It stands to reason that were our summers warmer we should be able to
grow grapes successfully on open walls; it is therefore probable that
a new grape bag, the invention of M. Pelletier, 20 Rue de la Banque,
Paris, intended to serve a double purpose, viz., protecting the fruit
and hastening its maturity, will, when it becomes known, be welcomed in
this country. It consists of a square of curved glass so fixed to
the bag that the sun's rays are concentrated upon the fruit, thereby
rendering its ripening more certain in addition to improving its quality
generally. The glass is affixed to the bag by means of a light iron wire
support. It covers that portion of it next the sun, so that it increases
the amount of light and warms the grapes without scorching them, a
result due to the convexity of the glass and the layer of air between it
and the bag. M. Pelletier had the idea of rendering these bags cheaper
by employing plain squares instead of curved ones, but the advantage
thus obtained was more than counterbalanced by their comparative
inefficacy. In practice it was found that the curved squares gave an
average of 7° more than the straight ones, while there was a difference
of 10° when the bags alone were used, thus plainly demonstrating the
practical value of the invention.
Whether these glass-fronted bags would have much value in the case of
grapes grown under glass in the ordinary way is a question that can only
be determined by actual experiment; but where the vines are on walls,
either under glass screens or in the open air, so that the bunches feel
the full force of the sun's rays, there can be no doubt as to their
utility, and it is probable that by their aid many of the continental
varieties which we do not now attempt to grow in the open, and which are
scarcely worthy of a place under glass, might be well ripened. At
any rate we ought to give anything a fair trial which may serve to
neutralize, if only in a slight degree, the uncertainty of our summers.
As it is, we have only about two varieties of grapes, and these not the
best of the hardy kinds, as regards flavor and appearance, that ripen
out of doors, and even these do not always succeed. We know next to
nothing of the many really well-flavored kinds which are so much
appreciated in many parts of the Continent. The fact is, our outdoor
culture of grapes offers a striking contrast to that practiced under
glass, and although our comparatively sunless and moist climate affords
some excuse for our shortcomings in this respect, there is no valid
reason for the utter want of good culture which is to be observed in a
general way.
[Illustration: GRAPE BAG.--OPEN.]
Given intelligent training, constant care in stopping the laterals, and
checking mildew as well as thinning the berries, allowing each bunch to
get the full benefit of sun and air, and I believe good eatable grapes
would often be obtained even in summers marked by a low average
temperature.
[Illustration: GRAPE BAG.--CLOSED.]
If, moreover, to a good system of culture we add some such mechanical
contrivance as that under notice whereby the bunches enjoy an average
warmth some 10° higher than they otherwise would do, we not only insure
the grapes coming to perfection in favored districts, but outdoor
culture might probably be practiced in higher latitudes than is now
practicable.
[Illustration: CURVED GLASS FOR FRONT OF BAG.]
The improved grape bag would also offer great facilities for destroying
mildew or guarantee the grapes against its attacks, as a light dusting
administered as soon as the berries were fairly formed would suffice for
the season, as owing to the glass protecting the berries from driving
rains, which often accompany south or south-west winds in summer and
autumn, the sulphur would not be washed off.
[Illustration: CURVED GLASS FIXED ON BAG.]
The inventor claims, and we should say with just reason, that these
glass fronted bags would be found equally serviceable for the ripening
of pears and other choice fruits, and with a view to their being
employed for such a purpose, he has had them made of varying sizes and
shapes. In conclusion, it may be observed that, in addition to advancing
the maturity of the fruits to which they are applied, they also serve to
preserve them from falling to the ground when ripe.--J. COBNHILL, _in
the Garden_.
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