FUNGI IMPERFECTI 361 



L. LATE BLIGHT OF CELERY 

 Septoria Petroselini Desm., var. Apii Br. & Cav. 



Beach, S. A. Celery Septoria. N. Y. Agl. Exp. Sta. Built. 51: 137-141 



1893. 

 Duggar, B. M. Late Blight of Celery. Cornell Agl. Exp. Sta. Built. 132 : 



206-220. figs. 48-60. 1897. 



Habitat relations. The late blight of celery is a comparatively 

 recent disease in the United States, and in Europe it has not been 

 considered a serious celery malady. It is most injurious as a rule 

 during the early autumn, although a few spots of this disease may 

 be seen at any time during the summer where it is at all prevalent. 

 The spots are irregular in outline and of a rusty brown color. How- 

 ever, when the conditions are most favorable for the development 

 of the disease, the fungus may spread over the whole surface of 

 the leaflets without the formation of characteristic spots. 



The late blight is destructive in the field until the plants are 

 " lifted." It may also extend its injuries to the storage coop or 

 cellar. The conditions in the storage cellar may be, during warm 

 days of early winter, most favorable for the spread of the fungus. 

 In a moist, poorly ventilated cellar I have found the pycnidia of 

 this fungus over the surfaces of entire leaves, and the whole plant 

 wilted as a result. 



The fungus. The pycnidia of this fungus are evident soon after 

 the spots turn brown, — as dark papillae more or less in the center 

 of the affected areas. The spores are slightly curved and septate, 

 the septa being usually readily seen only by the use of stains. 



Fresh spores germinate in a few hours in nutrient agar, and 

 transfers may be made to bean stems and any other solid media 

 for a more profuse mycelial development. Moreover, on solid 

 media mature pycnidia may be secured within a few weeks. They 

 develop superficially, and are then composed of loosely woven 

 brown hyphas. The mycelium is entirely distinct from that of 

 Cercospora Apii. 



Control. In the field Bordeaux or ammoniacal copper carbo- 

 nate may be used as a spray, but in the storage cellar it is necessary 

 to pay special attention to all matters of sanitation. When the 

 disease is abundant in the field, additional risk is taken, of course, 

 by placing the crop in storage. 



