NECTRIA 



179 



brittle. Experiments have proved that the ascospores when 

 placed on the young leaves, germinate, enter the tissues, and 

 give origin to the disease. 



Ascigerous form. Stromata flattened, developed on the 

 under surface of the leaf, reddish, then orange-brown, ostiola 





FIG. 46. Poly stigma rubrum. T, diseased plum leaves; 

 2, section through stroma showing perithecia ; 3, asci containing 

 spores ; 4, spermatia produced in spermogonia. Fig. i reduced; 

 remainder highly mag. 



sunk in the tissue ; asci clavate ; 8-spored ; spores elliptical, 

 obtuse, straight, subhyaline, iox6/*. 



Conidial form {Libertella rubra, Bonor.). Spermatia 

 filiform, slightly thickened at one end, curved, 30 //. long. 



Prillieux, Malad. des Plantes Agric., 2, p. 91 (1897). 



B. Spores hyaline, \-septate ( = 2-celled). 



NECTRIA (FRIES.) 



Perithecia distinct, clustered, or scattered, sometimes pro- 

 duced on a fleshy stroma that has previously borne conidia, 

 fleshy or sub-membranaceous, clear coloured, usually red or 

 orange ; asci cylindric-clavate, 8-spored ; spores hyaline, 

 elongated, i -septate. 



