r i2o Diseases of Truck Crops 



TUBERCULOSIS 



Caused by Pseudomonas beticola Ew. Sm. 



Tuberculosis differs from the crown gall by the 

 formation of small tubercules on the root. The part 

 of the root nearest to the tubercule is brown and 

 watersoaked and broken into hollow cavities. The 

 diseased tissue is mucilaginous and stringy when 

 touched. 



The Organism. Tuberculosis is induced by an 

 organism, Pseudomonas beticola. In pure culture of 

 agar the colonies are circular, smootji or wrinkled, 

 and in color are yellow. The organism is rod shaped, 

 single or in pairs, and moves about by means of polar 

 flagella. 



Control. The disease, so far as is known, does not 

 seem to be of any economic importance. Diseased 

 material should be destroyed by fire and the infected 

 soil soaked with formaldehyde made up of one pint 

 of the chemical in twenty gallons of water and ap- 

 plied at the rate of one gallon of the solution to 

 each square foot of space. The organism seems 

 able to gain entrance only through wounds. Care 

 is therefore necessary to prevent cutting or bruising 

 the roots during cultivation or at harvesting. 



SCAB 



Caused by Actinomyces chromogenus Gasp. 



Scab on beets is the same as the scab of the Irish 

 potato. The disease is of the greatest economic im- 



