318 STATE BOARD OF AGRICULTURE. 



by a mouth of moderate or heavy rainfall, an epidemic of Late Blight de- 

 \elops. 



From a consideration of the rainfall conditions in the first half of the 

 growing season it is possible to predict when spraying is especially nec- 

 essary' — a thing of great importance in view of the high price of Bor- 

 deaux mixture and the necessity of economy in its use. 



A PHOMA DISEASE OF CELERY. 



G. H. COONS. 



For several years, growers of celery have complained of a disease of 

 celery characterized by the rotting of the roots, leaving the plant with 

 a conical, rotted base. Such plants turn yellow and topple over in the 

 row. The disease has probably been referred to before in the literature, 

 for numerous accounts have appeared in which the same pathological 

 picture is described. The fungus Rhizoctonia has been suspected as 

 the etiological factor. 



On rotted plants, the fruiting bodies of a Phoma were discovered. 

 This fungus was obtained in pure culture and typical lesions were ob- 

 tained in inoculation experiments. The etiological relation of the 

 l*homa thus obtained has been fully established. The fungus in cul- 

 ture and pathological habit greatly resembles Phoma apiicola described 

 by Klebahn as producing the ''Scab" of Celeriac. 



The fungus has been found to persist in greenhouses year after year, 

 the disease appearing in the field only in the plants from houses known 

 to be infested. In such cases plants in adjoining fields might be entirely 

 free from the disease. The fungus shows marked susceptibility to high 

 temperatures. Cultures made in mid-summer failed to grow. In this 

 connection it is noteworthy that attack in the field is restricted to the 

 first crop of celery which is set out in early spring. The second crop in 

 rows adjacent to those showing complete failure frequently escapes the 

 disease entirely. 



REPORT OF THE CHEMIST. 



Director R. S. Shaw, East Lansing, Michigan. 



Dear Sir : — I herewith submit a brief report of the work of the Chem- 

 ical division for the year ending June 30, 1917. 



Two changes in the personnel of the staff occurred during the year. 

 Mr. A. E. SmoU resigned early in April to accept a position as chemist 

 witli the Jacob Dold I'acking Company, AVichita, Kansas, and Mr. E. 

 A. De Windt resigned June 1st to enter upon a business career. Both 

 of these voung men rendered valuable service to tlie institution. Tlie 

 vacancies' will* be filled by Percy O'Meara, of the class of 1017, and T. E. 

 Friedemanu who for the past two years has been an instructor in chem- 



