446 ANNUAL REPORT OF THE Off. DoC. 



MR. COLLINGWOOD: Is there any difference in the keeping qual- 

 ities between sod grown apph's and clean culture fruit? 



MR. POWELL: Our experience has been that there is no differ- 

 ence when trees are of the same age, and all other conditions are the 

 same, but on young trees they will not keep so well from cultivated 

 land. 



DKSEASES OF ORCHARD TREES AND FRUITS. 



By M. B Waite, Path»logist in Charge of Investigations of Diseases of Fruits, V. S. Department 



of Agriculture. 



Introduction. 



The subject assigned to me by the Secretary is so broad that I 

 am obliged to select from it for discussion some particular branches 

 in order to keep my paper within reasonable limits. For this reason 

 I have selected certain orchard diseases more or less serious in this 

 part of Pennsylvania, and in connection with which there is likely 

 to be more or less interest on the part of the members of this So- 

 ciety. I will, therefore, take up for rather brief discussion, pear 

 blight, on both the apple and pear, apple scab, apple leaf blight and 

 spraying for the same, together with a discussion of russetting due 

 to Bordeaux mixture; also peach yellows, little peach and the brown 

 rot of peaches, plums and stone fruits, three of the leading peach 

 diseases. Each of these subjects for full discussion requires an 

 hour's lecture and I can, therefore, only give you a few important 

 points on each of these diseases. 



Pear Blight. 



Description. — The well-know'n bacterial pear blight caused by 

 a tiny bacillus is one of the prominent orchard diseases in this part 

 of the country. It attacks particularly the pear and the apple, but 

 also affects the quince, the Siberian crab apple, the wild crab apple, 

 the Hawthorne, and practically all the fruits of the pome family. 

 The germs producing this disease enter the tree in three different 

 ways: First and most commonly, through the blossoms, being dis- 

 tributed from flower to flower and tree to tree very widely through 

 bees and other flower visiting insects; second, through the tender 

 tips of growing shoots, including the water sprouts at the bases of 

 th'e trees; and third, directly into the fleshy bark. Infections of this 

 latter type are few in number but result in a very serious form of 

 the blight. The amount of damage resulting from an infection 

 may vary enormously. Thousands of infections simply kill the 

 blossoms cluster or a few inches of the top of a growing twig. On 

 the other hand the blight may run down on to large branches or 

 run clear to the ground, killing the whole tree, or it may spread 

 from a lateral infection, doing more or less damage. The spread 

 of the disease, the number of infections and the amount of ex- 



