The weekly Union times. [volume] (Union C.H., South Carolina) 1871-1894, 1878-08-02
NUMBER 81.
THE GRAPE MILpEWR.

of fungi Of this group of parasitic plants,
the grape-vines arc specially infested tho
two leading species of which are the Pero-
nospora viticola, or American grape vine
mildew, and Uncinula spiralis or "oidium,"
as it is commonly called. The last is close
ly related to the Oidiun, 7mckeri which has
proved so disastrous, at some seasons, to the
grape crop of European countries. The
odium is surface feeder, never eeudinx
iss threads deep tdown into thsatSsPo.s
the leaf Running here and there over
the surface of the leaves, young stems and
berries, it gives, while young, n cob
webby appearance TO the surface when
viewed with a hand lens but after forming
a multitude of pores, to the naked eye it
looks as if the surface had been finely dus-
ted with -four. This mildew makes its an.
pearance often quite early in the season,
depending upon the weather, and gradually
develops itself during the summer months.
The story Of the other midew is somc-
what different, it being confined very large
y in its action to the leaves, and develops
itself very rapidly, usually only upon the
under surface. 1t is, then, deep seated
parasite, sending its absorbing threads far
into the tissue of the foliage. TO the ma
ked eye all that one secs of this species is
usually some yellowish spots on the upper
side Of the leaves, and corresponding dis
tribution of frosty, mouldy places upon the
side. These frosty appearing spots arc due
to multitudcs Of threads, which pass through
the stomata, and branching in a trcc-likc
manner bear spore upon the extremity Of
each ultimate ramitication. These spores,
which are formed very rapily, gcrminatc in
a few hours, and thus spread the disease to
new spots on the same or another leaf. Be-
sides these aerial spores, there is another
kind found, towards tho close of the season,
within the tissue of the grape plant They
arc provided with thick coat of cclulosc
and, as they do not germiuate until spring
their special Office seems to be, to carry the
mildcw over the dormant and severe months
of winter
Though the Peronospora mildow is Pc
culiar " America, The introduced varieties
OF grape arc not exempt from its depreda-
tions. DIR. Fallow has shown that it will
grow Oh the V. vinifcra of Europe "evcn
more luxuriantly than on American grapes"
For this reason, aud also that the climate
of Europe will be especially favorable for
its fatal development, any action that would
tend 10 introduce the pest into that country
should be constantly and dstrcnuously avoided.
The collected experience of others, COM
bined with some personal observation leads
to the general conclusion that the hardy.
thick-leaved varieties-as the Concord, Ives.
and Hartford-are less affected than those
like Delaware, Iona, and Diana, which arc
spoken of as hiA.lcavcd and tender.
AS far as our limited experience goes, the
berries affected by the Peronospora show
no mould upon the surface, but turn TO n
red color early in the season, and remain
hard, sour, and of an irregular shape.
The amount Of damage done by each of
the two mildcws is difficult to decide. be-
cause they are often found growing togeth-
er upon the same vine, even on the same
leaf; but it is sufficient to say that it is
much more severe than desired This sus-
gests consideration Of remedies.
REMEDIAL MEASURES.
A mixture of six pounds of potash two
gallons Of coal tar, and one. fourth pound
carbolic acid, diluted with four barrels of
water, has been used and recommended by
some. This makes wash which is applied
to the vines. The application of flour of
sulphur, either alone or mixed with Stacked
lime, is tho leading and perhaps the most
effectual remedy. This can be best distribu
ted by means of a pair of bellows, and
should be applied even before the vines
show signs of mildew, and thereby avail
yourself of tho ounce Of preventive when
it equals pound of cure. Should the
mildew appear, the operation should be re-
peated two or three times during tho year,
or as often as good judgment will decide.
AS the winter spores of the Teronosporn
arc buried in the tissue of the leaf. and
those of tho Uncinula c!inging to their
surface, the collecting and buring of
their foliage would tend in good measure
to diminish both forms of mildew in COM
ing years. But concerted action is re-
quircd in work like this, that it may be
the most successful and for this we cannot
hope until the grape crop is on the verge
of total ruin, and doubtful if then.
AS all fungi are lovers of moisture, and
flourish only when it is quite prevalent, the
using of only those localities for vineyards
that are naturally dry, or the thorough
drainage of those that would otherwise be
wet, would do much to lessen the amount
of midew and do good to the grape, vines
in other ways than one.