210 DISEASES OF CULTIVATED PLANTS 



asci 8-spored, paraphyses slender; spores hyaline, i -septate, 



Noack, F., Zeitschr. Pflanzenkr., 10, p. 321 (1900). 

 Several other diseases of the orange-tree are described in this 

 article. 



DIAPORTHE (NiTS.) 



Perithecia membranaceous or subcoriaceous, often greyish 

 within, usually with a long, slender beak ; asci fusoid, 8-spored ; 

 spores elongated, i -septate, hyaline, with or without append- 

 ages. 



Oak canker. Oak-trees up to the age of about forty years 

 are liable to this disease, caused by Diaporthe taleola, Sacc. 

 ( = Aglaospora taleola, Tul.) The disease is indicated by the 

 presence of brown, dead patches of bark. As these patches 

 are usually of large size, and scattered all round the 

 trunk, the bark is killed, and the tree dies. Numerous black 

 stromata are formed in the dead bark, which first bear conidia 

 and afterwards the ascigerous fungus. 



Stroma formed in the bark, perithecia numerous, crowded 

 towards the centre, disc white ; asci 8-spored ; spores oblong- 

 ovate, i-septate, constricted, hyaline, with one slender 

 appendage at each end, and three hair-like appendages spring- 

 ing from the median septum, 18-24 * 7-9 /* Conidia hyaline, 

 sickle-shaped. 



Hartig suggests that when the disease appears in a wood, 

 the younger diseased trees should be felled at once. This 

 gives the remaining trees a better chance of recovery, and 

 checks further infection. 



Hartig, Forstlich-naturwiss. Zeitschr. , Jan. 1893. 



American chestnut disease. The native American chest- 

 nut (Castanea dentata) has been shown by Dr. Murrill to be 

 subject to a very serious disease caused by Diaporthe para- 

 sitica (Murr.). It was at first supposed that the tree above 

 mentioned was the only kind attacked, but it has now been 

 discovered that other species of Castanea, both native and 

 exotic, are also attacked. Infection takes place through 

 wounds, and the fungus spreads beneath the cortex in the 

 layers of inner bark and cambium, finally killing the bark, 



