DISEASES OF CULTIVATED PLANTS. 455 
Loose Smut. This is a smut fungus (Us¢ilago 
Tritict Jensen) which converts grain and glumes 
into a sooty mass of spores. These heads of 
loose smut are most obvious at the blossoming of 
the wheat. The disease is worse on certain 
varieties of wheat. It may be prevented by the 
modified hot water treatment as per calendar. 
Rust. While essentially the same to the 
ordinary observer, the wheat rust is produced by 
two rust fungi (Puccinia graminis Pers. & P. 
rubigo-vera DC). Only the last named passes the 
winter in the wheat plant. Both have the light 
red and the black (dark) stages and are very 
damaging under conditions which favor the rust. 
In Europe, Australia, and California wheat 
growers hope to select rust proof varieties of 
wheat. Recently in England quite an impetus 
has been given to wheat breeding by the work of 
Biffen upon resistant varieties of wheat. This 
resistance applies inthe English studies not only 
to rust, but to some other features. The matter of 
resistance is the hope of rust prevention. (See 
Bulletin 97.) 
Stinking Smut of wheat is caused by a still 
more destructive smut fungus, (7Zilletia foetens 
B & C) which converts the kernels of wheat into 
dirty, stinking mass- 
es of spores. These, 
if abundant, ruin the 
with the seed grain. 
of wheat. 
See Pine. 
Fig. 106. Diseased and sound 
spike of Poole wheat. In the one 
atthe left the kernels have been 
destroyed by Stinking smnt and 
spikelets are spread abruptly. 
Fig. 105. Heavy spike of 
bearded wheat destroyed by 
loose smut. These smut 
spores are scattered and find 
entrance into the forming 
kernels of wheat when the 
blooms open fer pc'tination. 
flour and render the wheat valueless for human 
food. At times 40 percent of the wheat is thus 
destroyed and the losses from it are often very 
large. Recent investigations have established 
that this smut is caused by the smut spores sown 
x ai If the smutty seed wheat is 
treated with a fungicide, such as bluestone, hot 
water, formalin, etc., 
spores without injury to the grain and the treated 
seed is then prevented from subsequent infection, 
dried and sown, a clean crop may be grown from 
smutted seed. For details of treatment see calen- 
dar and Bulletin 97, which treats of the diseases 
which will destroy these 
WHITE PINE 
