Phylloxera

“ Excommunicated Insects.—À propos of the efforts in progress to destroy the phylloxera and other insect scourges in France, a writer in La Nature gives a curious bit of information relative to the way in which such pests used to be proceeded against when science, save so far as it could be made to agree with Romish dogmas, had no existence for the world. ”

“ Why the Insect is more injurious in Europe than in America.—Without going into particulars, several good reasons may be given to explain the fact that Phylloxera is more devastating in the vineyards of France than in our own. There exists a certain harmony between the indigenous fauna and flora of a country, and our native vines are such as from their inherent peculiarities have best withstood the attacks of the insect. ”

“ Thus, no one would think of having any mercy on the phylloxera, the pest of the grape-vine, but all would consider it a pious duty to destroy that baleful insect; and it is right to use every effort to hunt out the tigers and serpents of India. All the world is of one mind on these points. ”

“ Fig. 1.—Root-inhabiting Form (Radicola) of Phylloxera, with proboscis inserted into tissue of root of vine. numerous fusiform swellings are found upon the smaller rootlets. These are at first yellowish in colour and fleshy; but as they grow older they become rotten and assume a brown or black colour. If the roots on which these swellings occur be examined with a lens, a number of minute insects of a yellowish-brown colour are observed; these are the root-forms (radicola of Phylloxera (fig. 1) ”

“ A vine bruised by adversity is in no condition to withstand phylloxera. Therefore, since the adaptability of a variety to a soil or climate may be changed by the stock, the adaptations of stocks to soils and climates must have attention. ”

“ Amongst the numberless remedies that have been suggested and tried, with varying but by no means uniform or satisfactory results, for the destruction of the Phylloxera, may be mentioned sulphur, the sulphites, tobacco, caustic soda, and potash, bisulphide of carbon, coal-tar, soft soap, lime, the immersion of the vine in sulpho-carbonate of potassium, and the application around the roots of sand. ”

“ This submersion causes the death of the phylloxera at the roots of the plant. As a second method, through holes bored to the roots [294] the soil is injected with an asphyxiating fluid called sulphur of carbon, the fumes of which instantly kill all insects that they reach. The difficulty is to do a thorough job and leave no survivors. A third device is employed by those who import from America certain wild vines much hardier than our cultivated ones, but producing inferior fruit. These American plants resist the attacks of the phylloxera, and continue to flourish where our vines would succumb. ”

“ He thus brought the Phylloxera to Europe, not realizing beforehand that this little parasitic bug, though harmless to the American vine which puts out new shoots on its roots when the insect injures the old ones, is absolutely deadly to the European vine, which has not acquired the simple but all-important mode of growth by which the American vine is rendered safe. ”

“ They lay their parthenogenetically produced eggs in the angles of the veins of the leaves, in the buds, or, if the season is already far advanced, in the bark. In very damp or cold weather the insect remains in the ground near the surface, and deposits its eggs there. The eggs are very few in number and of two sizes, small and large (fig. 3, b and c) . From the larger a female (fig. 4) is hatched in eight or ten days, and simultaneously, for the first time in the life-history of the Phylloxera, a male (fig. 3) appears from the smaller egg. Neither male nor female has wings ”

“ Exposure to air and sunlight acts fatally to the Phylloxera, shrivelling and drying it up. Hence its instinct of self-preservation, no less than its search after its food, leads it to bury itself beneath the surface of the soil. But, as the insect does not possess an organisation that fits it for burrowing, the character of the soil has a great deal to do in affording facilities or the reverse favorable to its existence. ”

“ While, therefore, there is much yet to learn in the life-history of our Grape Phylloxera, the facts which I have already unequivocally stated, as well as those which I shall now proceed to give, remain indisputable, and do not seem fully to accord with Balbiani's discoveries.
As fall advances the winged individuals become more and more scarce, and as winter sets in only eggs, newly-hatched larvae, and a few apterous egg-bearing mothers, are seen. These last die and disappear during the winter, which is mostly passed in the larva state, with here and there a few eggs. ”

“ The patient generally believes himself to be the victim of persecution.
The efficacy of the alkaline sulpho-carbonates as a means of exterminating the phylloxera appears to have been demonstrated by experiments made by Mouillefert, at the instance of the Paris Academy of Sciences. It still remains, however, to devise suitable methods of employing this insecticide. "Science," says M. Mouillefert, "has accomplished its mission, and it is now for agriculture to perform its part." ”

“ If we enquire further why the Phylloxera [157] epidemic was so much worse in the Southern vineyards than in the more Northern ones of Germany, the opinion seems to prevail that the warmer climates favour the insect. Further, it appears that, in Italy, the vines in loose open soil, provided it is equally rich in mineral food-materials and offers no disadvantages as regards drainage, suffer less than those in closer soils, the reasons alleged being that the young roots can push out more rapidly and widely, and so obtain holdfasts with greater distances between them. ”

“ Again, the male of Phylloxera vastatrix lives for a much shorter period than the female, and is devoid of proboscis and stomach, and takes no food: it fertilizes the female as soon as the last skin has been shed and then dies. ”

“ Decay usually follows its work on the roots and is often more injurious than the harm done directly by the parasite. This decay is always much more serious on European vines than on those of our native species. The phylloxera is a native of the United States east of the Rocky Mountains, from whence it was introduced into France and from France into California, where it causes much greater damage than elsewhere in the United States. Wherever the pest is found, it is more injurious in heavy than in sandy soils. ”

“ The agricultural interests of the south of France have been nearly ruined by the substitution of the artificial alizarine for madder in dyeing, the silk-worm disease, and the phylloxera. The cultivation of madder will have to be given up, for it can not again be made profitable. The disasters wrought by the silk-worm disease and the phylloxera, now that remedies have been discovered, may be repaired in time. ”

“ The males in all plant-lice are quite rare, and, in the great majority of species, unknown. Where known, this sex bears about the same relation to the female as the shorter and smaller Phylloxera just described does to the larger. These same differences observed in the winged insects obtain in the other species of the genus that are known, and have always been looked upon as sexual. Signoret, an authority on these insects, once so looked upon them, [11] but has lately declared the shorter form to be a female emptied of her eggs. ”

“ Phylloxera has been treated by plunging into the soil near the roots small blocks of some slowly-soluble medium, such as gelatine, impregnated with carbon-bisulphide, the volatile fumes of which kill the insect, and even more drastic remedies have been tried along similar lines. In America orchard trees infested with insects or fungi have been covered one by one with light tents, and the vapours of prussic acid, burning sulphur, and other poisons allowed to act inside the tent. ”

“ The war against the phylloxera in France has been waged with wonderful vigor, and has resulted so far in redeeming more than half of the infected country from the attacks of the pest. The methods of fighting employed are first, submersion of the whole land until the invaders are drowned—the most effective method, but applicable only to low lands ”

“ Munson, one of the best American authorities on the resistance of species to phylloxera, says: [7] "Rotundifolia is entirely immune, then Rupestris, Vulpina, Cinerea, Berlandieri, Champini, Candicans, Doaniana, Æstivalis and Lincecumii are so high in resistance as to be practically uninjured, though they may be attacked, while Labrusca is low in resistance and is much weakened in clay soils, if infested, and Vinifera is entirely non-resistant." Some of these species are hard to propagate and difficult to suit in soil and climate so that but two of them are much used for resistant stocks. ”

“ Several species are involved, but only one, known as the pecan phylloxera, causes serious damage. It causes twigs to become malformed, weakened and finally to die, and destroys the crop on the infested terminals. The insect passes the winter in the egg stage in protected places on the trees. The young appear in the spring about the time the buds begin to unfold. ”

“ Hence, since only female-producing sperm remain, all fertilized eggs (sex-hybrids) must develop into females.
In the case of Phylloxera, where many generations of wingless parthenogenetic females appear while environmental conditions remain favorable, and when these become adverse, give way to winged males and females. Dr. T. H. Morgan has discovered a similar degeneration of the male-producing spermatozoa and the loss of a chromosome in the parthenogenetic males. ”

“ A very disastrous root-disease of the vine is due to the ravages of another pyrenomycetous fungus, Rosellinia (Dematophora) necatrix (fig. 6) , which forms subterranean strings of mycelium so-called rhizomorphs. The diseased roots have been confounded with those attacked by Phylloxera. The only mode of combating the malady seems to be to uproot the plants and burn them. Isolation of the diseased areas by means of trenches has also been practised. ”

“ Diseases of the Vine.—The vine is subject to a number of diseases some of which are due to micro-organisms (moulds, bacteria) , others to insect life. The most destructive of all these diseases is that of the phylloxera. The Phylloxera vastatrix is an insect belonging to the green fly tribe, which destroys the roots and leaves of the growing plant by forming galls and nodosities. Practically every wine-growing country has been afflicted with this disease at one time or another. ”

“ The phylloxera having destroyed many of the finest vineyards in Europe, it would seem that Americans have the best of chances to supply the world with high-class wines, for there is not a State in the Union where the vine will not flourish. Here its worst enemy is mildew, a parasitical fungus which attacks the leaves, revealing itself in yellowish-brown patches on the upper side, and thin, frosty patches underneath. ”

“ The more Manifest and External Effects of the Phylloxera Disease.—The result which follows the puncture of the root-louse is an abnormal swelling, differing in form according to the particular part and texture of the root. These swellings, which are generally commenced at the tips of the rootlets, where there is excess of plasmatic and albuminous matter, [15] eventually rot, and the lice forsake them and betake themselves to fresh ones—the living tissue being necessary to the existence of this as of all plant-lice. ”

“ Phylloxera.
Winged female which lives on leaves and buds an lays parthenogenetically eggs of two kinds, one developing into a wingless female, the other into a male.They moult five times, becoming with each change of skin darker in colour; in about three weeks they become adult and capable of laying parthenogenetic eggs. In this way the insect increases with appalling rapidity: it has been calculated that a single mother which dies after laving her eggs in March would have over 25,000,000 descendants by October. ”

“ For a period—from the middle ’seventies to the ’nineties of the 19th century—the cognac industry was, owing to the inroads of the phylloxera, threatened with almost total extinction, but after a lengthy series of experiments, a system of replanting and hybridizing, based on the characteristics of the soils of the various districts, was evolved, which effectually put a stop to the further progress of the disease. ”

“ But alarm has been caused by the appearance of phylloxera, in 1885, at Mansura, near Tlemccn, and afterwards in the Sidi-bel-Abbes district. A more formidable scourge of long standing are the locusts, which are hatched in countless myriads on the steppes, where they are salted down and consumed as food by the nomads. A flight of moderate size observed in the Medea district in 1874, formed a compact mass 15 by 2^ miles, or 40 square miles in extent, comprising at least fifty billions of these winged pests. ”

“ It may be the terrible insect called the phylloxera that destroys the growth of the vine, it may be mildew, or it may be over-production, but any of these troubles bear hardly upon the vine-grower, who is, broadly speaking, a humble type of peasant with very little capital. ”

“ They are active, supple creatures, and turn up menacingly the posterior part of the body when disturbed. They are found in several different kinds of Phylloxera-galls, and do more than any other species to keep the leaf-inhabiting grape Phylloxera within bounds.
The next most efficient aid in the destruction of the leaf-lice is found among the lace-wing flies, one species of which, more especially, viz., the Weeping Lace-wing (Chrysopa plorabunda Fitch) , I find very frequently within the galls, devouring their contents. These ”