644 



THE FUNGI WHICH. CAUSE PLANT DISEASE 



Fig. 434.— lUospo- 

 rium maculicola. 

 After Saccardo. 



or mottled with gray and with a small gray spot near the center, 

 5-15 mm. in diameter; sporodochia hypophyllous, minute, gelat- 

 inous, yellow-amber, becoming black, spherical, becoming discoid 

 or irregular, 150-160 /x in diameter; conidio- 

 phores branched; conidia oblong, 1-3.5 x 4 /i. 



It is said by Sheldon '^^ to be one of the most 

 common and destructive causes of leaf spots of 

 the apple often resulting in nearly complete de- 

 foliation. In the centers of the leaf spots other 

 spots bearing other species of fungi are often 

 found, leading to the thought that perhaps the 

 Illosporium in such cases results from secondary infection in the 

 wounds made by the earlier fungus. The sporodochia are hypo- 

 phyllous, often hidden by the normal pubescence of the leaf. 



Volutella Tode (p. 641) 



Sporodochia discoid, regular, margin ciliate, sessile or stipitate; 

 conidiophores usually simple ; conidia ovoid to oblong. 



Some seventy species. 



V. leucotricha Atk. 



Sporodochia convex-discoid, white to pale flesh-color; setae few, 

 filiform, few-septate, subhyaline; conidiophores densely fasciculate, 

 filiform; conidia oblong. 



On cuttings in greenhouses. 



V. fructi S. & H. 



Spots on the fruit, circular; sporodochia, numerous in concentric 

 circles, subcuticular, 

 erumpent, elevated 200- 

 250 M, 150-400 M in 

 diameter; mj'celium 

 black; setse distributed 

 throughout the sporodo- 

 chium, black, to 3- 

 septate, acute, smooth, 

 100-400 X 5-8 n; co- 

 nidiophores elongate, hyaline, simple, 25-35 x 3 m; conidia 

 smooth, oblong-fusoid to falcate-fusoid, hyaline or sub-olivaceous, 

 17-23 X 2.5-3.5 ii. 



Fig. 435.- 



-V. fructi. Sporodochia in section. 

 After Stevens and Hall. 



