2G2 STATE BOARD OF AGRICULTURE. 



can be substituted for the meicuric chloride. The advantage of mercuric 

 cyanide as a chemical for this purpose comes in its great solubility and 

 also from the fact that it is not corrosive to metals. Potato treatments on 

 a large scale require such a large equipment of l)arrels, tanks, etc., if 

 treatment is to be done rapidly, that many farmers find the matter ex- 

 ceedingly onerous. If mercuric cyanide can be furnished at all cheaply 

 to farmers, it will be a great advantage for their metal stock tanks can 

 be used for treatment — the same to be carefully rinsed before using for 

 the ordinary purpose again. Work with mercuric cyanide is being 

 continued. 



STATE CELERY WORK. 



For some yenva the Experiment Station has worked on the celery diseases 

 of the State. Attention in the last two years has been given largely to 

 root diseases. The disease known as celery stimt has been kept under 

 observation and selections of apparently resistant plants made. In no 

 case has it been possible to winter over any of the selected plants. Plants 

 which were growing in thoroughly sick soil and which were apparently 

 free from disease when planted in the greenhouse or in the cold frame, rot 

 in a month or two, indicating a partially diseased condition or an outgrown 

 diseased condition at the start. Search for resistant plants and the attempt 

 to winter them will be continued. 



Since our first surveys of the prevalence of celery stunt the disease 

 has been found in many other locations in the State. The disease is known 

 now from every muck area of the State, although in all but Kalamazoo the 

 disease is localized in its attack. The wide spread of the disease has been 

 accomplished by the sale of diseased seedlings — a trade which is very 

 brisk among market growers, especially in years when freezing or drought 

 destroys seed beds in any given locality. 



Golden Self-blanching celery is chiefly affected by the stunt, and in 

 ordinary years Easy Blanching celery can be grown at a profit in diseased 

 soil. Around Kalamazoo, the Easy Blanching is the chief celery grown. So 

 far it has been marketed at a fair price. 



Reports from other northern states indicate that the Michigan situation 

 in regard to celery stunt is duplicated with them. It is evident that the 

 Golden Self-blanching celerj^, which is the plant most highly prized on the 

 markets is becoming exceedingly scarce. It seems extremely probable that 

 in a very short time high lands can profitably be turned to the growing 

 of this plant, by proper irrigation, and by the taking of proper precautions 

 to prevent the entrance of this disease. 



PHOMA ROOT-ROT OF CELERY. 



Last year's report contained a short abstract of work done by the 

 writer upon this interesting disease of celery roots. Last year, Mr. C. W. 

 Bennett undertook fuller study of this disease. He has done most ex- 

 cellent work and great y advanced our knowledge of the disease. After 

 verifying the work previously done in the laboratory, Mr. Bennett has 

 worked out details of methods of infection, has studied the causal organism 

 in pure culture and determined its physiological relations under various 

 growth conditions. 



Most interesting and important as a contribution to the science of 

 plant pathology are the results obtained in the loss of virulence. Mr. Ben- 



