348 Blindness in Barley and Oats. [sept., 



The symptoms of its presence are as follows : — The young 

 leaves and leaf- sheaths are at first marked with minute, scat- 

 tered, pale green spots ; these spots increase in number and size, 

 and the leaf gradually changes to a sickly yellow-green colour, 

 after which it droops and ceases to grow. Finally the spots 

 become darker in colour, and have an olive green tinge. In 



Fig. l. — Hyphre of Barley " Stripe" Fig. 2. — Spores of Barley 



fungus: Helminthosporiam " Stripe " fungus. 



graminewn, Rabh. (x 550.) (x 55°-) 



some instances, when the fungus is very abundant, the leaf- 

 sheaths and leaves are of a uniform brownish-olive colour. 

 The stunting of the plant is in proportion to the severity of the 

 •attack, but in almost all instances the plant is practically killed 

 before the ear is liberated from the leaf-sheath enclosing it, 

 hence the disease is known as " blindness." 



The fungus has been observed this season on the leaves of 

 wild barley (Hordeum miirinunt) in the neighbourhood of Kew. 



Ravn, a Danish botanist, has recently studied the disease, 

 and has also shown that oats are subject to an exactly similar 

 disease, caused by a fungus very closely allied to the barley 

 Helm inthosporiu m . 



The fungus is difficult to eradicate ; two different kinds of 

 spores are produced, and these on germination are capable of 

 growing on decaying vegetable matter, and thus keep them- 

 selves going on the land until a crop of barley is again sown. 



In addition, minute sclerotia or condensed masses of 

 mycelium are formed in the leaves, and these bodies retain 

 their vitality for a considerable period of time, and are not likely 

 to be injured by passing through the intestines of an animal, 

 and may thus be returned to the land with manure. 



