THE FUNGI WHICH CAUSE PLANT DISEASE 141 



It causes a rot of the grape, much dreaded in Europe, attacking 

 leaves, fruit and stem. The fungus can persist long as a sapro- 

 phyte in the conidial condition. Sclerotia are borne within the 

 affected tissues. On germination they may either produce the 

 conidia directly or form apothecia. Both ascospores and conidia 

 are capable of infecting the grape but infection is much more 

 certain from a vigorous mycelium (see S. libertiana, p. 142). 



Attachment organs, c. f. Fig. 93, which consist of close branch- 

 clusters and seem to be induced by contact of a mycelial tip with 

 any hard substance are present in abundance. Both toxins and 

 digestive enzymes are produced."^' •'^ 



Botrj^s douglasii on pine is perhaps identical with the conidial 

 form of the last fungus (see p. 140) as may also be the Botrytis of 

 Ward's Lily Disease; '° the Botrytis causing disease of goose- 

 berries '' and many others that have been named as distinct 

 species of Botrytis. 



S. galanthina Ludwig, close kin to S. fuckeliana, attacks snow- 

 drops. S. rhododendri Fisch. occurs on Rhododendron. 



The former of these two is supposed to be the ascigerous form 

 of Botrytis galanthina Berk. & Br. but no conclusive proof has 

 been adduced. 



S. Ubertiana Fcl.^' 



Sclerotia from a few millimeters up to 3 cm. in length, black; 

 apothecia scattered, pale, 4-8 mm. or more broad, stem slender; 

 asci cylindric, 130-135 x 8-10 /x, apically 

 very slightly bluish; spores ellipsoid, 

 usually minutely guttulate, 9-13 x 

 4-6.5 Ai; paraphyses clavate. 



This fungus affects numerous hosts. 

 Among the most important on which it 

 causes serious disease are lettuce,^'' '^' ^^' ^ 

 einseng,^' cucumber,'^ carrot, potato, Fig. 96.— s. libertiana. 



, \ ■ u iu„ „; ;„ Sclerotia and apothecia. 



parsley, hemp, rape, various bulbs, zmnia, j^^^^ Stevens ajid HaU. 

 petunia, etc. The white mycelium is 



found superficially and within the host, especially at places 

 where moisture is retained, as between leaves, at leaf axils, etc., 

 also within plant cavities. MicroscopicalVy it consists of long 

 cells branching in a rather characteria^c way. Fig. 97. Within 



