GLOMERELLA 177 



pinkish mass of conidia on the brown patches until removed 

 by rain, etc. Many observers have proved that when young 

 apples are inoculated with these conidia, apple-rot follows. 

 As a rule not more than two or three diseased patches 

 occur on an apple, these gradually increase in size, and often 

 cover the entire surface. The disease hastens the period of 

 ripening and causes the fruit to fall prematurely. Until 

 quite recently but little was known respecting the life-history 

 of the fungus causing apple-rot. It had been remarked that 

 trees that had been previously attacked were more liable to 

 produce diseased fruit ; it had also been remarked that the 

 disease appeared to spread gradually from an infected tree. 

 Spaulding and Schrenk have shown that the fungus also 

 forms cankers on the branches of apple-trees, and the spores 

 from these cankers bring about the infection of the fruit, a 

 fact which accounts for the fruit high upon the tree first 

 showing the disease. The fungus when present on the 

 branches forms blackened, sunken patches, and the bark is 

 killed for some distance back. The dead bark becomes 

 cracked, or sometimes falls away. The spores of the 

 Gloeosporium stage are produced on these diseased patches, 

 and experiments have shown that the spores from a cankered 

 branch will produce the characteristic rot on the fruit, and 

 vice versa. The cankers occur on last year's fruit spurs, 

 also on branches up to four inches in diameter. The 

 Gloeosporium condition is met with most abundantly in a 

 state of nature, but pure cultures, commencing with the 

 conidia, have resulted in the production of an ascigerous 

 stage, which also occurs on decaying apples, and has been 

 called Glomerella rufo-maculans. 



Gloeosporium stage. Pustules dingy rose-red, arranged 

 concentrically on the brown, depressed patches on the fruit ; 

 conidia oblong or cylindrical, often slightly bent; hyaline, 

 20-30 x 5-6 p ; basidia about equal in length to conidia, 

 simple or forked. 



Ascigerous stage. Produced on decayed apples, etc., 

 forming a stroma, which is often concealed by dark olive 

 mycelium, and contains the immersed, subglobose perithecia ; 

 asci subclavate, fugacious, 55-70 JJL in length; spores 8; 

 hyaline, sausage-shaped, continuous, 12-2 2X3-5 '5 /* 



When the fruit is attacked when quite young, it usually 

 remains hanging on the tree in a mummified condition. All 

 such should be removed, and all fruit that has fallen to the 



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