SCLEROTINIA. 



259 



cowberry shoots, the stomata being always avoided. In less 

 than three weeks conidia are produced. 



The mode in which the germ-tubes attack the host-plant is 

 very remarkable. Woronin says : " The germ-tubes developed 

 from the ascospores grow inwards towards the vascular bundles 

 of the host-plant and enter them ; then they continue to 

 develop, but now in the opposite direction from the interior of 

 . the plant towards the periphery. Here a peculiar phenomenon is 

 exhibited, the fungus exerts its injurious effects on the surrounding 

 tissues of the host-plant, then, having killed these, it utilizes 



Fig. 137. — Sclerotinia baccarum on Vaccinium Myrtilliis. Young shoot of Bilberry 

 with deformed branch bearing white conidial patches on its lower side ; also a 

 withered leaf. A, Conidial chains, and a poi-tion enlarged. B, Shoot with an 

 upper healthy ripe berry and a lower mummified one. C, Peawa-cup developed 

 from a sclerotium. J), Ascospores ; the smaller incapable of germination, another 

 germinating and giving off sporidia. (After Woronin.) 



them as food-material." "Finally, the germ-tubes penetrate 

 between the elements of the outer rind already killed, and there 

 develop to a stroma-like cushion of large-celled pseudo- 

 parenchyma from which the chains of conidia emerge through 

 the ruptured cuticle." 



(Saccardo also mentions Scl. oreophila Sacc. on leaves of Vaccinium 

 Viiis-Idaea.) 



Sclerotinia oxycocci Wor. The sclerotium disease of the 

 true cranberry ( Vaccinium Oxi/coccus). The spores of this species 

 are smaller than those of the preceding; each ascus contains four 



