The herald-advance. (Milbank, S.D.) 1890-1922, 1904-09-16

South Dakota Experiment
Station
press Bulletin No. u

press Bulletin No. ~
The season of 1904 has been an es-
pecially disasterous one for the wheat
crop of South Dakota and neighboring
states. The season, which opened
very favorably for the growth of wheat
and other small grains, promising fair
returns, ended disasterously through
the ravages of the rust. Everyone
should be interested directly or indi-
rectly in any subject concerning the
production and manufacture OF wheat,
q staple product. The inquiries which
have come to the Experiment Station
concerning the many phases OF the
rust problem show this to be true.
THE newspapers and agricultural pa
pers have published varied accounts OF
the rust, some of which have been
wholly or in part correct, while others
have been absolutely false. Many facts
in regard to the life history of rusts in
general are we'll known to scientists.
Many others are, however, dOubtfully
understood, and these profile MS still
remain to be solved. The object of this
bulletin is not to present any absolute
ly new facts to the public, but to pre-
sent in brief those facts which have
been known for some time, and others
which have been secured by investi-
gators during the past few years OF
research.
The one question which must be
cleared up in the minds of everyone is
that rusts, SHUTS, mildews, and, in fact,
nearly all plant diseases, are caused
by small parasitic plants living de-
pendent upon other plants for their
existence. The powdery mildews per-
haps exhibit this dependence of one
plant upon another more clearly than
rusts or smuts. In the powdery mil
dews, an example of which is the very
common mildew occurring upon the
cultivated lilac, the parasite lives
upon the surface of the leaves and
stems and other parts of the plant. A
near examination of the ares whitened
by the mildew shows that it consists
of a network of very fine threads at
tached to the surface of the host plant.
This network of threads is the plant
body of the mildew, and feeds upon
the host plant, which is the lilac in
this case, by means Of small sucker
like organs which project into the leaf
or stem and extract the sap. Late in
the season small black bodies usually
appear upon this white mass of
threads. These bodies contain several
smaller bodies, which serve to repro
duce the plant. These reproductive
bodies are called spores.
The smuts and rusts are plants SINH
lar to the mildews, but develop their
mass of threads, forming their plant
body inside of the host plant, instead
of upon the surface, as is the case with
the mildews. The spores of some
smuts, such as wheat smut, terminate
upon the grain of wheat, and the
threads which result from this ger
mination penetrate the young wheat
plant and live within the tissues of
the wheat plant throughout its period
of growth. When the grains begin to
fill out the smut plant, living as a
mass of threads within the wheat
plant. forms its spores within the
wheat grain. This grain, filled with
black spores, is a well known object
t. wheat growers, and is the main evil
dence ina smut is present in the
wheat.
With trusts the life histories are
very much more complicated. There
are many species of rust growing upon
all of our cultivated grains, grasses
and many of our weeds, trees and
OUllc CQltlF dtCu plduuo' Ivy u vi
dinarly called rusts because certain
stages resemble in color the rust of
iron. This is as far as they are con-
nected in any way with the rustS of
metal. The rusts of wheat are those
in which the greatest interest is taken
at present, and are the ones which it
is my purpose to describe here
briefly. There are several kinds of
wheat rusts existing in the United
States today. The exact number of
species is doubtful. There are prob
ably, however, at least three. The one
which seems to have caused the great
est losses to the wheat crop of the
Northwest is the black stem rust of
wheat. All the species of wheat rust
live alternately upon different host
plants. The black stem rust is SUP
posed to pass through one stage upon
the wheat, the next upon the Burberry,
and then back to the wheat again.
Another species a~lternates between
the wheat and members of the buck
thorn family. Still another species
agrig ates between the wheat and
the members of the borage family.
All of these species Or kinds of
rusts are better known upon the
wheat plant than they are upon the
other host plants, and many facts
still remain to be discovered as to the
relations between the various kinds of
wheat rusts and their other hosts. 1t
is probable that there are other plants
upon which wheat rusts occur of which
we have no accurate knowledge.
\ The black stem rust of wheat may
be discovered early in the season upon
the stems of the wheat and exhibits
itself as red lines upon the surface of
the wheat plant. These red lines are
formed by the breaking of the cover
ing of the leaf or stem and the forcing
out of red spores Or reproductive
bodies of the rust plant which is liv-
ing within the wheat plant. This
stage is commonly called the red rust.
The red GUST spores, or summer spores, |
may 0e scattered by the wind from one
wheat plant to another, or to thou
sands of other wheat plants. They
lodge upon the leaves and stems of the
wheat and under favorable conditions
of heat and moisture they terminate
there, forming new threads which en-
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