342 STATE BOARD OF AGRICULTURE. 



DISEASES. 



Celery as orown in Mii'lii;inii is not as sns(i'iitil)le lo injury of fini.ucnis 

 diseases as in many otliei- sections of the conn try. The comparatively 

 cool, moist days of the growing season are esi)ecially favorable for the 

 production of healthy, vigorous plants, but in seasons that are unusually 

 warm, these diseases often become very injurious and sometimes ruin 

 entire crops. 



Dani])ing-Off {Rhizoctonia.) This is the most serious disease of the 

 celery plants while in the seed bed. During the first two weeks after 

 the seedlings appear, it is especially apt to attack the plants. This 

 disease causes a decay on the main stem or root just at the surface of 

 the soil, which quickly kills the young seedling. During warm moist 

 weather it is apt to be very injurious, spreading rapidly throughout the 

 bed. In the greenhouse, too much heat, lack of ventilation, and water- 

 ing the ])lants on dark cloudy days, or late in the afternoon, all tend to 

 promote this disease. Thorough ventilation, plenty of light, judicious 

 care in watering, in general, keeping the plants on the ''dry side," tend 

 to ])revent this disease. 



Early Celery Blight (Ccrcospora Apii.) A conuuon disease of celery 

 infecting the foliage early in the season. It first appears as well defined 

 spots on the leaves that soon become so numerous as to cause the leaves 

 to turn vellow and final Iv die. On the dead leaves the disease multi- 

 plies very ra])idly and soon s})reads to the other plants. It does not 

 generally a])])ear late in the season, but plants weakened by this disease 

 are often afterwards attacked by the late blight. Spraying the plants 

 with Bordeaux mixture, as recommended for the late blight will control 

 this disease, the early spraying being especially im])ortant. 



Late Celery Blight {Scptoria Petrosclini.) Of the diseases affecting 

 celery this is generally the most common and serious one. It first ap- 

 I)ears in late summer or early fall as irregular rusty brown spots on the 

 outside leaves, spreading under favorable conditions over the entire leaf 

 surface and to other leaves of the plants, causing a burned a])i)earance 

 to the foliage in a very short time. During unusually warm, moist 

 weather in the growing season, or after the crop is stored, this, disease 

 proves very destructive. Plants set upon poorly drained land or ])lants 

 stunted or weakened by any other means are especially susceptible to 

 it. If the plants are kept growing vigorously and well cultivated they 

 are not as susceptible to it, and are generally able to withstand its 

 effects. However, when the blight has become well established upon the 

 plants it is then too late to a])ply effective remedial measures. The 

 disease may be prevented also by spraying the plants with Bordeaux 

 mixture,* using the 5-5-50 formula, or the ammoniacal carbonate of cop- 

 per spray, beginning when the ]»lants are small, spraying once before 

 lifting them from the seed beds, and continuing the spraying every ten 

 days or two weeks until the plants are ready to blanch by boards. The 

 success of this work will dejK'nd largely upon the thoroughness with 

 which the foliage of the plants is covered, as it is important that all por- 

 tions of the plant be reached by this spray. All diseased plants and 

 refuse left in the field after harvesting should be carried from the land, 

 rather than to turn it under with its spores of this disease to cause au- 



*For details of spraying send to this experiment station for bulletin on'spraying. 



