244 



DISEASES OF CULTIVATED PLANTS 



Pleospora gummipara, Oud. (=Corvnei/m 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, Hedivigia, 1883, pp. 131 and 161. 



CUCURBITARIA (Gray) 

 Perithecia clustered on a stroma, globose, black ; asci 



-J? 



$mm*x 





Fig. 7" Cucurbitaria laburni. i, bram 

 showing the fungus; 2, stroma m section, with 

 perithecia ; 3, ascus containing 

 spores. Fig. 1 nal sia . 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 pithyophila 



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

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



