SPRAYING WITH ARSENATE

Evening Star, Issue 19127, 19 December 1925, Page 2

SPRAYING WITH ARSENATE

AN APPLE PROBLEM THE PRECAUTIONS TAKEN [Per United Press Association.] NELSON, December IS. In reference to the cable message regarding arsenate on apples, Mr C-imp-bell. Director of the 'Horticulture Division who is at present in Nelson, interviewed by a 1 Mail ’ reporter, expressed the opinion that while the information from. Knglaiul must be treated sonously, the trouble existed mainly m regard to American apples. Spraying apples with arsenate of lead had been the jiracticc lor the past twenty years, and for a long period before that laris green, another arsenical spray, had boon used. The cheapness of arsenate in America no doubt led to its lavish use there, and most likely the present trouble was due to the free use of dry arsenate, Quantities of which may have accumulated round the stem. Mr Campbell stated that ho would recommend 11 1 o■ department’s chemists to make exhaustive tests as to the quality of the arsenate apples. The strength used in Now Zealand was one pound of arsenate of lean *to sixty gallons of water. About onethird of the compound was effective arsenate, and, allowing a gallon ol wash to a tree carrying, say, two bushels of fruit (the greatest portion of which would go on to the loliage, some on the trunk and some wasted on the ground), the estimated quantity of arsenate found on apples immediately after spraying was cortaintly not more than onc-tenth of a grain. This quantity was gradually reduced by the wind and by the time the fruit was picked, graded, wrapped, and packed there was no trace of arsenate on the apples. Growers, said Mr Campbell, must carry on spraying operations without consideration of the development that had taken place. They should spray to within’ a fortnight of picking. When being picked the fruit should be wiped, removing any traces of spray remaining. If this were done he did not think any complaints would be made in England about New Zealand apples, but if the crop were to escape the ravages of codlin moth and leaf roller it was absolutely essential to spray the fruit. No substitutes for spraying were known, and spraying must therefore be depended on at present. When interviewed Dr Tilyard, of the Cawthron Institute, remarked that arsenate which was carried on apples to England was all from later sprays; hence in any case sprays put on before January could be continued with safety. If it were necessary to discontinue late spraying for codlin moth and loaf roller this could be done at a slight extra expense by using instead the methods ol trapping worked out by a Colorado entomologist. This experiment had been carried out this season in Stephens’s orchard at Stoke, and the results wore highly encouraging. Last week no lower than ninety-threo codlin moths were caught by fermented apple juice, and sixty-six of these were fertile females full of eggs. Allowing only 200 eggs per female, over 13,000 young I larva; were prevented from emerging by this catch. By using glass jars instead of wide tins much better results could be obtained, and the liquid would not he spilt in the high winds. The indications wore that leaf roller was just as effectively controlled by this method as codlin moth. “ One obvious reflection remains,” added Dr Tilyard. “ The more we can replace sprays by biological methods of control, the better it will bo for the future of the industry.”

[A London cablegram (December 16) stated: After an informal conference between representatives of the National Federation of Fruit Traders and the health officers of the Port of London and the medical staff of the Ministry of Health Dr M'Fadden, of the Ministry, emphatically stated that the Ministy intended to pursue its investigation at the dock's as far a.s possible. On finding even one-hundredth part of a grain of arsenic to the pound of apples it would continue a minute examination, and on finding onc-tenth of a grain per pound it would probably condemn the entire cargo, and not allow re-export, but order the cargo to ho shipped back to the country of origin. Personally, ho would order condemnation whenever tho presence of one-hundredth of a grain was brought to his notice. The utmost the Ministry would do was to extend leniency for the, next five weeks. Tho fruitgrowers would have to find other means of combating pests, as tho Ministry was determined not to allow the, use of poisonous food. Tho federation at a meeting decided that it was useless to approach the Ministry further, but a sub-committee was formed to urge upon all tho High Commissioners and the Agents-Gcneral the necessity of investigating the matter with a view to getting the drastic regultaions modified.]