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ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 



tection for various insects, especially the 

 woolly apliis. 



7. If for any reason cankers are 

 formed and are detected in the winter 

 when very small, the development of the 

 canker may be, in many cases, prevented 

 by shaving off the thin outer layer of 

 the bark. This will allow the cankers to 

 dry out and will prevent, to a large 

 extent at least, the formation of spores 

 in the fall. This method would prob- 

 ably be practical only on young trees, 

 and, in any case, should be considered 

 only supplementary to spraying. 



See Black Spot Canker of Apple. 



Bibliography 



1893-4. Washington State Board Horti- 

 cultural Report, 1893-4, page 69. 

 1900. Cordley, Oregon Experiment Sta- 

 tion, Bulletin No. GO. 

 1900. Cordley, Botanical Gazette, 30. 



page 48-f. 

 1900. Peck, Torry Botanical Club. Bul- 

 letin No. 57. page 21. 

 1904. Lawrence Washington Experiment 



Station, Bulletin No. 66. 

 1906. Cordley, Better Fruit, 1 and 5, 



November. 

 1908. Cate, Oregon Countryman, 1 and 



2, 1 and 3. 

 1912. Jackson. Phytopathology, 2 and 2, 



page 95. 

 1912. Jackson, Oregon Experiment Sta- 

 tion, Crop Pest Report, 1911-12. 

 Bacteriai, Pome Blight. See Blight 

 under Pear. 



Bitter Eott 

 Glomerella rufomaculans 

 The apple bitter or ripe rot is the 

 cause of some of the most extensive 

 losses experienced by apple growers. It 

 is due to a fungus which has been given 

 a number of scientific names, the one 

 by which it is now known being Glom- 

 erella rufomaciilans. The disease occurs 

 throughout nearly all the country east 

 of Kansas and Texas, and is especially 

 destructive in a broad belt from Vir- 

 ginia to Oklahoma. It Is somewhat spas- 

 modic in its occurrence and at times 

 occasions almost total loss. It is stated 

 that in four counties in Illinois in 1900 

 the loss, due to this cause alone, amount- 



ed to $1,500,000, and the estimated loss 

 to the apple crop for the United States 

 during the same year was $10,000,000, 



The fungus lives on many different 

 plants, causing a ripe rot of their fruits, 

 but is best known as causing the bitter 

 rot of apples and the ripe rot of grapes. 

 The first signs of the bitter rot on the 

 apple are to be seen in a slight light- 

 brown discoloration under the skin of 

 the fruit. The spots increase rapidly 

 in size, maintaining a more or less cir- 

 cular outline, and become darker brown 

 in color. Soon the tissues underneath 

 the spots soften and the area seems 

 sunken. When the spots have attained 

 a diameter of about half an inch, small 

 black spots appear beneath the upper 

 surface, through which they finally 

 break, discharging pink masses of spores 

 which are very sticky when moist. These 

 black pustules are usually formed in 

 rings, and as the spots increase in size 

 a number of concentric rings may be 

 seen. The brown coloration of the spots 

 is an indication of the decayed condition 

 of the tissues underneath, and there is 

 usually a sharp dividing line between 

 the sound and the diseased tissues. The 

 fruit is seldom entirely destroyed al- 

 though it is rendered almost worthless. 

 The tissues are at first hard, followed by 

 the breaking down of the cells, and the 

 partially decayed portions usually have 

 a pronounced bitter flavor, from which 

 is derived the name bitter rot. The 

 fruits never become excessively soft and 

 mushy, but often dry into what are 

 called "mummy" fruits. 



It has been claimed that the fungus 

 passes the winter in these fruits, spread- 

 ing the infection the next season. While 

 the spread of the fungus may be favored 

 by the presence of the mummy fruits, 

 yet a more important method has been 

 found in the presence of cankers on the 

 limbs of the trees. These are due to 

 the same fungus as that occurring on 

 the fruits, and their relation to the dis- 

 ease has been well established by Bur- 

 rill and Blair, of the Illinois Station, 

 and Von Schrenk and Spaulding. of the 

 Bureau of Plant Industry. 



