52 
Coi^ORADO Experiment Station 
Loose Smut (Ustilago tritici) — Loose smut of wheat 
is identical in all respects to loose smut of barley 
described above with the exception that it can affect 
only wheat, while the loose smut of barley can affect 
only liarley. The hot water treatment only will control 
loose smut. 
Flag Smut (Urocystis tritici) (53)— A flag smut of 
Avheat very similar to flag smut of rye has recently been 
discovered in this country. Previous to this it was 
known to occur only in Australia, Japan and India. It 
has been found in the United States only in one place, 
namely, Madison county, Illinois. 
The government has established strict quarantines 
in an effort to prevent the further spread of the disease 
and the strongest efforts are being made to completely 
eradicate it. Seed treatment combined with crop rota- 
tion as recommended for flag smut of rye should ef- 
fectively control flag smut of wheat. All seed wheat 
should be treated before planting as a precaution in 
preventing its introduction into new areas. Should flag 
smut of wheat be discovered in Colorado it should be immediately 
reported to the Agricultural College. 
RUSTS 
The rusts of cereals are too well known to require much descrip- 
tion. In destructiveness they rank second only to the smuts. In 
some years the loss even exceeds that caused by the smuts. In 1916 
it is estimated that the black stem rust alone destroyed at least 
280,000,000 bushels of wheat in Canada and the United States. To 
this must be added the loss of oats, barley, and rye, which ranged 
from 15 to 25 percent of the crop. 
The rusts occur not only on the cultivated cereals but many 
species of wild grass are also affected. Certain rusts may live also 
on such plants as the barberry or buckthorn which makes them 
much harder to control. Each cereal has it own particular lUst 
which will attack no other cereal, but which may affect a number 
of wild grasses. Each kind of grass may also be attacked by two 
or three different kinds of rust. 
The cereal rusts may be roughly classified into twm groups, 
namely, the leaf rusts that are more commonly found on the leaves 
and the stem rusts of those found on l)oth stems and leaves. It is 
the latter group thai is responsible for the greatest loss. 
