APPENDIX B 



It is also very common in America. It does not 

 appear to be a serious disease, as it affects only 

 the leaves and does not appear until the latter 

 part of the season after the leaves have apparently 

 begun to mature for Autumn. 



Symptoms. — The symptoms are distinct and 

 striking, large purple blotches on the upper sur- 

 face, often an inch or two or tliree inches in diame- 

 ter. The tissue does not become dead and dry 

 as in the case of the Botrytis blight spots to be 

 described later. The blotch on the underside of 

 the leaf is a peculiar dull brown, as though the 

 epidermis of the leaf had been scorched. In moist 

 weather the centre of the spot below becomes cov- 

 ered with an olive green felt, the stalks and spores 

 of the pathogen. 



Cause. — The disease is doubtless due to a fun- 

 gus which goes by the name of Cladosporium 

 pceonice. 



Control. — Where this disease gives trouble, 

 early removal and destruction of all diseased tops 

 will doubtless be found most satisfactory in pre- 

 venting its appearance another season. The fun- 

 gus most probably passes the Winter in the dis- 

 eased and fallen leaves, from which in the Spring 



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