 light brown lesions on the blades of the youngest leaves. 

 Very often these are not apparent until the heart of the 

 plant is dissected, since the innermost, most completely pro- 

 tected leaves frequently are the only ones affected. Later 

 the lesions enlarge so as to involve the entire leaf blade, and 

 become very moist and turn black, the whole heart, even 

 the entire stalk, becoming involved if sufficient time is 

 allowed. The advanced symptoms of the disease are caused 

 by bacteria of the Bacillus caratovorus type, which invade 

 the tissue killed by the unbalanced water relations of the 

 plant. 



Black heart originates in the field. Its evil consequences 

 are so well realized by shippers that most affected stock is 

 culled out before shipping. Whether or not stock will de- 

 velop black heart depends upon the plant itself, upon the 

 nature of the soil on which the crop is grown, and upon the 

 weather. In Florida the disease is most severe in late season 

 plants of the Golden Heart variety. 



Ref. (60). 



CELERY: NEMATODE DISEASE. 



(See Nematode Disease). 



