Green-Mountain freeman. [volume] (Montpelier, Vt.) 1844-1884, 1879-07-16
Che frfeman.
LETTERS on NATURAL HISTORY.
No. s.
TX Dr.. HIRAM A. CUTTING.
Fungi and AnimalculeS.
MILDEW OR RUST.


Jaw,n but mildew" is one of those
Io,se terms that represents no definite
ilra. or 4 very different one to various in
dviuals.
Talk of mildew of grain to a farmer,
and he tells you of the rust which appears
in lines or irregular spots upon the wheat
stalk, indicating Pucci,sia granlipis, which
Is known to hun and generations before
him in many sections as mildew.
Talk 10 Il New England housewife OF
midew, and she will describe minute spe
cies of fungus which attacks damp linen,
a, true midew, and will ask if you know
what will remove the spots occasioned by
it.
Ask the hop grower Of New York about
mldew. and he will point out Il species OF
mould tn 1t infeSls the hop vine, but which |
differs us much from the mildew of th'' |
south as does the milew of linen. The |
librarian will tell you of mil LEVIED books
and papers, and the housemaid OF mil |
dewed cellars,-al meaning u fungu- |
Growth, but us wide in their Significance |
as the poison hemlock and hemlock tree,
Mildew in England means in llteratur"
but one thing, and that is the rust up Il
wheat and other grain, known scieniilical-
" us Puccinja graminis.
Bnt let US look into the history of thl- |
pest. In view of Il clearer understanding
Of this peculiar pest, so long supposed to
be several sep ptrate species, and which
under the present light of science seems
fast merging into one. We will suppose
a fine day in June dawns upon our re
solve to learn of midew, or rust, and W.
stray away from the village to gain the
chance to examine a wheat field. Having
reached the field, there is no appearance
of anything but healthy crop; we walk
into il perhaps fifteen or twenty yards be-
fore we find single fungus of which we
are in quest. But let us look closely down
at the green leaves at the very bottom OF
the wheat plant and we are soon reward
ed, Us we shall find one or two that look
rusty. The surface seems powdered with
red ochre, and to have grown sickly under
the operation Pluck it carefully. and eX
anime it with a low magnifying power; II
pocket lens will do. Already the cuticle
of the leaf is traversed with numerous
Longitudinal cracks or tiSsures, within
which and around which you discern an
orange powder, to which the rusty appear
ancc on the leaf is due. Farther eX uni
n,,ion reveals also portions in which the
cuticle is distended into yelowiSh elong,
ted plstules. not yet ruptured, and which
is an earlier stage of this same disease.
This is the rust of the New Englang agri-
culturist the IrichodaSts ruJigO-uera OF
the botlnist, or the fist phase of mildew.
To know more Of this parasite we mus'
tlke 1t to our microscope, and by careful
manipull ion we sh Ill fad that the vege
talive system of tn S, rs well rs OF all
similar lungi consists of number O
delicate simple or branched threads, Otter
inlertwining and even uniting one to the
other by little branchie cts. These threads
rs we have before explained are called The
mycelium; they penetrate the intercelulal
spaces and iusinuate TIL m selves in com
pete network am ny the cells of whicl
the leaf or OF ler deceased portion Of the
plant is composed. We my regard the
whole myceiiun Of one puStule, or por
spot, US the vegetative system of one fun
gal plant At first 1t might have originate
as several individuals, which aflerwar'
become combined US one, for the produc
ton of fruit, and bv their combined effur
a cluster of fruit or spore spot, is pro
duced.
In the first instance number of minute
transparent, co orless ccllules are deveI
oped from the mycleum; these enlarg
aad are filled with AN orange colore
cndochrome, and appear beneath the lei
as yellowish epots. As consequence
this increase of bulk, the cutiole become
d,tenled in the form of Il pustule over Il
yellow celules, and ut length, unable
withstand the pressure from bencat
ruptures in irregular, but more or le
elongated tissures, and the yellow bodie
which will call spores, break from the
short pedcels and escape; TO the make
eye presenting the appearance of :
orange powder.
On the first of August we will aga
visit our wheat field. Rusty leaves a
more common than before. A little car
full examination, and here and there
shall find leaf with decidedly brow
nustules intermixed with the rusty ont
If we remove from the browner spots
little f the powder by means of Il sha
pointed knife and place it in drop of "
ter, and cover it with thin glass, al
place it under our microscope, a diflert
series of forms will be observed. The
will still be portion Of one-celled yelc
spores, but the majority will be elongat,
mostly with short stalks, and either ,
cidedly two-cel!ed or a tendency to be
These two-celled spores are anoth
form of the midew called P~ccinia gra
tnis, which may be produced in the Sal
pustules and from the same mycelium
the rust previously described, and is g,
orally considered at the present time to
the same fungus Other grain and v;
Gus other plants are likewise affected
FIG .. Fig, 3 represents
s s q, wheat straw inft
& ed with this rust !;
cluster of spores M
nifed; c, single sp
magnified 800 diai
81 ri zl{sf ters.
= - This rust is so &C
\. s. "A & mon and so much al
on all plants that
g3l Ie2 plate will answer
represent the fun
,l,.,