St. Tammany farmer. [volume] (Covington, La.) 1874-current, 1884-02-16
Wheat Rust,

= 10 begin at the beginning: rust
whether on wheat, oats, barley or any
other cereal. is \ parasitic plant of very
simple structure, but rather compley
habits. When we use the term s.plant''
IN this connection it must be understood
as having the same meaning rs when it
Is rs, applied 10 ordinary vegetation.
wheat rust is as much plant as an
OAK tree is. The two stand we'll 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
nourlshment from the water and the
earth. the rust-plant has none of these.
Think OF a 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 grow? 1t does iust
what we might expect it to do. 1t
steals its food from plants which have
leaves and roots. 1t is thief, or as we
say in botany. it is a parasite. Simple
as a 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 common hand-lens these
patches are seen 10 be made of many
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
alighting upon the leaves of wheat:
here they germinate. and soon penetrate
the skin of the leaf, an! begin a 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
on grain. Every red-rust
spore may produce more red-r,lst. di-
rectly, by falling upon leaf and ger
there. In this manner a small
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- |
me- red rust However. these black |
spores are SO tough skinned that they
endure the W inter-, and the next spring
terminate in great numbers. They
irst grow a little thread like stalk, and |
IN this are produced several excessively
small spores, known as sporidia. These
asst. on account of their minuteness, are
widely dispersed by the winds, and
ome. falling upon barberry leaves,
terminate here, and thus start the bar
'erry cluster cup. The complete round
# life is as follows: Q the cluster
up on the barberry, (2) the red rust
n the wheat, 60 the black rust on the
wheat, (4) the termination of the black
ust spores, forming sporidia, which in
urn then produce No. again. Until
ecently no variation from this round of
fe was known, but last year Mr. Plow-
light, an English investigator. made
he important discovery that the sporid-
la, which can not affect cd leaves, are
be to terminate upon, and enter into,
he very young leaves of the wheat.
When they do this they produce direct
the red rust stage, the cluster-cup
tage being omitted.
Now let us consider the significance
this. If wheat grains are germinat-
lg at the same time that the sporidia
re produced, the young wheat plants
ecome inoculated with the parasite
inter wheat terminates in the fall,
lille the sporidia are produced in the |
BRING; there is here no danger then.
ut it is far different with spring wheat, :
h oh terminates at the exact time the
,Oridia are forming. Here, then, is the
IplanatiOn of the fact that rust is COM
ION in some regions where the barber s
: is not grown; it is simply that the
uster-cup stage is omitted, because of {
e fact that the sporidia are able to in !
'ulate the leaves of the young spring '
heat plant. There is not space for q {
rther discussion of this matter now, 5
1t one suggestion may be made, and t
at is that it is very clear that straw
hich has black rust upon it is not good s
ing to have scattered around upon the Q
rm in early spring. Last spring t
und the black spores producing myr. v
DIS of sporidia upon straw which had S
EN- used for the winter protection Of s
Such straw is much more q
vigorous than an equal amount Of
lnada thistle stems filled with their !