Source: Turin Phylloxera Council   Leave a comment

The following text ‘The Turin phylloxera council: ideas as to the phylloxera and rules for watching the vineyards‘ by the council secretary, ‘Professor Jemina’ was translated into English by Her Majesty’s Government in 1887. It gives us a glimpse of the first phylloxera crisis in Italy. SY

An important branch of the produce of the nation, the cultivation of the vine, has been seriously and continually threatened from the moment when the Phylloxera appeared in Italy. We have now in our midst the enemy of the vine who before was at our doors, and although warned by authorities on the subject to hold ourselves in readiness for so sinister a visit, yet the fear when once awakened is not slight. Happily, however, our present position is much more favourable than was that of France, for that nation remained in ignorance of the gravity of the danger from 1863, the year in which the damage due to the Phylloxera became apparent in the department of the Gard, until 1868, when the illustrious Planchon discovered the evil and studied the characteristics of the destructive insect. During this period the cultivation of the French vine continued, and the evil spread with rapid strides. But we, knowing the danger, shall be able in great part to avoid it. Moreover, France had not ready at hand powerful antidotes such as are now known, and later on she awoke to the necessity of destroying the original centres of infection. To this must be added the facts that much of our vine cultivation is considerably more scattered than in France, and that Italy having to fight against Phylloxera finds herself in a more favourable position, being abundantly supplied with American vines, which arc known to resist the disease. The Italian Government proceeded at once with the most efficacious means that science and the practical experience of neighbouring countries could suggest, and as far as lay in its power, to destroy the original centres of infection in various parts as they became apparent, and it will proceed, we hope, in the same way to destroy other centres as they continue to become apparent; and so, inch by inch, the ground will be contested with the destroying insect, and our vine culture will be for several years safe from the terrible scourge, giving us time to prepare ourselves for the greater damages against which we may have to bear up in the future, and saving from serious and unlooked for financial confusion those districts in which the vine is the principal, and in some of them the single resource. To effect this the Government alone will not suffice – the assistance of private cultivators is required; each ought to watch his own vineyards, and be able to discover at once doubtful cases of an invasion of Phylloxera, and then to continue a careful inspection. To the cultivators of the vine in the associated provinces we therefore offer these short practical instructions, forming a summary of the gist of information which they ought not to ignore.

What is known of the Insect; its different stages and ways of multiplying itself. The Phylloxera or vine louse is a small insect similar to the grubs which live on the tender buds of the rose, the peach, &c., and like them nourishes itself by means of a sucker, which it attaches to the vegetable tissue, and thus absorbs the nourishing juice of the plant. It was introduced into Europe from North America, where it lives upon the vines of that country, which, owing to the structure of their roots, offer a greater or less degree of resistance to the enemy. The Phylloxera can live on the leaves of the American vine, and produces nut-galls, and then it takes the name of ‘galli-cola’; ‘but on the European or home-grown vines it lives generally on the roots, which it damages or alters in a peculiar way, and then it goes by the name of Phylloxera ‘radicicola’. Let us then give our special attention to the Phylloxera which lives upon the roots, that being the form of the disease which is of the greatest interest to us, inasmuch as it is that which injures our vines. (1) In the spring there issues from an egg, deposited in the previous autumn at the foot of the vine, where it has passed the winter, a very small insect, which travels underground to the end of the most delicate roots, and there nourishes itself by sucking the sap from the vine. It increases in size, changing its skin three or four times (in the same way as the silk-worm during its periods of sleep), and develops into a female without wings, able when full grown to deposit eggs of her own free will. The eggs, a few days after being deposited, open, and the young are born, forming small colonies round the mothers. The young nourish themselves, grow, change their skins, and become, in their turn, so many adult females, able to deposit new fecund eggs. Each female can, between the spring and the autumn, produce from 8 to 10 families in succession, each consisting of from 30 to 40 eggs, so that from a single egg, supposing that all the insects born should continue to live, there would be at the end of the year a production of several thousands of millions. (2) Some of the females above-mentioned pass in the month of July or August into the chrysalis state (like the silk-worm when in the cocoon), and after some time they change their skins, issue from the earth with wings, and aided by the wind, they fly to a greater or less distance, and deposit four or six eggs on the under-side of the leaves of the vines. (3) Some of these eggs are of a larger size, and become female insects without wings; others are smaller and become males without wings, hatching in a few days. Insects of this breed, a sex distinct by itself, do not feed upon the vine, but are destined for breeding only. The male dies after a short time. The female deposits a single egg on the stem of the vine underneath the bark, and afterwards dies too. It is from this egg which passes through the winter, and is not hatched until the following spring, that our biology of the insect begins. (4) ‘We have said that of the females found on the roots all do not develop wings; some in fact at the end of the autumn cease to nourish themselves, retire from active life, pass the winter motionless on the roots, and are said to be ‘hibernating’. On the arrival of spring they take a new lease of life, and continue the process of development. For the sake of brevity let us cease to point out further distinctions not required for the object which these short instructions have in view.

Damage done to the vines by the ‘root’ Phylloxera (radicicola), and how it extends. The Phylloxera on the extremities of the roots produces a special and very characteristic kind of swelling which continues to change, or rather to rot, and the vine no longer able to nourish itself, dies. During the first year the Phylloxera is generally found on the most slender roots; afterwards it is found on the ramifications of the roots next in slenderness, and also on the thickest, and on that part of the stem which is under the soil, and it remains there until the vine dies. The Phylloxera then leaves it, crossing the cracks in the soil by itself, and proceeds to other neighbouring vines, where it finds new nourishment, and thus it is that the evil is spread ‘by diffusion’: it spread as a spot of oil upon paper, and is called the Phylloxera ‘spot’. Then, meanwhile, the vines which are, as it were, in the centre of the spot sicken, sprout less, remain stunted, and in the vineyard have a depressed and drooping appearance. This becomes more apparent when the stems of the vines are near each other. But the disease may be spread to a distance by means of  dissemination,” creating new centres of infection, either by means of the flying insect, or through the agency of man himself, who carries the Phylloxera which lives on the roots, from one place to another to great distances, on plants or some other object coming from an infected vineyard.

How the presence of the Phylloxera can be detected in a vineyard. During the first year of the disease the vine gives few or no signs of deterioration; but when the roots are laid bare distinct swellings or knottings are discernible at the extremities of the most minute of the roots, swellings so characteristic of the disease as to be recognizable by a peasant himself when once seen. During the second year, if the vine is strong, it makes an effort to put forth new roots, tender or capillary, but as soon as the Phylloxera gets upon these, death is inevitable, and the vine gives external signs of dying away either in the spring or in the summer. In the third or fourth year the vine generally dies. In the second or third year the ‘spot’ begins to be apparent in the vineyard if the vines are a slight distance apart, and the drooping or ‘Phylloxera depression’ which we pointed out above, in other words the dying away and the disease of the vines, proceeds in the direction of the lines if these are some distance apart. These facts, however, are influenced by the climate, by the nature of the soil, and by the strength of the vines, as, for example, in the neighbourhood of Pallanza the deterioration of the infected vines was but little apparent, owing to the relatively greater power of resistance possessed by the Isabella vines cultivated there, as compared with the European vine cultivated elsewhere.

To resume, we have:

External characteristics.

Backwardness in sprouting.

Leaves of a yellowish colour, and of a size below the average.

Budding stage of less than average duration.

Grape matured with difficulty.

It is worthy of remark, however, that similar symptoms are sometimes due to other diseases produced by cryptogamy, but with careful inspection these are easily to be distinguished. Nevertheless the presence of other diseases does not exclude the possibility of the existence of Phylloxera. Less easy of detection is the winter egg on the stem under the bark, and the eggs deposited in the autumn by the winged Phylloxera on the underside of the leaves.

Characteristics of the roots. The characteristics of the roots are much more important and easy to recognise.

(a). A swelling of the slender roots, the capillary, especially during the first year of the disease. During the first formation they are of a yellowish orange colour, but afterwards they grow black, and then rot towards the end of autumn, and become loss apparent.

(b). The ‘root’ Phylloxera resembles fine grains of yellow sand, visible to the naked eye of an expert, but more so with a lens. As winter approaches the ‘root’ Phylloxera passes to the ‘hibernating’ stage, grows darker in colour, and consequently becomes less apparent. They are no longer found on the roots near the surface, but penetrate deeper into the soil to escape from the cold. It is hardly necessary to add that the Phylloxera is not found on dead vines, since they would find there no nourishment, and they are rarely found on those that are dying away.

Steps to be taken by the cultivator of vines to avoid the introduction of the Phylloxera into his vineyards. To take no plant, no matter what, which comes from a place infected or under suspicion, a thing moreover prohibited by law. To confine himself to increasing the number of the local vines.

How to discover the presence or suspicions signs of the Phylloxera. Inspect, here and there, in different parts of the vineyards the roots of some of the plants, with a view to acquiring a thorough knowledge of the construction of the sound roots in their normal condition, and the power of distinguishing them as occasion requires from those which show the swelling characteristic of the Phylloxera. It will be sufficient, in order that the lower parts of the roots of the vines may not be injured by the inspection, to examine them with a hoe, at one side at the feet until the first crowns of the roots are reached; this during the summer, but during the autumn and the winter the examination must be carried deeper below the surface. The following must especially be visited: Vines that are dying away or sickening, or that are in the neighbourhood of vines that are dying away, vines that are purchased away from the estate, and vines in gardens where ornamental vegetation exists. In cases of suspected Phylloxera the local authorities should be at once informed, and specimens of the roots under suspicion, both of the slender and of the thicker kinds, should be gathered from different vines. These roots should be placed in a tin box with a closely fitting lid, and a ticket should be attached to the box giving the names of the locality and of the proprietor of the vineyard. When reasonable suspicion of Phylloxera exists, the authorities will provide for the examination of the roots, and will have the vineyards inspected by the persons appointed for the purpose.

This short pamphlet, in which we proposed to set forth the essential points which the practical cultivator of the vine ought to know, has no other object than to inspire the reader with a desire to make himself better acquainted with a subject of such great importance. Among the many publications worth consulting, we especially recommend the official report of the Ministry of Agriculture, No. 11, ‘Information and Directions as regards the diseases of the vine louse and of the Phylloxera.’ In this little work are reproduced two woodcuts showing 1. The Phylloxera in the egg, lava, chrysalis and winged insect stages. 2. The leaves of the American vine with the nut-galls. 3. The Phylloxera on the vine roots. 4. The various characteristic swellings of the capillary roots. These woodcuts are owed to the courtesy of Signor Franceschini, the Government Phylloxera Commissioner for the province of Milan, and already form a part of his work on the Phylloxera.

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Posted December 16, 2010 by zachmon in Uncategorized

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