446 DISEASES OF CULTIVATED PLANTS 



present for some time, numerous small, black stromata are 

 formed in the peripheral portion of the bark. These stromata 

 possess labyrinthiform cavities in their interior, the walls of 

 which are lined with conidiophores bearing filiform, curved, 

 hyaline, continuous conidia, 33 x 1-5 //. 



These conidia escape in the form of yellowish, mucilaginous 

 tendrils through one or more mouths or openings in the 

 stroma. This disease must not be confounded with the 

 gooseberry collar rot caused by Botrytis cinera, which is much 

 more prevalent in this country. In the latter disease the 

 black bodies present in the bark are true sclerotia ; solid, 

 externally black, inside white, and after a period of rest give 

 origin to the conidial Botrytis form of fruit. 



Hall, C. J. J. van, A fin. Mycol,, 1, p. 503 (1903). 



CYLINDROSPORIUM (Unger.) 



Spore-masses formed under the epidermis, white or pallid, 

 discoid or subeffused ; conidia filiform, continuous, hyaline, 

 often flexuous. 



Considered as conidial forms of Entyloma. 



Cherry and plum leaf blight. The injury caused by 

 Cylindrosporium padi (Karst.) is pretty generally distributed 

 in Europe, and of late has become too well known in the 

 United States. The foliage is the part that suffers, and is 

 most prevalent on nursery stock, but older trees are also 

 attacked. About the end of May minute, pale, or reddish 

 spots appear on the leaves ; these increase in size, become 

 brown, and eventually the tissue of the diseased patches dry 

 up and fall out, leaving holes in the leaves. When the 

 attack is severe, the leaves fall quite e.irly in the season. In 

 the case of cherries the leaves usually assume autumnal tints 

 before falling, whereas plum leaves fall while yet quite green. 

 Great variability exists as to the susceptibility of different 

 varieties to this disease, the English morello cherry being 

 amongst those that suffer most. 



Forming angular, brownish spots on both sides of the leaf, 

 pustules hypophyllus, covered at first by the raised epi- 

 dermis, conidia filiform, flexuous, hyaline, oozing to the 

 surface, 4S-62 X 2 /<. 



