Minnesota Plant Diseases. 



81 



eral fungi suffocate 

 plants, causing 



death with or with- 

 out true parasitism. 

 A shelf fungus not 

 uncommon in Min- 

 nesota grows on the 

 ground and often 

 envelopes the bases 

 of shrubs or sap- 

 lings with its dark 

 b r o w n fruiting 

 body. When it 

 meets seedlings this 

 envelopment may 

 prevent the further 

 growth of the host 

 and suffocation re- 

 sults. One of the 

 black fungi attacks 

 several kinds of 

 grass plants and 

 prevents the unfold- 

 ing of the leaves 

 and finally causes 

 the death of its host 

 plant. 



Stunting of 

 plants and plant 

 parts. Fungus par- 

 asites in many cases 

 do not produce 

 death but succeed 

 only in stunting the 

 host plant or its 



FIG. 36. Larch tree killed by 

 the parchment pore-fungus 

 (Polystictus pergamenus). 

 The entire tree was killed 

 by this half-parasite. Orig- 

 inal. 



