1883 .] 
AMERICAN AGRICULTURIST. 
365 
Fruits.—Maturity and Ripening. 
In the botanical use of the word “fruit,” it is 
applied to the ripened ovary of the pistil, and 
whatever remains attached to it. In this sense a 
pea-pod is as properly a fruit as a peach. In the 
ordinary use of the term, we apply it to the same 
parts when they become juicy and edible. Even 
this definition must be qualified; cucumbers, 
squashes, and tomatoes are as truly fruits as are 
•apples and pears, yet we class them as “vegeta¬ 
bles.” The frequently asked conundrum, “What 
is the difference between a vegetable and a fruit ?” 
has not yet received a concise answer. The object 
of the fruit, in its natural state, is to mature and 
protect the seed, and, in many cases, when the seed 
germinates, to promote the growth of the young 
plant by decaying and affording it nourishment. 
In accomplishing these objects, many fruits ac¬ 
quire properties which make them useful to man, 
and these, by cultivation, have been greatly in¬ 
creased, and many of our cultivated fruits are, so 
to speak, monsters, in which certain parts have 
taken on a development quite unknown to the 
fruits in their wild state. Leaving out of consid¬ 
eration what are known as the “ small fruits,” let 
us glance at the changes that take place in the tree 
fruits. After the blossom drops, the young fruit 
begins to grow, and in its early state, its growth 
and its relations to the air, etc., are much the same 
as those of a leaf. In the apple and pear, one 
portion of the fruit becomes large and pulpy. 
In the peach and other stone fruits, a most remark¬ 
able change takes place. The very young peach, 
cut across, will be found to be alike all through, 
and pulpy or cellular. As it grows, one part, the 
inner of this pulpy portion, becomes greatly 
changed ; the cells, at first so soft, soon become 
lined by a material which makes them so hard, that 
we call this part of the fruit a “ stone.” This por¬ 
tion surrounds and protects the seed proper, but 
is not a part of the seed. It is a portion of the 
same part of the peach which, when ripe, becomes 
so pulpy and edible. In the almond, which 6ome 
regard as the parent of the peach, the whole ex¬ 
terior portion becomes hard and woody. In the 
apple and pear, when the fruits have made their 
growth, and can get no more from the tree, they 
prepare to sever connection with it, and, like the 
leaf, when its Work is done, are ready to fall. 
The fruit is then ripe, or rather mature, but often, 
especially the late varieties, it is hard and inedible. 
After the fruit leaves the tree, it undergoes great 
changes; these, in early apples and pears, take 
place very rapidly, often beginning while yet on 
the tree. In our autumn and winter varieties, 
these go on more slowly, and the fruit is not “in 
eating” until some weeks or months after it is 
gathered. It may be said that a fruit, after it is 
mature, at once begins to decay ; we take it at a 
certain point in its progress towards decay, and 
say that it is mellow, or in eating condition ; be¬ 
yond that it is over-ripe, the next step being rot¬ 
tenness. The physical changes, the softening, the 
juiciness, and the change in color, are well known. 
The chemical changes are not less marked. The 
fruit absorbs oxygen from the air, and gives off 
carbonic acid. In a tight fruit-room, where large 
quantities of fruit are stored, the air becomes so 
charged with carbonic acid, that a lamp will be 
extinguished, and it is not safe for one to enter 
such a room until the air has been changed by 
ventilation. The constituents of the fruits are 
greatly changed ; those which, when first picked, 
are sour and astringent, become sweet and de¬ 
licious. A marked change is in the production of 
sugar, several substances related to starch, are 
converted into sugar, some fruits containing, when 
ripe, from three to ten times the amount of sugar 
they had when green ; among other changes, tan¬ 
nic acid (the “ puckery ” principle) disappears. 
Our native persimmon affords a marked illustra¬ 
tion of the changes produced in ripening. While 
but partly ripe, its astringency is proverbial ; but 
when it has a long season, or ripening is hastened 
by frost, this completely disappears, and the fruit 
becomes very sweet and luscious. After a fruit 
has reached its best condition, it soon deteriorates 
and goes on towards decay. These changes may, 
within certain limits, be hastened or retarded by 
increasing or diminishing the temperature. Some 
green fruits, after cooking, become edible, the 
heat having caused a change in their constituents. 
The practical points to be drawn from this brief 
sketch are these: As the evolution of carbonic 
acid takes place to a great extent, large quantities 
of fruit should not be stored in the cellar of the 
dwelling house, as it will be diffused through the 
floors, and cause headaches, general lassitude, and 
other mysterious troubles. A tight fruit-room, in 
which the accumulated carbonic acid is retained, 
will greatly aid in retarding the ripening of the 
fruit, by cutting off the supply of the oxygen of 
the air. Such rooms should not be incautiously 
entered. The fruit, if gradually ripened, will be 
in greater perfection than if the process be hur¬ 
ried. The most experienced fruit-growers keep 
the room at as low a temperature as possible, with¬ 
out freezing. For home use, when fruit in the 
fruit-room is found to be nearly in eating condi¬ 
tion, its removal to a warm room, to “ finish off,” 
will be found to greatly improve its quality. Early 
apples and pears, which, if left to themselves, will 
become mellow on the tree, should be picked be¬ 
fore this takes place, whether for market or for 
home use. One soon learns when the fruit is 
mature, by the ease with which the stems part 
from the tree. Such fruit will ripen in the pack¬ 
ages in which it is sent to market. For home 
use, it may be had in the greatest perfection of 
both flavor and color, if ripened very slowly. We 
know of no better plan than to spread the fruit 
in a cool room, on a blanket, and cover it with an 
other. The fruit can be daily inspected, and those 
that are just right for eatings elected for the table. 
The Black Knot on Plum Trees. 
Mr. D. D. Gaines, uear Catskill, N. Y., brings us 
peculiarly distorted branches from his plum or¬ 
chard, and complains that the trouble is a serious 
one, as he has over two thousand plum trees more 
or less affected. The cause of this distortion of 
the smaller branches is a fungus, and it has long 
been known as “ Black Knot.” It has often been 
claimed by careless observers that the swellings 
were due to various insects which infest the peculiar 
outgrowths. The parasitic fungus attacks the 
young branches in early spring, causing them to 
increase rapidly in size ; rupture of the bark soon 
follows, and the soft substance, coming to the sur¬ 
face, expands in an irregular manner, and is shortly 
covered with a peculiar olive-green coat. The 
fungus plant is like many others of the same low 
order of vegetation, as the various moulds, mil¬ 
dews, etc., and consists of a multitude of fine 
threads, that run in all directions through the sub¬ 
stance of the plum tree. The olive color of the 
surface is due to a vast number of minute bodies 
called spores, which are formed on the tips of the 
threads, and, breaking away from their attach¬ 
ments, serve to propagate the trouble. After the 
knot has grown to some size, its soft substance 
offers a good home for various kinds of insects, 
and it is rare to find such a knot that is not thus 
Infested. This was the strong argument in favor 
of the view that the knots were of insect origin. 
The scientific name of the fungus is Sphceria nior- 
bosa , and this, the cause of the black knot, is as 
much a plant as the plum tree upon which it lives. 
The olive surface-spores continue to form 
through the summer, and at autumn another kind 
of spore begins to 
develop within the 
substance of the 
knot. These are of 
slow growth,aDdare 
not ripe until the 
following spring. 
Iu this form the life 
of the species is 
carried through the 
winter season. It 
is evident that the 
trouble cannot be 
eradicated by any 
method of trapping 
insects, or by the 
use of insecticides. 
The infesting in¬ 
sects only take ad¬ 
vantage of the soft 
substance of the 
knots, and have no 
part in their origin. 
The only remedy 
thus far known is 
the judicious use 
of the knife. The 
knots should be 
cut off aud burned 
whenever they are 
found. They are 
most conspicuous 
in the winter, when 
the branches are 
not covered with 
leaves ; but when a 
tree is attacked, it 
is not wise to delay ,, 
the removal until a matube black knot. 
more convenient time. The diseased branches 
should always be burned, otherwise the spores will 
continue to form for awhile, and thus propagate the 
contagious pest. If the tree is badly attacked, it 
may be best to remove it entirely. 
The Choke Cherry is a favorite host of the black 
knot, as the neglected fence rows often show in 
winter. All such trees should be rooted out. 
The cultivated cherry trees are subject to attacks 
by the black knot, for which the same remedy as 
that for the plum tree is recommended. Use the 
pruning-knife, always at sight, and cut several 
inches below the swelling, that all the infested 
portion may be removed. Figure 1 shows a young 
knot shortly after the rupture of the swollen stem 
in early summer. A full-grown knot, with its ir¬ 
regular aud broken surface, is shown in figure 2. 
The Sheep Grub. 
During the hot days of mid-summer, sheep often 
huddle together with their noses upon the ground, 
or in some other constrained position. This is 
done, partly at least, to secure them from the at¬ 
tacks of the pestering Gad-fly ((Estrus ovis), which 
is the parent of the annoying Grub-in-the-head. 
This insect is closely related to the bot-fly, that de¬ 
posits its eggs upon the neck, shoulders, and fore¬ 
legs of horses, from which they are removed by the 
teeth of the animal, to allay the itching, and are 
taken into the stomach, and develop into the 
troublesome bots. The female sheep gad-fly aims 
to deposit her eggs in the nostrils of the sheep, 
and the animals, apparently aware of the effects to 
follow, try to prevent it. If the eggs are laid, they 
soon hatch, and the young grubs ascend the nos- 
