118 



which conjugate in pairs. Infection threads are either produced by these 

 sporidia capable of penetrating the host plant or, as is usually the case, 

 secondary sickle-shaped sporidia are borne on short filaments and these 

 sporidia produce infection threads. The formation of sporidia greatly in- 

 creases the chances of the fungus to infect the host. 



The infection of the wheat plant takes place soon after the germina- 

 tion of the grain and even before the first leaves are put forth. Hoffman 

 believed that the infection threads can enter only the sheathing primary 

 leaf or the collar between the root and stem while they are yet very young 

 and delicate and concludes that anything which would hasten the growth 

 of the young plant would tend to lessen the chances of infection. 1 Bolley 

 believes that infection does not take place unless there is a large num- 

 ber of sporidia in close contact with the seedling during the infection 

 period.- The mycelium after gaining entrance to the young plant pushes 

 its way upward with the growth of the host, the older mycelium dying and 

 its contents passing upward into the young advancing ends, and finally 

 fruits in the ovaries by the production of ehlamydospores from sporogenous 

 hyphae that have developed abundantly in them. The Stinking Smut 

 differs from the Loose Smut of Wheat in that the destruction is entirely 

 confined to the ovary contents. The ovary coat is left intact, so that one 

 would easily fail to recognize any infection unless he made particular ob- 

 servation or noticed the disagreeable odor characteristic of the fungus. 

 The affected kernels are somewhat larger than healthy ones and this in- 

 crease in size causes the florets to spread, making the head more open 

 than a healthy one. When the kernels are cut open they are found to 

 be filled with a mass of olive-brown spores of a greasy character. 



The Loose Smut of Oats. 

 Vstilago avenue (Pers.) Jens, and 



The Hidden Smut of Oats 

 Vstilago lev is (Kell. & Sw.) Magnus on Arena sativa. 

 There are two distinctive species of oat smut called respectively the 

 Loose and the Hidden Smut of Oats. Both are much alike in their methods 

 of development and both succumb to the same method of treatment. Vs- 

 tilago avenae is by far the commoner and is the one which causes the 



1. Note from Kellernian and Swingle, Report on the Loose Smut of Cereals. 2d 

 Ann. Rept. Kan. Exp Sta. 1889. pp. 213-238. 



2. Bolley, H. L., New Studies upon the Smuts of Wheat, Oats and Barley N. Dak. 

 Bui. 27, 1897. 



