ELEVENTH ANNUAL MEETING. I35 



The question is often raised as to whether we can plant a 

 tree in the same soil from which a tree affected with the 

 yellows has been removed. I would answer emphatically, 

 "yes, if the proper precautions are taken." By digging away 

 some of the old dirt at the root and putting in some new earth 

 and then planting healthy stock, there is little, if any, danger 

 of perpetuating the disease. In some sections of the country 

 trees have been planted for ten years or more in soil from which 

 other trees diseased with the yellows had been taken out, and 

 they were just as healthy and just as productive of good fruit 

 as any trees in the orchard. 



Much might be said respecting the methods pursued in some 

 of the States in combating this disease, but we must pass on 

 to the consideration of some of the other forms of plant 

 diseases. 



In regard to plant parasites that produce disease, there are 

 three main classes, viz : bacteria, slime moulds and thread-like 

 fungi. One of the most important fruit diseases produced by 

 bacteria is the pear blight. In practically all pear-producing 

 regions this disease has been more or less destructive. The 

 organism producing this disease attacks the twigs or branches 

 of the tree and the only known remedy consists in cutting out 

 the diseased parts. Usually, just after blossoming time, you 

 will see the blossoms or the newly formed pears wilt and die. 

 The disease gradually spreads from the blossom to the twig 

 and down the twig into the larger branches, and unless its 

 progress is stopped, the disease often extends down until it 

 reaches and girdles the trunk. In cutting out this disease, 

 care must be taken to cut far enough below the diseased area 

 to remove all the organisms that are capable of producing the 

 blight. Some growers, who have tried to rid their orchards 

 of this pest by cutting out the affected twigs and branches, 

 have found at the end of the season that they had more of the 

 disease than at the beginning. This was owing to the fact that 

 they did not cut low enough to remove all the disease-produc- 

 ing organisms. The organism producing this blight is very 

 readily distributed, being carried, undoubtedly, by the wind and 

 by bees from tree to tree and from orchard to orchard. The 

 organism multiplies very rapidly and usually passes through 

 its life history in a very limited time. It is spread in the tree 



