CHAP. 37.—THE DISEASES OF TREES.
Having now treated sufficiently at length of the planting
and cultivation of trees—(for we have already said enough of
the palm
1 and the cytisus,
2 when speaking of the exotic
trees)—we shall proceed, in order that nothing may be omitted,
to describe other details relative to their nature, which are of
considerable importance, when taken in connection with all
that precedes. Trees, we find, are attacked by maladies;
and, indeed, what created thing is there that is exempt from
these evils? Still however, the affections of the forest trees,
it is said, are not attended
3 with danger to them, and the
only damage they receive is from hail-storms while they are
budding and blossoming; with the exception, indeed, of being
nipped either by heat or cold blasts in unseasonable weather;
for frost, when it comes at the proper times, as we have already
stated,
4 is serviceable to them. "Well but," it will be said,
"is not the vine sometimes killed with cold?" No doubt it is,
and this it is through which we detect inherent faults in the
soils, for it is only in a cold soil that the vine will die. Just in
the same way, too, in winter we approve of cold, so long as
it is the cold of the weather, and not of the ground. It is not
the weakest trees, too, that are endangered in winter by frost,
but the larger ones. When they are thus attacked, it is the
summit that dries away the first, from the circumstance that
the sap becomes frozen before it is able to arrive there.
Some diseases of trees are common to them all, while
others, again, are peculiar to individual kinds, Worms
5 are
common to them all, and so, too, is sideration,
6 with pains in
the limbs,
7 which are productive of debility in the various
parts. Thus do we apply the names of the maladies that prevail among mankind to those with which the plants are
afflicted. In the same way, too, we speak of their bodies being
mutilated, the eyes of the buds being burnt up, with many
other expressions of a similar nature. It is in accordance
with the same phraseology that we say that trees are afflicted
with hunger or indigestion, both of which result from the
comparative amount of sap that they contain; while some,
again, are troubled with obesity, as in the case of all the resinous trees, which, when suffering from excessive fatness, are
changed into a torch-tree.
8 When the roots, too, begin to
wax fat, trees, like animals, are apt to perish from excess of
fatness. Sometimes, too, a pestilence
9 will prevail in certain
classes of trees, just as among men, we see maladies attack,
at one time the slave class, and at another the common people,
in cities or in the country, as the case may be.
Trees are more or less attacked by worms; but still, nearly
all are subject to them in some degree, and this the birds
10 are
able to detect by the hollow sound produced on tapping at
the bark. These worms even have now begun to be looked
upon as delicacies
11 by epicures, and the large ones found in
the robur are held in high esteem; they are known to us by
the name of" cossis;" and are even fed with meal, in order
to fatten them! But it is the pear, the apple, and the fig
12
that are most subject to their attacks, the trees that are bitter
and odoriferous enjoying a comparative exemption from them.
Of those which infest the fig, some breed in the tree itself,
while others, again, are produced by the worm known as the
cerastes; they all, however, equally assume the form of the
cerastes,
13 and emit a small shrill noise. The service-tree is
infested, too, with a red hairy worm, which kills it; and the
medlar, when old, is subject to a similar malady.
The disease known as sideration entirely depends upon the
heavens; and hence we may class under this head, the ill
effects produced by hail-storms, carbunculation,
14 and the
damage caused by hoar-frosts. When the approach of spring
tempts the still tender shoots to make their appearance, and
they venture to burst forth, the malady attacks them, and
scorches up the eyes of the buds, filled as they are with
their milky juices: this is what upon flowers they call " charcoal"
15 blight. The consequences of hoar-frost to plants are
even more dangerous still, for when it has once settled, it
remains there in a frozen form, and there is never any wind to
remove it, seeing that it never prevails except in weather that
is perfectly calm and serene. Sideration, however, properly
so called, is a certain heat and dryness that prevails at the
rising of the
16 Dog-star, and owing to which grafts and young
trees pine away and die, the fig and the vine more particularly. The olive, also, besides the worm, to which it is equally
subject with the fig, is attacked by the measles,
17 or as some
think fit to call it, the fungus or platter; it is a sort of blast
produced by the heat of the sun. Cato
18 says that the red
moss
19 is also deleterious to the olive. An excessive fertility,
too, is very often injurious to the vine and the olive. Scab is a
malady common to all trees. Eruptions,
20 too, and the attacks
of a kind of snail that grows on the bark, are diseases peculiar
to the fig, but not in all countries; for there are some maladies
that are prevalent in certain localities only.
In the same way that man is subject to diseases of the sinews, so are the trees as well, and, like him, in two different
ways. Either
21 the virulence of the disease manifests itself in
the feet, or, what is the same thing, the roots of the tree, or
else in the joints of the fingers, or, in other words, the extremities of the branches that are most distant from the trunk.
The parts that are thus affected become dry and shrivel up:
the Greeks have appropriate names
22 by which to distinguish
each of these affections. In either case the first symptoms are
that the tree is suffering from pain, and the parts affected become emaciated and brittle; then follows rapid consumption
and ultimately death; the juices being no longer able to enter
the diseased parts, or, at all events, not circulating in them.
The fig is more particularly liable to this disease: but the
wild fig is exempt from all that we have hitherto mentioned.
Scab
23 is produced by viscous dews which fall after the rising
of the Vergiliæ; but if they happen to fall copiously, they
drench the tree, without making the bark rough. When the
fig is thus attacked, the fruit falls off while green; and so, too,
if there is too much rain. The fig suffers also from a superfluity of moisture in the roots.
In addition to worms and sideration, the vine is subject to
a peculiar disease of its own, which attacks it in the joints,
and is produced from one of the three following causes:—
either the destruction of the buds by stormy weather, or else
the fact, as remarked by Theophrastus, that the tree, when
pruned, has been cut with the incisions upwards,
24 or has been
injured from want of skill in the cultivator. All the injury
that is inflicted in these various ways is felt by the tree in the
joints more particularly. It must be considered also as a
species of sideration, when the cold dews make the blossoms
fall off, and when the grapes harden
25 before they have attained
their proper size. Vines also become sickly when they are
perished with cold, and the eyes are frost-bitten just after they
have been pruned. Heat, too, out of season, is productive of
similar results: for everything is regulated according to a fixed
order and certain determinate movements. Some maladies,
too, originate in errors committed by the vine-dresser; when
they are tied too tight, for instance, as already mentioned,
26 or
when in trenching round them the digger has struck them an
unlucky blow, or when in ploughing about them the roots have
been strained through carelessness, or the bark has been
stripped from off the trunk: sometimes, too, contusions are
produced by the use of too blunt a pruning-knife. Through
all the causes thus enumerated the tree is rendered more sen-
sitive to either cold or heat, as every injurious influence from
without is apt to concentrate in the wounds thus made. The
apple, however, is the most delicate of them all, and more
particularly the one that bears the sweetest fruit. In some
trees weakness induced by disease is productive of barrenness,
and does not kill the tree; as in the pine
27 for instance, or the
palm, when the top of the tree has been removed; for in such
case the tree becomes barren, but does not die. Sometimes, too,
the fruit itself is sickly, independently of the tree; for example,
when there is a deficiency of rain, or of warmth, or of wind,
at the periods at which they usually prevail, or when, on the
other hand, they have prevailed in excess; for in such cases the
fruit will either drop off or else deteriorate. But the worst
thing of all that can befall the vine or the olive, is to be pelted
with heavy showers just when the tree is shedding its blossom,
for then the fruit is sure to fall off
28 as well.
Rain, too, is productive of the caterpillar, a noxious insect
that eats away the leaves, and, some of them, the blossoms as
well; and this in the olive even, as we find the case at Miletus;
giving to the half-eaten tree a most loathsome appearance. This
pest is produced by the prevalence of a damp, languid heat;
and if the sun should happen to shine after this with a more
intense heat and burn them up, this pest only gives place to
another
29 just as bad, the aspect only of the evil being changed.
There is still one other affection that is peculiar to the olive
and the vine, known as the "cobweb,"
30 the fruit being enveloped in a web, as it were, and so stifled. There are certain
winds, too, that are particularly blighting to the olive and the
vine, as also to other fruits as well: and then besides, the fruits
themselves, independently of the tree, are very much worm-eaten in some years, the apple, pear, medlar, and pomegranate
for instance. In the olive the presence of the worm may be
productive of a twofold result: if it grows beneath the skin,
it will destroy the fruit, but if it is in the stone, it will only
gnaw it away, making the fruit all the larger. The prevalence
of showers after the rising of Arcturus
31 prevents them from
breeding; but if the rains are accompanied with wind from
the south, they will make their appearance in the ripe fruit
even, which are then very apt to fall. This happens more
particularly in moist, watery localities; and even if they do
not fall, the olives that are so affected are good for nothing.
There is a kind of fly also that is very troublesome to some
fruit, acorns and figs for instance: it would appear that they
breed from the juices
32 secreted beneath the bark, which at
this period are sweet. These trees, too, are generally in a
diseased state when this happens.
There are certain temporary and local influences which cause
instantaneous death to trees, but which cannot properly be
termed diseases; such, for example, as consumption, blast, or
the noxious effects of some winds that are peculiar to certain
localities; of this last nature are the Atabulus
33 that prevails
in Apulia, and the Olympias
34 of Eubœa. This wind, if it
happens to blow about the winter solstice, nips the tree with
cold, and shrivels it up to such a degree that no warmth of the
sun can ever revive it. Trees that are planted in valleys, and
are situate near the banks of rivers, are especially liable to
these accidents, the vine more particularly, the olive, and the
fig. When this has been the case, it may instantly be detected
the moment the period for germination arrives, though, in the
olive, somewhat later. With all of these trees, if the leaves
fall off, it is a sign that they will recover; but if such is not
the case, just when you would suppose that they have escaped
uninjured, they die. Sometimes, however, the leaves will
become green again, after being dry and shrivelled. Other
trees, again, in the northern regions, Pontus and Phrygia, for
example, suffer greatly from cold or frost, in case they should
continue for forty days after the winter solstice. In these
countries, too, as well as in other parts, if a sharp frost or copious rains should happen to come on immediately after fructification, the fruit is killed in a very few days even.
Injuries inflicted by the hand of man are productive also of
bad effects. Thus, for instance, pitch, oil, and grease,
35 if applied to trees, and young ones more particularly, are highly
detrimental. They may be killed, also, by removing a circular
piece of the bark from around them, with the exception, indeed, of the cork-tree,
36 which is rather benefitted than otherwise by the operation; for the bark as it gradually thickens
tends to stifle and suffocate the tree: the andrachle,
37 too, receives no injury from it, if care is taken not to cut the body
of the tree. In addition to this, the cherry, the lime, and the
vine shed their bark;
38 not that portion of it, indeed, which is
essential to life, and grows next the trunk, but the part that
is thrown off, in proportion as the other grows beneath. In
some trees the bark is naturally full of fissures, the plane for
instance: in the linden it will all but grow again when removed. Hence, in those trees the bark of which admits of
cicatrization, a mixture of clay and dung
39 is employed by way
of remedy; and sometimes with success, in case excessive cold
or heat does not immediately supervene. In some trees, again,
by the adoption of these methods death is only retarded, the
robur and the quercus,
40 for example. The season of the year
has also its peculiar influences; thus, if the bark is removed
from the fir and the pine, while the sun is passing through
Taurus or Gemini, the period of their germination, they will
instantly die, while in winter they are able to withstand the
injurious effects of it much longer: the same is the case, too,
with the holm-oak, the robur, and the quercus. In the trees
above mentioned, if it is only a narrow circular strip of bark
that is removed, no injurious effects will be perceptible; but
in the case of the weaker trees, as well as those which grow in
a thin soil, the same operation, if performed even on one side
only, will be sure to kill them. The removal of the top,
41 in
the pitch-tree, the cedar, and the cypress is productive of a
similar result; for if it is either cut off or destroyed by fire,
the tree will not survive: the same is the case, too, if they
are bitten by the teeth of animals.
Varro
42 informs us, too, as we have already stated,
43 that the
olive, if only licked by a she-goat, will be barren.
44 When
thus injured, some trees will die, while in others the fruit becomes deteriorated, the almond,
45 for instance, the fruit of which
changes from sweet to bitter. In other cases, again, the tree is
improved
46 even—such, for instance, as the pear known in Chios
as the Phocian pear. We have already mentioned
47 certain
trees, also, that are all the better for having the tops removed.
Most trees perish when the trunk is split; but we must except
the vine, the apple, the fig, and the pomegranate. Others,
again, will die if only a wound is inflicted: the fig, however,
as well as all the resinous trees, is proof against such injury.
It is far from surprising that, when the roots of a tree are cut,
death should be the result; most of them perish, however,
when, not all the roots, but only the larger ones, and those
which are more essential to life, have been severed.
Trees, too, will kill one another
48 by their shade, or the
density of their foliage, as also by the withdrawal of nourishment. Ivy,
49 by clinging to a tree, will strangle
50 it. The
mistletoe, too, is far from beneficial, and the cytisus is killed
by the plant to which the Greeks have given the name of
halimon.
51 It is the nature of some plants not to kill, but to
injure, by the odour they emit, or by the admixture of their
juices; such is the influence exercised by the radish and the
laurel upon the vine.
52 For the vine may reasonably be looked
upon as possessed of the sense of smell, and affected by odours
in a singular degree; hence, when it is near a noxious exhalation, it will turn away and withdraw from it. It was from
his observation of this fact that Androcydes borrowed the
radish
53 as his antidote for drunkenness, recommending it to
be eaten on such occasions. The vine, too, abhors all coleworts and garden herbs, and the hazel
54 as well; indeed it will
become weak and ailing if they are not removed to a distance
from it. Nitre, alum, warm sea-water, and the shells of beans
55
and fitches act as poisons on the vine.