288 DISEASES OF CULTIVATED PLANTS 



Juniper leaf spot (Keithia tetraspora, Sacc.) forms minute 

 dark spots on living leaves of the common juniper. As a 

 rule only one or two spots are present on a leaf, resembling a 

 Puccinia in habit and appearance. 



Spores broadly elliptical, clear brown at maturity, divided 

 into two cells of very unequal size, 25-30x15-17 p. Para- 

 physes pear-shaped and brown at the tip. 



ROESLERIA (THUM. and PASS.) 



Ascophore stalked, capitate, hard, apex breaking up and 

 becoming powdery; asci cylindrical, 8-spored; spores glo- 

 bose, coloured. 



Growing on the roots of plants underground. The fungus 

 resembles a miniature drum-stick in appearance, being about 

 3-4 mm. in height. 



Vine root fungus. According to Prillieux serious injury is 

 done to vine roots by a minute subterranean fungus called 

 Roesleria hypogaea (Thiim. and Passer.). I have found the 

 fungus on dead rose-tree roots in this country. When the 

 roots are attacked the vine languishes for three or four years, 

 then dies outright. The disease spreads in the soil to 

 neighbouring plants. In many instances where the injury 

 had been attributed to Phylloxera, Armillaria mellea, or 

 Dematophora necatrix, the true cause was found to be due to 

 Roesleria, although the general symptoms were similar to 

 injury caused by the other pests enumerated. The mycelium 

 of the parasite attacks all the various tissues of the root, the 

 walls of the woody fibres being curiously corroded by the 

 action of the mycelium. 



The fruit of the fungus is only produced on absolutely 

 dead roots. It appears under the form of clusters of slender 

 stems, each bearing a small globose head, the whole resembling 

 a miniature drum-stick. The fungus is not confined to the 

 vine. I have seen it in this country on the dead roots of a 

 rose-tree. 



There is much difference of opinion as to whether this 

 fungus is in reality parasitic, or whether it is saprophyte, 

 following on the injury caused by a parasite. Hartig inclines 

 to the latter view, whereas Jolicoeur considers that he proved 

 by experiment the parasitic nature of Roesleria. 



The entire height of the fruit of the fungus is about 2 mm., 



