THE FUNGI WHICH CAUSE PLANT DISEASE 201 



M. stysanophora Mat. is said to be an ascigerous stage of 

 Dematophora glonierata, cf. p. 230, so injurious to the grape. 



Nectria Fries (p. 197) 



Stroma absent or tubercular, fleshy, bright colored; perithecia 

 single, or gregarious, on or in the stroma or among cottony hyphae, 

 globose or ovate, walls fleshy, yellow, red or brown, smooth or 

 hairy; ostiole papillate or not; asci cylindric or clavate, 8-spored; 

 spores elongate blunt or pointed, 

 hyaline, rarely red, 2-celled, form- 

 ing conidia in the ascus; paraphyses 

 usually none. 



As conidial stages occur the form 

 genera Cephalosporium, Tubercu- 

 laria, Fusarium, Spicaria, Fusidium 

 and Chsetostroma. Much doubt 

 exists as to specific limitations, and 

 as to the life histories of the species. 

 Some two hundred fifty species have 

 been described. Several are cred- 

 ited with causing serious diseases, 

 most of them occurring as wound parasites and unable to effect 

 entrance into soimd tissue. Other species are pure saprophytes 

 and harmless. 



The genus Nectria is divided into seven sub-genera, which are 

 frequently given generic rank, as follows: 



Fig. 142. — Melanospora. K, peri- 

 thecium ; L, asci ; M, spores. After 

 lindau. 



Key to Subgenera of Nectria 



Spores smooth 

 Perithecia smooth 



Stroma fleshy 1. Eunectria, p. 202. 



Stroma a cottony subiculum 2. Hyphonectria. 



Stroma usually absent; perithecia 



scattered. 3. Dialonectria, p. 205. 



Perithecia hairy 4. Lasionectria. 



Perithecia scaly 5- Lepidonectria. 



Spores tuberculate 6. Cosmonectria. 



Spores appearing striated, golden brown ... 7. Phaeonectria. 



