Sphaerotheca 63 



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disease is described which seriously affected some English straw- 

 berries during that year. Its attacks are described as follows : 

 " This disease makes its appearance in May, in the form of white 

 spots upon the leaves. These gradually spread and cover the leaf 

 surfaces and extend to the fruit, covering it with white filaments, 



which may easily be mistaken for common mould. * * It is most 

 rapid and destructive in its action as the fruit approaches ripeness. 

 As in the case of the allied hop-mildew, which '' runs " with 

 great rapidity in the hop-cones as they approach maturity, the 

 full virulence of the strawberry mildew is concentrated upon the 

 ripening fruit, so that the latter is spoiled before it is fit to pick/' 

 The fungus causing this disease is here identified as S^phaerotheca 

 pannosa^ but it is most probable that S, huniidi was really the 

 species that occurred. The description given of the fungus is 

 rather unsatisfactory {e, g,^ the perithecia are stated to contain 

 several asci) ; the figures of the perithecium, however — one of 

 which show^s a perithecium in section with a single ascus — repre- 

 sent 5. Juiviuli fairly well. It is recommended that imperfect 

 strawberry plants should be sprayed either with ''a weak Bor- 

 deaux mixture, composed of 4 lbs. of sulphate of copper and 3 

 lbs. of lime to 50 gallons of water, or with a composition of 2 lbs. 

 of sulphide of potassium (liver of sulphur) to 50 gallons of water." 



5. huiiiuli illustrates in a striking manner the impossibility of 

 placing any systematic value on the position or the scattered or 

 clustered habit of the perithecia. On Pyriis Aria, Potentilla argeutea, 

 etc., the perithecia are uniformly and distantly scattered over the 

 lower surface of the leaf; on perhaps the majority of the host- 

 plants they are more or less gregarious, often on both sides of the 

 leaf, but frequently only on the upper surface, or commonly they 

 occur on the stem ; on Gilia linearis, etc., the perithecia are closely 

 crowded into dense patches on different parts of the plant, while 

 on Ncillia opidifolia, and in a few other cases, they are so densely 

 caespitose that they more or less encrust in places considerable 

 portions of the stem, petiole, etc. 



Professor Selby has sent me a plant (now in the Kew Her- 

 barium) on ShtpJurdia Canadensis from Michigan, U. S. A., under 

 the MSS. name of Spliacrothcca shepherdiac. The distinctive char- 

 acters were considered to be the crowded habit of the small peri- 



