RYE SMUT 221 



TiUetia decipiens, Winter = Tilktia secalis, Kiihri. — 

 Spore-mass blackish-brown, formed in the ovary in rye, 

 also in several wild grasses. The Agrostis pumila of 

 Linnaeus is nothing more than Agrostis vulgaris dwarfed 

 by this Tilktia. 



RYE SMUT 



{Urocystis occulta, Rabenh.) 



This smut is most abundant on rye, but also occurs less 

 frequently on oats and barley, and has been met with on 

 wheat in Australia, according to Wolff. 



It forms long grey lines on the leaf-sheaths, leaves, and 

 upper part of the culm. When the epidermis, which for 

 some time covers the spores, is ruptured, the streaks are 

 black and powdery. In diseased plants the tissues are 

 more or less destroyed and deformed, the ear is arrested in 

 its development, and the culm often bends over at the 

 point attacked. 



The spores are in small clusters, two to three central 

 ones, thick-walled, dark-coloured, and fertile, surrounded by 

 several pale, sterile cells. On germination a germ-tube is 

 formed, which bears at its tip a whorl of cylindrical, 

 secondary spores, each of which on germination gives origin 

 to a slender germ-tube from its basal end. These germ- 

 tubes inoculate the host-plant by penetrating its tissues 

 when in the youngest condition, soon after sprouting. 

 Inoculation cannot be effected at a later stage of growth 

 of the host. 



Preventive Means. — Jensen considers that this smut 



