244 



DISEASES OF CULTIVATED PLANTS 



Pleospora gummipara, Oud. (=Coryneum gummiparium, 

 Oud.), is considered by Oudemans to cause the production of 

 Arabian and Senegal gum, on species of Acacia. The cause 

 of gumming on some species of Acacia has, however, been 

 proved to be due to a bacterium, and is described on another 

 page. 



Oudemans, Hedwigia, 1883, pp. 131 and 161. 



CUCURBITAEIA (GRAY) 

 Perithecia clustered on a stroma, globose, black; asci 



FIG. 70. Cucurbitaria laburni. i, branches 

 showing the fungus ; 2, stroma in section, with 

 perithecia ; 3, ascus containing spores ; 4, free 

 spores. Fig. i nat. size ; remainder highly mag. 



cylindrical, 8-spored, spores elongated, muriform, coloured ; 

 paraphyses numerous. 



Silver fir canker. Dr. Cavara has described in detail a 

 disease of Abies pectinata caused by Cucurbitaria pithy op hila 

 (De Not., var. cembrae, Rehm.). Trees are attacked up to 

 the age of sixty years, but younger trees are most susceptible. 



