294 PLANT DISEASES 



CHERRY LEAF SPOT 

 (jCoryneum beyerinckii, Oud.) 



This fungus attacks not only the cherry but also the 

 peach, apricot, almond, and plum. Not unfrequently in 

 spring the young leaves show red or rosy spots on the 

 under surface; such are also often present on the young 

 shoots. At a later stage the tissue at diseased points be- 

 comes brown, and dies, and the conidia of the fungus are 

 produced in minute black spots grouped on the dead 

 portions, which finally as a rule fall away, leaving the 

 leaf perforated. The diseased spots on the twigs are 

 usually elongated. When the fruit is attacked the flesh 

 dries up to the stone. 



Late in the season a second form of fruit pycnidia 

 appears on the diseased patches on the twigs, and on 

 mummified cherries an ascigerous condition has been de- 

 tected the following spring. These are supposed to belong 

 to the Coryneum, but the point has not yet been definitely 

 settled. The ascigerous condition has received the name 

 of Ascospora bezjerinckii, Vuill. A certain amount of gum- 

 ming sometimes takes place on branches attacked by the 

 fungus, but whether caused by the parasite is not known 

 with certainty ; Vuillemin thinks not. 



PREVENTIVE MEANS. No methods have been recorded, 

 but probably spraying at the time when the leaf-buds are 

 expanding would prove beneficial. 



Oudemans, Hediv.^ 1883, p. 113. 



Vuillemin, Journ. de Bot., vol. ii. p. 255. 



Prillieux, Malad. des Plantes Agric., vol. ii. p. 337, figs. 



