New Zealand Department of Agriculture.

Manawatu Herald, 6 July 1897, Page 2

New Zealand Department of Agriculture.

JOHN D. BITCHIB, Secretary. LEAFLETS FOR GARDENERS AND FRUITGROWERS, NO. 20. By T. W. Kirk, F.R.M.S., F.L.S., &c, Lond., Government Biologist. VINE-LOUSE {Phylloxera vastatrix.) Plate I.

Fig. 1. Portion of root of diseased vine, showing numerous swellings on the rootlets caused by Phylloxera (reduced); from nature; specimens obtained in Auckland by tiignor Bragato. Fig. 2. Young Phylloxera viewed from below. Pig. 8. The same from above. Fig. 4. Phylloxera puncturing the bark of a root with its rostrum. Pig. s(a and &). Female and male eggs of winged Phylloxera; (c) Egg of wingless Phylloxera. Fig. 6. Male, sixth metamorphosis. Fig. 7. Female, sixth metamorphosis. Fig. 8. Egg-laying, female and egg. Fig. 9. Adult root-form (radioole) from below. Fig. 10. Adult root-form (radicole) from above. Fig. 11. Boot-form before turning to nymph. Fig. 12. Nymph. Fig. 13. Sexual Phylloxera, male. Fig. 14. Sexual Phylloxera, female. Fig. 15. Winged Phylloxera. With the exception of Fig. 1, which is from nature, the whole of the cuts on this plate are reproduced from the article by Mr Despeisses above cited. No. lia reduced; all others greatly magnified. Plate 11.

Fig. 1, 2, 3, 4. Boot feeding viviparouily-prodaced forms, viewe d from below. Fig. 5 Head of Fig. 3 from above, showing the three-jointed antema, the character of the genus. Figs. 6, 7, 8. Showing the forms of the last joint of the feet of the animal drawn on Fig. 3. Fig. 9. Outline of egg. Fig. 10. Another specimen in an advanced state. All figures from nature.

In the scales given each division represents 1 in IOOOin. Figures I. to V. are not drawn to scale, and are intended only to illustrate the following short notes, showing something on the rate of propagation of viviparous forms in New Zealand: — I. 21st April, 6 p.m.—Fathogenetic female and newly-born viviparous offspring observed. Whether the offspring left the body of the parent I head-first or not is not apparent, but it certainly emerged from the shelter , of the body head-first. j 11. Twenty minutes later a second ! offspring was observed leaving the shelter of the parent, but on the opposite side and near the head, the parent tilting to the left to allow it to emerge. No. 1 young had slightly Utered its position ai shown. 111. Shows the appearance of the /

second offspring ten minutes later, At 6.50 neither of the offspring had quitted the shelter of the parent. At 8.20 No. 2 had withdrawn nnder the body of the parent, which had the abdomen closely pressed to^ the root, At 9.45 the relative positions were unchanged. 22nd April.—There was no appre* ciable change observable during the whole day. IV. 28rd April, 9.60 p.m. The first offspring had almost completely emerged from the shelter of the parental body, and had grown to fully two-thirds the size of the parent, No. 2 which had retired under the parent at 8.20 p.m. on the 21ft, is still invisible. V. 24th April.—Examined at 9.80 p.m. No. 1 bad grown a little, while No. 2, which yesterday was invisible, had quite emerged from the

parental shelter, and was observed at a little distance, attached to the root and feeding. On the appearance of Phylloxera in 1890, opinions were expressed that the New Zealand insect was not Pi veitatrie, and this opinion was founded on the fact that in the larval form the rostrum or break was very much longer than shown in the figures and descriptions of that insect published by the best authors. The length of the rostrum at this stage is certainly remarkable (see Figs. I^4, Plate II.) ; but, as it certainly was not either of the other species which feed on oaks, it followed'that if not P. vestatrix, then it must be new. This point could not be settled from the specimens which I received in 1890, but the mode of attack and the way in which the vines suffered were so identical with the results of the depredation of P. testatrix as to make it evident that, whatever the specific nature of the insect .the same treatment should be adopted as if the visitant were undoubtedly P. vettairix. I drew Signor Bragato's attention to ! tlri3 particular point, and after examination he expressed himself as positive that the specimens he secured were .identical with the vinelouse (P. vettatrix), with which he was familiar both in Europe and Australia. I am glad to be able to state that since then specimens from Auckland, which were kept, under observation, bad in November developed, and show the short rostrum of the typical form. See (Figs. 1 and 2.) 1 2 The only forms observed at this date were the egg-laying females busily engaged in laying eggs, of which one female had upwards of forty round her, all being connected by a cord ; the newly-hatched viviparous forma undergoing their earliest moults, and ' the testudinate nicies. The winged form I have been unable io far to secure. The life-history of Phylloxera gives briefly the complete cycle of both forms — i.e., gallicole (leaf) and radioole (root). So far, however, the leaf-form has never been observed in Australia or New. Zealand. It must be remembered that during winter living insects are found on the roots only, but the egg mentioned under the heading '" Seventh Metamorphosis " is at that time on the wood. On American vines Phylloxera causes great damage to foliage and but little to root ; yet, when introduced into Europe, the rooUform worked havoc, while the leaf- form waa, comparatively speaking, but little injurious. The same, as al» ready pointed out, holds good in Australasia, probably because few American vines are grown. This is a strong argument in favour of using the American vine, which is re* tiaUnt to the root-form of the insect, as a stock, and grafting on the European vines, which are but little troubled with the leaf-form. This, however, will be more fully mentioned another time. Before passing to the consideration of the steps necessary for preventing- the distribution of the pest to clean districts, and its extirpation from those localities in which it at present exists, I desire to record my sincere thanks to my brother, Mr H. B. Eirk, M.A., for keeping the specimens of Phylloxera under care* ful microscopic observation during my absence from Wellington, and executing sketches of various* stages of development. Prevention of dissemination : — 1. Avoid cuttings and young plants from infected axeas. As already explained, near the end of rammer the so-called winter egg is laid in any crevice or crack in the j bark, usually of young wood, where it remains till spring, when the

young insects emerge, descond to the roots, and at once begin to breed. It Will therefore be seed that great risk is run if cuttings from infected localities are used, while rooted plants may carry tha pest in its adult form. 2. All cuttings should be dipped in some solution which will destroy the egg. The following is strongly recommended - namely : In an ear« tbenware vessel prepare a solution of 4oz. of sulphate of potash, to every S gallons of water, and immerse the cuttings in this for twenty minutes. . 8. If possible, graft on to American resistant stocks, of which Vitis riparia ia generally admitted to be the best. Some years ago the Government imported a considerable quantity of resistant stocks, which were distributed to Northern settlers, and several nurserymen. The latter propagated considerable quantities, but one of them informed me that there was no demand, and that in the end he had to throw them away. I had intended giving a resume of the methods adopted in other countries to check the Phylloxera ; but, being strongly of opinion that, whenever this fell pest makes its appearance on a property, the Government should, in the interests of all concerned, step in and conduct the work— of course, free of cost to the owner, save that in bad cases he might have to sustain the destruction of his vines — it does not seem necessary to occupy more space here with an account of processes with which the officer placed in charge of the work would, of course, be quite familiar. I Note. — Since the above was in type it has been decided that the Government will undertake the treatment of infected vineries, as above suggested. This, together with the enormous loss sustained by vignerons in the older countries aud Australia, should induce any person suspecting the presence of Phylloxera in a vineyard to report to the Government without delay.