404 DISEASES OF CULTIVATED PLANTS 



Hirneola auricula-judae (Berk.), commonly known as 

 Jews' ear fungus, is parasitic on the elder. It has also been 

 recorded as occurring on elm. Prillieux and Delacroix state 

 that it is a wound-parasite, attacking the mulberry in France. 



Irregularly human ear-shaped, pliant like thin india-rubber 

 when moist, rigid when dry. Externally with delicate greyish- 

 white silky down, sessile, clustered, 4-7 cm. across. Spores 

 reniform, 20-25 x 7~9 / u - 



Of no importance as a parasite. Grows on elder, which 

 it is said to kill. 



Hirneola polytrichna (Mont.), an allied species, is not a 

 native in this country, but is sometimes met with on imported 

 wood. It is a source of revenue in New Zealand, being 

 exported to China as an article of food, where it is considered 

 as a delicacy. 



HELICOBASIDIUM (PAT.) 



Resupinate, incrusting, soft, basidia straight when yo.ung, 

 then curved, transversely septate, bearing a spore from each 

 cell of the basidium ; spores hyaline, i-celled. 



Mulberry root rot. According to Tanaka the mulberry- 

 tree, which is cultivated on a large scale in Japan for rearing 

 silkworms, is subject to a very serious disease caused by a 

 fungus called Helicobasidium mompa (Tanaka). The root is 

 first attacked, and when the fungus is established its presence 

 is indicated by the growth of the shoots being arrested, the 

 small size of the leaves, and their wilting and finally dying. 

 The shoots also die later in the season. The lowest roots 

 are the first to succumb, the tree endeavouring to reinstate 

 itself by the formation of others higher up, these in turn are 

 attacked, and the tree is usually killed in about three years. 

 The diseased roots are felted over with a network of mycelial 

 strands of a purplish-brown colour, some of which spread in 

 the soil. When the fungus is well established on the root it 

 emerges above ground, it gradually ascends the trunk and 

 lower branches, which become covered with a thin felt of 

 dark brown mycelium having a paler, growing margin. Eventu- 

 ally certain portions of the fungus spread out at right angles 

 to the substratum. The hymenium, which is of a whitish 

 colour, is produced on the free portions. Numerous sclerotia 

 are found in the decaying roots. 



