Woolly Aphis

Horowhenua Chronicle, 14 November 1916, Page 3

Woolly Aphis

Mr J. A. Campbell, Assistant Director of the Horticultural Division of the Agriculture Department, writes as follows in the civrrent issue of the "Agricultural Journal" concerning "the woolly aphis pest:—

Summer treatment for woolly aphis is carried! out mainly with the idea of keeping the diiscaso within bounds until the stronger winter remedies can be applied. This is the utmost good that can be expected of the summer treatment, ns the eradication of the aphis is a matter that can only be attended to properly when the tree are dormant. It will also, in order to be en tiro'y successful, require a great anon nt of care and supervision, and is practicable only as far as trees up to a moderate size are concerned. This refers to pa'nting the aphis colonies with strong oil emulsion, and. to the renewal of treatment immediately a fresh outbreak is observed. Where practicable this is an excellent remedy and one which, if regularly applied to young trees, would save much labour and trouble. In respect to large trees which have long he°n affected, the only practicable remedial treatment up to the present is that of spray ng. To what extent spraying is successful depends mainly on Ihe material used nndi the manner in which it <is applied Oil emu'sicn is now the recognised remedy for aphis, and owing to its value in this respect many varieties of apples, can now be very successfully grown in localities where similar varieties bad previously to he destroyed owing to at tackH from aphis.

Although oil spraying is regularly

adopted there is still sonsiderable difference of opinion in regard to the strength of mixture and the time of application. In this resect there has been •a. general tendency diirrf'ng tlie Inst few seasoins towards increasing the strength very materially, particularly in spraying pipfruits; but there are also undoubtedly many who still use the oil sprays at too weak a strength. La rge numbers of growers strongly favour one thorough dressing of oil, at the ratfo of 1 in 8 or 1 in 12. applied when the trees are quite dormant ,ns being the most satisfactory all-round winter remedy for all suck ing insects. For the control of woolly aphis others particularly favour two applications of oil at a considerably reduced strength—l in 26; tlie first application as soon as the foliage lias sufficiently fallen to allow of thorough work being carried out, a.ndi the other just before the buds burst. For general purposes I should recommend the single application, but there is no doubt that the double application has resulted "very satisfactorily in the control of the aphis. The drawback to this method, however, lies in the fact that the spray used is for too weak to gj've satisfaction with either mussel scale or red mite. If the second aplication was increased to 1 in 12 or 1 in 15 the main points of both ideas fould be carried at the expense of a little more material on the one hand and labour on the other.

Summary.—To sum up, the sprays recommended for the control of the I'iseases mentioned are as follows:

For die-back of the pencil, spray ■with 8-6-40 Bordeaux mixture as soon as possible after the foliage lias fallen. . For die-back of the peach awl .San Jose scale, spray with lime-sulphur solution at the rate of 1 in 15 as soon as possible after the foliage has fellen. For woolly aphis spray with oil emulsion at the' rate of 1 in 25 as soon as the foliage has fallen sufficiently tallow of the work being properly carried out.