58 EXPEKBIEXT STATION. l-Ian. 



CROWN GALL. 



BY G. K. STONE. 



For many years a disease known as crown gall has affected 

 raspberries in this State. The disease is characterized by large 

 abnormal swellings or gall formations near the crown of the 

 roots, and is well known to all raspberry growers. Easpberry 

 plantations are almost invariably affected with crown gall after 

 being set out for a few years, and in the course of time these 

 galls affect the plant to such an extent that the crop is no longer 

 l)rofitable, and it becomes necessary to start a new plantation. 

 In recent years other plants have become affected with crown 

 gall, which is becoming more common on the roots of our fruit 

 trees, notably the apple, pear and peach, although until five or 

 six years ago galls on fruit trees were very rare in ]\rassachu- 

 setts ; at least, if they existed at all they were limited to certain 

 areas, and were brought into the State on infected nursery stock. 



It is quite certain that the germs of crown gall are not in- 

 digenous to our soil, and in all cases the disease has been intro- 

 duced through nursery stock from outside the State. Apple 

 trees have been grown in the State for years without being af- 

 fected, and it is reasonable to suppose that they may be grown 

 to-day in most of our soil without infection, providing clean 

 stock is secured when planting an orchard. However, when 

 crown gall is once introduced into an orchard it is difficult to 

 prevent even clean stock from becoming infected. The writer 

 knows of a large tract of land, which was, until three years ago, 

 free from crown gall, where to-day it is impossible to plant even 

 seedlings Avithout their becoming infected. The soil in this in- 

 stance was first infected by imjiorted stock ; and undoubtedly by 

 the use of cultivators, etc., the disease germs have been spread 

 over a large part of the cultivated area. The organism causing 



