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ASCOMYCETES. 



Sphaerotheca pannosa Wallr. (Britain and U.S. America). 

 The Eose-niildew. The mycelium forms a thin white coating on 

 the leaves, and is nourished by lobed haustoria inserted into 

 the epidermal cells. Young leaves or buds when attacked 

 become more or less deformed, their function is interfered with, 

 and death may result. In this way great damage is done in 

 rose-gardens. This parasite also attacks young leaves and fruits 

 of peach and apricot. 



Fio. 69, — Sphaerotheca pannosa on Peach. The mycelium and couidiophores 

 are shown on the epidermis of a leaf. (After Tulasne.) 



Hose-mildew is propagated during summer by ovoid, uni- 

 cellular conidia abjointed in acropetal series from erect couidio- 

 phores. The perithecia have short simple appendages, and 

 contain elliptical spores. 



The disease may be combated by "sulphuring"; according to 

 Pdtzema-Bos, spraying with Bordeaux mixture has also shown 

 good results. 



