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Sturmer : N trees produced 36 lb., or 26 per cent., more, PN trees produced 95 lb., or 76 per cent.) more, and PNI? trees produced 1131b., or 83 per cent., more than the untreated controls. Phosphate by itself has not yet given an increase of statistical significance. (b) Short-term Manurial Investigations.—Miscellaneous experiments on various aspects of manuring are briefly summarized as follows : Dunn's Favourite trees receiving lime in addition to PNK produced 78 lb., or 23 per cent., more than unlimed trees. On Jonathan trees receiving P and K, 2 lb. ammonium sulphate increased the yield by 861b., or 53 per cent., as compared with no-nitrogen trees, and 41b. increased the yield by 1271b., or 79 per cent. The 01b. and 21b. trees gave approximately equal weights of Fancy-grade fruit, but the i lb. trees yielded about 22 per cent, less of this grade. Variations in the time or method of surface application of ammonium sulphate have again been without effect on tree or crop. With Dunn's Favourite, 2 lb. and 41b. ammonium sulphate per tree increased yields by 74 lb., or 44 per cent., and 165 lb., or 99 per cent., respectively, as compared with the controls receiving no nitrogen. No differences of any kind have been observed between the results obtained with sulphate of ammonia and dried blood as sources of nitrogen. Potash has continued to give improvement in yield and colouring of the Jonathan variety. (c) Rootstock Trials.— The trees in these tests at Appleby are now ten years old from date of planting as yearling rods, and substantial crops are now being produced by most trees. It is apparent that the effect of a given rootstock may vary according to the scion variety worked on to it, although the results noted below are not to be regarded as indicative of the relative positions that may be ultimately attained. With Cox's Orange Pippin and Granny Smith the yields on Mailing I and Northern Spy stocks are at present two to three times those on M XII and MXV stocks. With Jonathan, MI, M XII, and Northern Spy are very close together in yield, but MXV is distinctly lower. With Delicious, on the other hand, M XII is at present very much below MXV in yield. Northern Spy is not significantly higher in yield than M XV, although both Spy and M I are very significantly higher than M XIL (d) Varietal Trials.—The existing collection comprising coloured strains of popular apple varieties has been added to by the taking-over of budwood material of a considerable number of crosses made by a North Island orchardist. These are to be fruited to determine whether they have any market potentiality. (e) Spraying Trials. —These form part of the work controlled by the Plant Diseases Division, and the results are incorporated in the appropriate sections of the fruit report of that Division below. Plant Diseases Division, Auckland I. Pomology (a) Rootstocks. —(i) Apple : Growth and yield trials of the varieties Sturmer, Jonathan, Cox's Orange, and Dougherty on a wide range of rootstocks have been continued. Of four woolly-aphis-resistant stocks under test, Merton 779 has produced larger trees than has Northern Spy, with Dougherty as the scion. East Mailing XII has again maintained its position as the most vigorous stock, irrespective of scion variety. As fruit-picking is not completed, crop comparisons for the year are not available. (ii) Citrus : Rootstock influence on growth and flowering of three-year-old Washington Navel trees on sweet orange, sour orange, citronelle, and Poncirus trifoliata, and on various combinations of these stocks, is now very marked. Sour orange has in every instance induced stunted growth accompanied by severe chlorosis and profuse flowering, and is obviously incompatible with this scion variety. P. trifoliata has hastened flower-formation, while citronelle and sweet-orange stocks have produced the largest trees. (b) Varieties: (i) Apple: Of new varieties undergoing trial, Laxton's Exquisite, Laxton's Fortune, and Ellison's Orange are promising early dessert varieties to precede Cox's Orange. Monarch is the most noteworthy of the culinary varieties, being a prolific bearer maturing in January. (ii) Peach : Twelve new varieties have, during their five years of growth, shown almost complete immunity to leaf-curl. Similar features of tree habit, foliage, and fruit are common to all, separating them as a group from the other ninety varieties being grown at the Division's headquarters at Owairaka. During the year descriptions were completed of the fruits from seventy-five varieties, the purpose being to ascertain the standard type for each. (iii) Citrus : The most promising of the many new varieties under trial are Kara mandarin, several tangelos, and the grapefruit, Wheeny. The latter is of exceptional quality, maturing later than the New Zealand grapefruit. (c) Miscellaneous. —New Zealand Fruitgrowers' Federation Nursery : Work of provincial budselection committees has been supervised, additional to activities at the nursery. A further supply of some hundreds of apple stocks was forwarded to the nursery during the year. 11. Plant Diseases Investigations (a) Therapeulant Testing.—(i) D.D.T. : Small-scale trials have indicated the value of this and insecticides of similar composition. Control of grass-grub beetles on fruit-tree foliage was secured with a 005 per cent, concentration without leaf injury, whereas 1-6 per cent, lead arsenate was largely ineffectual. Comparable control of carrot aphides was secured with 0-1 per cent. D.D.T. and nicotine sulphate 1-500. Used as dusts (1 per cent, and 2 per cent.) and sprays (o'os per cent, and 0-1 per cent.) the product gave excellent control of both white butterfly and diamond-back moth on cabbages. On apple-trees good control of codling-moth was secured with 0-05 and 0-1 per cent, sprays, results being superior to those secured with standard lead-arsenate sprays of 0-15 per cent. D.D.T. proved ineffectual against red-mite when applied to apple-trees, the mite population increasing considerably over those on check trees, the increase being apparently caused by killing of predaceous insects which assist in holding red-mite in check. (ii) Fermate : Encouraging results in control of black-spot of apples was secured with Fermate, a new fungicide with the composition ferric dimethyl-dithio-carbamate which may be used as a substitute for sulphur and polysulphide sprays.

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