rvest-time.

"Since this disease is caused by an internal parasite, it is natural to
expect certain responses to its presence. It should be noted first that
the smut fungus is living at the expense of its host plant, the wheat,
and its effect on the host may be summarized as follows: The consumption
of food, the destruction of food in the sporulating process, and the
stimulating or retarding effect on normal physiological processes.

"Badly smutted plants remain in many cases under-size and produce fewer
and smaller heads. In the Fife and Bluestem varieties the infected heads
previous to maturity exhibit a darker green color, and remain green
longer than the normal heads. In some varieties the infected heads stand
erect, when normal ones begin to droop as a result of the increasing
weight of the ripening grain.

"A crop may become infected with smut in a number of different ways.
Smut was originally introduced with the seed, and many farmers are still
planting it every season with their seed wheat. Wheat taken from a
smutty crop will have countless numbers of loose spores adhering to the
grains, also a certain number of unbroken smut balls. These are always a
source of danger, even when the seed is treated with fungicides before
sowing.

"There are also chances for the infection of a crop if absolutely
smut-free seed is employed. First, soil infection from a previous smutty
crop; second, soil infection from wind-blown spores. Experiments have
shown that separated spores from crushed smut balls lose their effective
power in from two to three months, provided the soil is moist and loose,
and in no case do they survive a winter.

"It does not seem probable that wheat smut will be controlled by any
single practice, but rather by the combined use of various methods: crop
rotation; the use of clean seed; seed treatment with fungicides;
cultural practices and breeding; and selection of varieties.

"Failure to practise crop rotation is undoubtedly one of the main
explanations for the general prevalence of smut in the wheat-fields of
eastern Washington. Even with an intervening summer fallow, the smut
from a previous crop may be a source of infection. Experience shows that
a fall stubble crop is less liable to smut infection than a crop
following summer fallow. The apparent explanation for this condition is
the fact that the summer fallow becomes infected with wind-blown spores,
while in a stubble crop the wind-blown spore