PEACH BLIGHT.

Wairarapa Daily Times, Volume VII, Issue 2131, 28 October 1885, Page 2

PEACH BLIGHT.

We take the following from the report on fruit blights presented to Parliament by Professor Kirk The peach is liable to the attacks of numerous fungoid and insect enemies capable of effecting aserious diminution in the yield, and of exhausting the energies of the tree ; but the total amount of injury caused by these unwelcome parasites during a long series of years would t|e, bi)t trifjing when omnpared with the wholesale destruction that has overtaken the peach throughout the colony, and to which the term ''peach blight" is generally applied. Thousands of acres of peach orchards and plantations in the North Island have been destroyed —the grand peach groves of the Maorins in the flokianga, Kaipara, Waikato, Napier and Wanganui Districts are things of the past, and the peach itself, once the commonest fruit in the colony, has now bqcomo tho rarest, It is no exaggeration to say that, by the destruction of the peach, the value of the yearly food supply of the colony been diminished to the extent of thousands of pounds, The first-symptoms of peanhblight are usually exhibited after cold winds during the flowering season, and and before the full development of the leaves. The ovaries swell until the younp fruits attain the size of a large pea, when a sudden arrest of growth takes place and they drop from the trees, in many cases not even a solitary fruit being left. The leaves also fall away -without attaining tlieip ful} development, At or before this time orange-colored dots of punctures, doubtless of a fungoid nature, are formed upon the young twigs, and in some instances become confluent, ultimately leading to the disintegration of the bark, followed by an exudation of gum at the affected parts. The buds decay and become infested with thrip or other insects to a greater or less extent, the bark becomes shrivelled, and the effected shoot dies. As a general rule, the lower branches are effected before the upper. Sometimes the tree is killed by the first attack, bu| usually, oi) tlje approach of autumn, new leave's are produced towards the tips of the young shoots. Although in many oases the new leaves are attacked by a fungus, the plant seems in a fair way for recovery, but in the following spring the same sequence of incidents occurs", and sooner or later the tree dies. All the symptoms enumerated afford evitlenco that the constitution of the plant has become weakened; the vital processes are not properly pefornied, so that the plant is not only'unable to endure sudden changes ot temperature, but is more liable to the attacks of fungi and insects, while it hap less power to resist them. Amongst the fagts' wjtlcit may bp ajjcfuced jji support of this view, the following may be selected: —(1) The simultaneous ap» pearance of the decay in various parts of the colony, its rapid extension, and uniform results. (2) The similarity of results in other countries where the peach has received similar treatment. (3) Trees are destroyed at all periods of growth, from seedlings a few inches in height to trees in full bearing. (4) No external conditions can ensure safety. Trees in sheltered positions suffer in the same manner as tlioao fully expqsei although in M"} 6 instances a sheltered position appears'to retard the prqgress of exhaustion. On the other hand, trees grown in sheltered positions are speedily exhausted when the shelter is removed. (5) If the demand upon the vital energies qf an affected tree is reduced by removing a portion of the branches, the remaining branches usually exhibit an improved appearance, although of a temporary

character, ((j) If a tree be headed down when first seen to be affected, luxuriant and . apparently healthy branches. ai'6 speedily given off from the stump, but this also is only temporary; the old signs of weakness are usually exhibited the following spring, if not before. This weakening of the vital energies of the plant has boon mainly effected by growing peaches on their own roots, and is to be seen in all countries where such a course has been followed. This is notably the case with the old Maori peachgroves, where one generation of trees after another has grown up from seed, and the same may be said of the cultivated trees in the orchards and gardens of the settlers. All the peach-trees in the colony have been either raised from seed or have been worked on peach-stocks. The first step in the work of renewal will be the selection of a suitable stock, and this we find is the mussel-plum, the stock invariably adopted by English nurserymen, who havo to carry on the cultivation of the peach under far liioro unfavorable climatic conditions than prevail with us. It is advisable that the new stocks should be worked with buds taken from sound healthy trees. Trees of one year's growth from the buds could be purchased in England at £5 per one hundred, so that a few hundreds might easily be imported with a quantity of stocks. The dying trees might, be cleared away at once, and a new start made on a satisfactory basis. Trees worked on mussel would bo more hardy, better able to resist adverse influence, while their productive powers would be increased rather than diminished. They would not be exempt from the occassional attacks of curl or other fungi, nor from the numerous insect pests that infect the peach, and they would still be subject to chauacs of temperature during the flowering season; but I do not hesitate to express my belief, whatever may yet be discovered weth regard to the decny of the peach, that the adoption of the mussel-stock would once more allow of its profitable cultivation. Whatever new fact might be brought to'light by a careful examination of the phenomena to be observed in the?spiing, the adoption of a new stockpiles at the base of all remedial measures, In an American nursery I observed two healthy trees-the only treeg absolutely healthy there; all the young stock, even the seedlings still in the seed-bed, being badly affected.' The two healthy specimens were worked on mussel - stocks. Three varieties of peacli are stated by some to be "blight-proofthe Comet, Solivay, and Early Rivers. This statement, however, must be received with some qualification, as I have seen the first and second in a dying state, and feel very doubtful about the third. Had the assertion been confirmed, it might have been worth while to have double budded the mussel, using one of these varieties for the first working. Affected trees have been headed down and successfully worked with certain varieties of plums when the decay has not been too far advanced; time is required to prove the permanence of the scion, Should present expectations be realised, wo shall hay 6 one of the most striking instances of the influence of the scion upon the stock that has yet been brought forward. lam assured, however, that some varieties of plums do not succeed under such conditions. Une instance in which the process of exhaustion appeared to be retarded by remedial measures came under my notice at the Bay of Islands, Mr Goodhue, nurseryman, of Taumarere, washes or syringes all his fruit trees during the winter season with a mixture of lime, sulphur, and carbolic acid, in the following proportionstwo gallons unslaked lime,'lib sulphur, |lb Calvert's carbolic aoid powder. Sufficient water is put upon the lime to slake it; the sulphur and carbolic powder are then added and well incorporated. It can either be used dry as a fine powder to dust affected trees, or by the addition of water can be made into a wash of any required consistency, Mr Goodhue's fruit-trees were remarkably free from insect-pests; in every case the bark was bright and clean, and the trees generally ,vero in a vigorous state of growth. All his peaches, however, showed unmistakable evidence of gradual decay, although he informed me they had greatly improved since he commenced his treatment: the bark looked fresh, and was less shrivelled than usual, but the presence ' of dead shoots, with occasional gilinniy exudations, told its own tale. Unquestionably the application of the wash had proved beneficial in destroying all insects, and thus lessening the strain upon the vital energies of the plant. Curl or Blister {Taphria deformans). —This well-known pest is a troublesome enemy to the peach-grower, and is one of the first parasites to make its appearance on trees affected bypeach-blight. Although commonly considered to be caused by insects, it is in reality a fungus of a very simple structure, but remarkable for its effect upon the leaves, which are ounously contorted and curled, often presenting the appearance of being covered with whitish blisters. The fungus consists of a thin layer of cells developed on the surface of the leaf, and containing sporida, which causes the leaves to look as if they were dusted with flour. The best remedy is to dust the leaves with sulphur. Mr Goodhue's mixture would, doubtless, prove beneficial. Other species of fungi are found on the leaves of the peach, but at present little is known about them.

Peach-aphis (Aphis amygdali).—Two or more species of aphis are found on the peach, but the form "lost freqqoiitjy observed appears to bo identical with the common peach-aphis of Europe. The aphis frequently appears on the peach in great abundance, and acoelerates the process of exhaustion caused by peaoh-blight, of which it is not unfrequently said to be the cause. It is readily destroyed by syringing with soapsuds, tobacco-water, or with soft soap dissolved in hot water; or the leaves may be dusted with lime or sulphur, Heavy rain will often clean trees badly infested with aphides,