iI' 1' M'.
I :|
from Mildew. But though the varieties which are strictly
American do not suffer, European kinds imported into the
United States are frequently affected.
The Potato Murrain arises from a Mould of very different
affinities, w’hose spawn attacks the tissues of the plant in
every direction, being present in the tubers and stems, as well
as in the leaves. I t has a peculiar property of causing speedy
decomposition of the tissues with which it comes in contact,
and hence induces rapid—sometimes inconceivably rapid !—
decay.
The sulphur remedy is not applicable here, because the
spawn is never superficial, as in the Grape and Hop Mildew ;
nor at present do we know of anything which effectually
checks its progress, though numberless plans have been suggested.
Early planting, and destruction of the haulm as soon
as the Fungus makes its appearance, give the best prospect of
success.
The putrescence of Apples and other fruit is often promoted
by a similar cause, as first pointed out by Dr. Hassall,
who induced decay in perfectly healthy fruit by inoculation,
but never apparently without some external lesion. A multitude
of other Fungi, belonging to various genera, induce disease
in leaves, as in the Mulberry, Vine and hundreds of
other plants; but I cannot speak of these now, hut must pass
on to those species with loose dustlike fruit, which prey upon
our cereals, aud other objects of cultivation in the fields. The
diseases produced by these are known under the name of
Smut, Bunt, Mildew,* Bust, etc., and are often extremely in-
* I t ¡3 unfortunate that the word Mildew (Mehl Thau, meal dew) should he
applied to any Fungi besides the white Leaf Moulds. Its application to a particular
disease of wheat is uniTcrsally diffused, and cannot be checked, though
constantly inducing error. ,
jnrious. Some of these, as Smut and Bunt, attack the tissues
of the seeds, their floral envelopes, or the receptacle in which
the flowers grow, or, in rarer instances, the leaves and stems,
converting them into a mass of loathsome, sometimes fetid
dust; others, as Mildew and Bust, attack the leaves and
stalks more especially, forming little rusty spots or streaks,
and exhausting the plant by the growth of their spores and
spawn at its expense. Sometimes they exercise a specific
action upon the tissues, and cause the plant to assume various
thickened or distorted forms analogous to those which
are produced by the punctures of insects. Some of these, as
Bunt, admit of easy extirpation,* as the spores will not grow
when treated by various chemical substances, and, as they are
lighter than water, are in great measure removed by simply
washing the seed. The others, as far as is at present known,
admit of no remedy, though several nostrums are extensively
sold under the pretence of preventing their growth.
There remains another Fungus productive of disease in the
grains of rye, barley, wheat, and many field grasses, under
the name of Ergot. The white substance of the seed is converted
by this Fungus into a firm mass, without any appearance
of meal, and when the Ergoted grain is sown, it produces
a small species of Cordiceps (Plate 23, fig. 7), not unlike the
species which attack insects.
* Steeping the wheat in solutions of mineral salts, puddling it with^ quicklime
stirred up in boiling water, and plain washing with water or brine, are
amongst the means employed. The most efficacious, perhaps, is one used in
France—viz. steeping the grain in a strong solution o f Glauber’s salt (sulphate
o f soda), and then dusting it with quicklime, the effect of which is to coat
the seeds with sulphate o f lime or gypsum, and to set free caustic soda for the
destruction of tho Bunt spores. Where solutions are used, the Bunted- grains
which have not been broken in threshing are skimmed off, and it is probable
from the other practices, where tho contents of the unbroken Bunts can scarcely
be affected, that those spores o f the Bunt only are injurious which are scattered
over the Wheat.