46 MISC. PUBLICATION 4 4 0, U. S. DEPARTMENT OF AGRICULTURE 



Fusarium yellows (Fusarium- apii Nelson and Sherbakoff and F. 

 apii var. pallidum Nelson and Sherbakoff (193), rootknot, and mo- 

 saic are primarily field diseases; with the occasional exception of the 

 latter they are market factors only indirectly through stunting of 

 the plants. 



Gray mold rot is primarily a transit and storage trouble. 



BACTERIAL BLIGHT 

 (Phytomonas apii (Jagger) Bergeyetal.) 



Bacterial blight of celery has been reported from Indiana, Michi- 

 gan, Minnesota, New York, Ohio, and Pennsylvania, and probably 

 occurs elsewhere in the northern celery-growing regions of the coun- 

 try. The development of the disease is favored by periods of warm 

 rainy weather. Celery harvested from diseased fields is occasionally 

 found on the market with the leaves blemished by the characteristic 

 bacterial blight lesions. 



The chief symptom of the disease is the development of numerous 

 small, irregularly circular spots on the leaflets. At first these are 

 yellow, later turning to a rusty brown with a yellow border or 

 halo around them. They may remain as numerous individual spots, 

 or they may coalesce to cover large areas of the leaflets. The spots 

 differ from those of early blight (p. 50) and late blight (p. 51) 

 in that neither ashen-gray mold nor black fruiting bodies are present. 



The disease can be successfully controlled in the seedbed and 

 in the field by spraying with bordeaux mixture or dusting with 

 copper-lime dust, (See Celery, Late Blight, p. 51.) 



(See 170, 179, 194,223.) 



BACTERIAL SOFT ROT 



(Erwinia carotovora (Jones) Holland) 



OCCURRENCE, SYMPTOMS, AND EFFECTS 



Bacterial soft rot is an important market disease of a wide variety 

 of vegetable commodities. Wounded or bruised tissues are readily 

 affected and the causal organism is a secondary invader of tissues 

 weakened or killed by other diseases. On celery the decay commonly 

 follows such troubles as late blight, early blight, freezing injury, 

 black-heart, and bruises and injuries of all sorts: it frequently is 

 of considerable importance on stock that has not been promptly 

 stored or shipped after harvest. 



The disease at times causes heavy field losses. If only the outer 

 leaves are affected these can be stripped off during harvesting and 

 packing with only a minimum of loss. Occasionally, however, the 

 disease occurs as a crown rot or heart rot, in which case the plant 

 soon becomes commercially worthless and serious losses are incurred. 



The first symptoms of the decay are a water-soaked appearance and 

 softening of the affected tissues. These areas soon turn brown and 

 become very mushy hut the epidermus remains intact (pi. 14. A. B). 

 Although in sonic vegetables the decayed tissues have a slimy con- 

 sistency and an offensive odor, in celery neither symptom is ordi- 



