THE FUNGI WHICH CAUSE PLANT DISEASE 



143 



Botrytis conidial stage but the results of much careful work deny 



Recent tests by Westerdijk ■'" indicate the absence of such 

 biologic specialization in regard to hosts as 

 is found in the Erysiphe and elsewhere. 



S. nicotianae Oud. & Kon.'*'' ^- parasitize;; 

 the leaves and stems of tobacco. It is 

 possibly identical with S. libertiana. 

 S. trifolioruin Erik.^^-^" 

 In general this resembles S. libertiana 

 with which it is by some regarded as iden- 

 tical; sufficient evidence has, however, not 

 been adduced to prove them the same. 

 The sclerotia, varying in size from that of 

 a mustard seed to a pea, are found in the de- 

 cayed tissue, or as larger fiat surface sclero- 

 tia. No conidia except 

 the functionless gonidia. 

 Unknown on clover. 



S. bulborum (Wak.) 

 Rehm *^ which is very 

 similar to S. trifoliorum 



and without known conidia grows on hyacinth, 

 crocus, scilla and tuhp. Cross infections be- 

 tween hyacinth and clover have not, however, 

 been successful and the species may be dis- 

 tinct. A sterile form, Sclerotium tuliparum, 

 found on the tulip may also belong here. 



S, tuberosa Fcl. is found on wild and culti- 

 vated anemones. 



Several other species of the genus, arriong 

 them S. alni Maul, S. betulae Wor., S. aucupa- 

 riae Ludw, S. crategi Magn., are found on 

 Ericaceae, Betulacese, Rosacese, Graminea, etc., but they are not 

 of sufficient economic importance to w^rant further notice 

 here. 



Fig. 99.— Cultures uf .scle- 

 rotinia from tobacco on 

 potato agar, showing 

 sclerotia. After Clinton. 



Fig. 100.— C. senig- 

 inosum. /. ascus; 

 K, ascospores; L, 

 conidia. After 

 Rehm and Bre- 

 feld. 



