The farmer and mechanic. [volume] (Raleigh, N.C.) 18??-19??, 1902-11-04

part of it's juices. Thus we have two
plants growing together for their mutual
benefit. In this case the farmer gets
the lions Share of the profit for he gets
the plant with all it's stores of nitrogen
compounds, the result of bacterial action
Inc second paper was read by Cadet
j. G. Beavers, Of Wake, who treated Of:
RCSTS ON THE CEREALS.
Rusts are widely distributed over the
world wherever cereals are grown.
The amount of damage done by rusts
can hardly be estimated, but Mr. Mark
Alfred Carlton, Assistant in the Division
of Vegetable Physiology ard Pathology.
says that the annual grain loss from
rusts in the United States far exceeds
the loss from any other enemy insect,
or fungus, and often equals those from
other causes combined.
There are several hundred different
kinds OF rusts, many of them on weeds
or other eunimportant plants, but l shall
describe only one or two of them.
Wheat rust makes its first appearance
| in early summer, causing dark red spots
| to form on the leaves, either in the up
| per or lower surfaces. These red spots
| contain the spores, which are parts espe-
| cially organized to reproduce the rust.
| Here is diagram of a spore of the
wheat rust, greatly enlarged. You see
| that it is round and has a rough sur
| face. The wheat rust is really caused BY
very small lowly organized plant
| which grows within the tissues of the
| leaf and sends to the surface of the leaf
| numerous stalks, as shown in the da-
! gram. Eeach of these stalks bears al its
| tip reddish spore like this. The spore
| is to the rust what a seed is to an ord-
| nary plant, i. e., it serves to reproduce
| the rust. AS these spores occur in great
numbers they form the rusty looking
/ lines and spots, like these, which give
name to the disease. These spores are SO
small that it would take 25,000 placed
end to end to make an inch. These
| spores ripen in ten or fifteen days from
the time the injecting spores fall upon
the plant. After these spores ripen they
are loose and are easily carried by the
wind to uninfected plants where they
alight until sufficient moisture is afford
| ed for termination. Then the spore
sends out a tube, which enters the It's
sues of the leaf through a small opening
| the breathing pore OF the plant, as you
see in this diagram. Here the rust de-
velcps, producing more spore estalks
which again bear at the tip more spores
| These spores are carried, as before by
the wind to new hosts. Thus you sec
! rapidly the disease spreads.
1t was once thought that this complet.
ed the life cycle Of the rust, but more
| recently it has been found that this is
only one stage stage now called the
summer stage" and the spores the
summer spores" Toward the end OF
summer this same rust develops spore
| stalks which bear entirely different
spores from the round thin walled spore
These spores are like these shown in thi:
diagram two-celled with thick heaV.
wall around them. This is called The
Black Rust or winter spore, and appear:
on the wheat stubble after the wheat !:
harvested, and of course does the tarine
i no present damage. These black spores
are the ''resting spores" which lie owe
winter and are scattered by the wind
Many of them are carried to the par
berry leaves in spring. They there ger
inmate and enter the tissues of tn
leaves, developing a mycelium, whici
| produces spores, not as before, but in
cup on the under surface Of the leaf, a.
shown in this diagram. These spore
ripen and are carried by the wind to tn
growing wheat, where the disease again
becomes parasitic on the wheat, CAUSING
much damage to the farmer. It Woul
be we'll to mention one fact here, namely
that any one OF these stages can .
omitted by the rust. The stage on tn
} barberry is often omitted and the Wlnte
! spores are carried directly from the
; wheat stubble to the growing wheat II
the spring.
1t is impossible for any kind OF rus
| to make appearance on wheat or an
| other plant in any kind of weather un
less the spores of the rust are present
The disease is not caused by wet Weath
| err as many farmers think, but more OF
ten appears in wet weather because tn
! presence of moisture is necessary for tn
| eermination of the spores. | have eX
amined the spores of several rusts unde
! miscroscope and found those of corn rus
, to be like those shown in this diagram
, | also planted some of these spores II
: water to see if they would eermlnate.
, took some spores from growing and pu
, them on some young corn plants III IN
, hot house and covered them with a we