previous next

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 palm1 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 attended3 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, Worms5 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 pestilence9 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 birds10 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 delicacies11 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 fig12 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 the16 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. Cato18 says that the red moss19 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. Either21 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 names22 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. Scab23 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 harden25 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 pine27 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 off28 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 another29 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 Arcturus31 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 juices32 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 Atabulus33 that prevails in Apulia, and the Olympias34 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 dung39 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.

Varro42 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 improved46 even—such, for instance, as the pear known in Chios as the Phocian pear. We have already mentioned47 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 another48 by their shade, or the density of their foliage, as also by the withdrawal of nourishment. Ivy,49 by clinging to a tree, will strangle50 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 radish53 as his antidote for drunkenness, recommending it to be eaten on such occasions. The vine, too, abhors all coleworts and garden herbs, and the hazel54 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 beans55 and fitches act as poisons on the vine.

1 In B. xiii. c. 6.

2 In B. xiii. c. 47.

3 This is the opinion of Theophrastus, Hist. Plant. B. iv. c. 16.

4 In c. 2 of this Book.

5 "Vermiculatio." Fée understands this to apply to the attacks of insects in general, the Dermestes typographus more particularly.

6 Or, in other words, the evil influences of the heavenly bodies: this, of course, is not believed in at the present day.

7 Necrosis, in particular portions of the plant.

8 See B. xvi. c. 19. He alludes to an exuberant secretion of resin, in which case the tree becomes charged with it like a torch.

9 He alludes to the epidemic and contagious maladies by which trees are attacked. The causes of these attacks are often unknown, but they may probably proceed, in many instances, from springs of hot water, or gaseous emanations secreted in the earth.

10 The woodpecker more particularly. See B. x. c. 20.

11 It is not known, with certainty, what these worms or caterpillars were. The larva of the capricorn beetle, or of the stag-beetle, has been suggested. Geoffroi thinks that it may have been the larva of the palmweevil. This taste for caterpillars, probably, no longer prevails in any part of Europe.

12 This passage, which is quite conformable to truth, is from Theophrastus, Hist. Plant. B. iv. .16, and B. iii. c. 12.

13 See B. xvi. c. 80.

14 The effects produced upon young shoots by frost, are still so called.

15 Probably from the black colour which it turns.

16 In this case it would be very similar to what we call sun-stroke.

17 "Clavum," a nail. He appears to allude to a gall that appears on the bark of the olive, the eruption forming the shape of a nail, and, in some instances, a "patella," or platter. The Coccus adonideum is an insect that is very destructive to the olive.

18 De Re Rust. 6.

19 A sort of Erineum, Fée suggests. See B. xv. c. 6.

20 "Impetigo." "Tetter," or " ringworm," literally.

21 From Theophrastus, Hist. Plant. B. iv. c. 16.

22 σφακελισμὸς and κρͅάδος.

23 From Theophrastus, Hist. Plant, B. iv. c. 16. Fée is at a loss to know what is meant by these viscous dews, and is unable to identify the disease here mentioned as "scabies." It is not improbable that it was caused by an insect.

24 See cc. 35 and 50 of this Book.

25 See B. xviii. c. 69.

26 In c. 35. See also c. 45 of this Book.

27 From Theophrastus, Hist. Plant. B. iv. c. 16. If the terminal bud of the palm is taken off, it will mostly die.

28 Decidunt." The French use a similar word—couler. In this case the pollen, being washed off by the showers, has not the opportunity of fecundating the ovary of the flower.

29 The insect Ichneumon or Pupivora, probably, which breeds in the larvæ or else in the body of the caterpillar. The passage is from Theophrastus, B. iv. c. 16.

30 Caused probably by a maggot or moth passing from one grape or olive to another, and spinning its web in vast quantities. See Theophrastus, B iv. c. 17.

31 See B. xviii. c. 74.

32 On the contrary, this sweet juice is secreted by the insect itself, an aphis or vine-fretter.

33 The north-west wind. See Horace, Sat. B, i. s. v. 1. 71.

34 See B. ii. c. 46.

35 He probably means if applied to the bark of young trees.

36 The cork-tree forms no exception to the rule—if a complete ring of the bark that lies under the epidermis is removed, the death of the tree is the inevitable result. See B. xvi. c. 13.

37 Probably the Arbutus integrifolia. See B. xiii. c. 40.

38 This in reality is not the bark, but merely the epidermis, which is capable of reproduction in many trees.

39 See c. 16 of this Book.

40 This method, however, is often found efficacious in preserving the life of the oak, as well as many other trees, by excluding the action of the air and water.

41 It prevents them from increasing in height, but does not cause their death.

42 De Re Rust. B. i. c. 2.

43 In B. viii. c. 76, and B. xv. c. 8.

44 This statement is fabulous. Goats are apt to injure trees by biting the buds and young shoots. Fabulous as it is, however, Fée remarks that it still obtains credit among the peasantry in France.

45 This fabulous story is taken from Theophrastus, De Causis, B. v. c. 25.

46 Also from Theophrastus, Hist. Plant. B. iv. cc. 19–20, and De Causis, B. v. c. 22. It is just possible that on some of the branches being torn off by an animal, the tree may have grown with increased vigour.

47 In B. xiii. c. 9, and in c. 30 of this Book.

48 See B. xvi. c. 47.

49 It must be remembered that ivy is not a parasite, and that it has no suckers to absorb the nutriment of another tree.

50 See B. xvi. c. 62.

51 C. Bauhin gives this name to several species of Atriplex. Lacuna was of opinion that the Halimon of Dioscorides was the same as the Viburnum.

52 A superstitious belief only, as Fée remarks.

53 See B. xix. c. 26.

54 Virgil shared this belief: see Georg. ii. 1. 299.

55 This may be true in some measure as to nitre, alum, and warm seawater; but not so as to the shells of beans and pigeon-pease, which would make an excellent manure for it.

The Natural History. Pliny the Elder. John Bostock, M.D., F.R.S. H.T. Riley, Esq., B.A. London. Taylor and Francis, Red Lion Court, Fleet Street. 1855.

Creative Commons License
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 United States License.

An XML version of this text is available for download, with the additional restriction that you offer Perseus any modifications you make. Perseus provides credit for all accepted changes, storing new additions in a versioning system.

load focus Latin (Karl Friedrich Theodor Mayhoff, 1906)
hide Places (automatically extracted)

View a map of the most frequently mentioned places in this document.

hide Display Preferences
Greek Display:
Arabic Display:
View by Default:
Browse Bar: