THE FUNGI WHICH CAUSE PLANT DISEASE 



267 



The mycelium hibernates in limb cankers and in mummified 

 fruit.=^^ 



It is impossible morphologically to distinguish the conidial 

 stages of many species of Glceosporium and CoUetotrichum grow- 

 ing on a great variety of hosts, and much inoculation work has 

 been done to ascertain the relationships existing between these 

 many forms. Thus the author -"*" in Dr. Halsted's laboratory 

 made inoculations as indicated in Fig. 367. Southworth cross 

 inoculated a Glceosporium from 

 grape to apple and from apple 

 to grape; Stoneman from 

 quince to apple.-" Even such 

 cultures give little evidence of 

 difference between these forms 

 and it usually is impossible to 

 distinguish between the conidial 

 forms on either morphological 

 or biological grounds. 



Some group under Glomeralla 

 rufomaculans as its conidial 

 forms, what were formerly 

 known as Glceosporium fructi- 

 genum, G. rufomaculans, G. 

 versicolor and G. laticolor. 



Further studies of the ascig- 

 erous stages have led to con- 

 solidation rather than to seg- 

 regation of species. Thus an 

 ascigerous stage, a Glomer- 

 ella, was obtained in pure 

 culture from the following conidial forms by Shear and 

 Wood:"^ 



G. rufomaculans from grape, G. fructigenimi from apple, G. 

 sps. from cranberry, G. elasticse from Ficus (see p. 544) a Glceo- 

 sporium from Gleditschia, one from Ginkgo, CoUetotrichum 

 gossypii from cotton (see p. 271) and C. lindemuthianum. (See 

 p. 547) from bean. These authors after careful study of these 

 perithecia and cultures conclude that: "in the present state of 



Fig. 196. — Plate culture of G. rufomacu- 

 lans showing perithecia-bearing 

 masse.s. After Spaulding and von 

 Schrenk. 



