8 4 



DISEASES OF TREES 



FIG. 29. A vine that has been killed by 

 D. necatrix, and afterwards kept for a 

 long time in a moist chamber. The fila- 

 mentous mycelium, a, assumes the char- 

 acter of white Rhizoctonia strands, , 

 which anastomose, c c . At d and e rhizo- 

 morphs grow out from the interior. 



FIG. 30. A sycamore infected by 

 D. iiecatrix. The portion above 

 ground is represented some four- 

 teen days anterior to the rest. 

 The plant is enveloped in the 

 white woolly mycelium, a ; on 

 the subterranean portion Rhizoc- 

 tonice consisting of dark my- 

 celium, b b, are to be seen. Nu- 

 merous sclerotia, c, project from 

 the cortex. 



