136 THE CONNECTICUT POMOLOGICAL SOCIETY. 



through the sap, usually downward, but sometimes upward in 

 the twigs or branches. Of course a few of these in a tree or 

 twig would do very little damage, but the organism multiplies 

 so rapidly that the danger of ruining the tree and of infecting 

 surrounding trees is great unless prompt measures are taken for 

 its suppression. The pear blight represents only one of many 

 forms of plant disease produced by these small organisms or 

 bacteria. 



The second class of disease-producing organisms is repre- 

 sented in the disease known as the crown gall. It is possible 

 that the disease is not serious in Connecticut or perhaps it has not 

 appeared here at all, but in some states it has become a serious 

 pest. It should be looked for first in the nurseries, as it is 

 more quickly and easily found on nursery stock. In some 

 sections it is not uncommon to find it on the older trees. When 

 this disease attacks a tree it produces one or more galls or knots 

 just at the juncture of the roots and trunk. In some instances 

 the galls appear farther down on the roots or several inches 

 above the surface of the ground. The organism producing 

 this disease has been worked out by Prof. Toumey of the Yale 

 Forestry School and, as already indicated, is one of the slime 

 moulds. This peculiar mould works into the tissues of the 

 root and produces enlargement at the point of attack. These 

 knots injure the appearance of the nursery stock and conse- 

 quently interfere with its sale. The affected trees are usually 

 shorter lived and less productive than trees produced from 

 healthy stock. All fruit trees seem to be susceptible to this 

 disease ; hence a careful examination of the stock should be 

 made before planting, and all affected trees should be discarded. 

 Whether the crown gall' is serious or is not serious in this 

 State, it is well to be on the lookout for it. In some sections 

 it has caused a great deal of damage, and there is no reason 

 why it will not thrive here if it is once established. In some 

 stages of the disease, it has been thought that these galls could 

 be cut out of the trees and the disease removed by that method, 

 but thus far this practice has been without satisfactory results, 

 since the galls soon grow again. It is well to prevent, if 

 possible, the propagation of these trees, and only healthy stock 

 should be relied upon for the orchard. 



