The Aberdeen weekly. [volume] (Aberdeen, Miss.) 1878-1933, 1884-01-25
Wheat Rust.


whether on wheat, oats, barley or any
other cereal, is q parasitic plant of very
simple structure, but rather complex
habits. When we use the term "plant"
in this connection it must be understood
as having the same meaning as when it
is applied TO ordinary vegetation.
Wheat rust is as much plant as an
oak tree is. The two stand well toward
opposite extremes of the vegetable
kingdom, the first being small and
simple in makeup, while the latter is
large and wonderfully complex. More
over, while the oak tree is possessed Of
green leaves which can gather food
from the air, and roots which draw
nourishment from the water and the
earth, the rust-plant has none of these.
Think of microscopic oak tree with
neither leaves nor roots; now that is the
condition of the rust-plant.
How then can such plant get the
food wherewith to growp 1t does just
what we might expect it to do. 1t
steals its food from plants which have
leaves and roots. 1t is a thief, or as we
say in botany, it is parasite. Simple
as rust-plant is, its round life is quite
complex. Its first stage is passed on
the barberry leaf, where it may be found
in the spring forming yellow patches.
Under 81 e9@nm0Q8p pc N made 81 mtha GsS
beautiful little cups, hence the common
name OF this stage is "cluster-cups.
Each cup is filled with orange colored
spores. The latter soon fall out and
are blown by the winds, some finally
alghting upon the leaves of wheat;
here they terminate, and soon penetrate
the skin OF the leaf, and begin process
of rapid growth in the soft interior It's
sues. In few days if the conditions
have been favorable, masses of reddish
spores are formed by the parasite just
beneath the surface of the leaf, and
these finally break through the skin,
forming now the red-rust patches so
common on grain. Every red-rust
spore may produce more red-rust, di-
rectly, by falling upon leaf and ger
minating there. In this manner small
amount Of rust in field may, under ia
vorable conditions (high temperature
with an abundance of moisture), give
rise to enough to destroy the whole
crop.
The red rust spores appear to be in.
capable OF living through the winter, so
there are produced little later, from
the same parasite, larger black patches
of thick-walled spores. This is the
black rust stage, and is the last to APP
pear. 1t often natures after the stalk
is dead, and SO appears at first sight to
be much less harmful than the preced-
ing red rust. However, these black
spores are so tough skinned that they
endure the winter, and the next spring
terminate in great numbers. They
first grow a little thread4likc stalk, and
on this are produced several excessively
small spores, known as spordia. These
last, on account of their mnuteness, are
widely dispersed by the winds, and
some, falling upon barberry leaves,
terminate here, and thus start the bar
berry cluster cup. The complete round
of life is as follows: Q the cluster
cup on the barberry, (2) the red rIst
en- the wheat, (3) the black rust on the
wheat, (4) the termination of tie black
rust spores, forming sporidia which in
turn then produce No. aSaln. Untll
recently no variation frorl this round Of
life was known, but last year Mr.. Plow-
right, an English investigator, made
the important discovery that the sporid-
dia, which can not affect old leaves, are
able to terminate upon, and enter into,
the very young leaves of the wheat.
When they do this they produce direct
ly the red rust stage, the cluster-cup
stage being omitted.
Now let us consider the significance
of this. If wheat grains are germinat-
ing at the same time that the sporidia
are produced, the young wheat plants
become inoculated with the parasite.
Winter wheat terminates in the fall,
while the sporidia are produced in the
spring; there is here no danger then.
But it is far different with spring wheat,
which terminates at the exact time the
sporidia are forming. Here, then, is the
explanation of the fact that rust is COM
mon in some regions where the barber
ry is not grown; it is simply that the
stage is omitted, because of
the fact that the sporidia are able to in
oculate the leaves of the young spring
wheat plant. There is not space for
further discussion of this matter now,
but one suggestion may be made, and
that is that It is very clear that straw
which has black rust upon it is not a good
thing TO have scattered around upon the
arm in early spring. Last spring l
found the black spores producing myr-
ads of sporidia upon straw which had
oeen used for the winter protection OF
strawberries. Such straw is much more
dangerous than an equal amount OF
Canada thistle stems filed with their
c. e. Rssssu,