The Orchard.

New Zealand Mail, Issue 996, 3 April 1891, Page 23

The Orchard.

BITTER-ROT IN APPLES. Mr Sydney Smith, Minister of Mines and Agriculture (says the Sydney Morning Herald) ha 3 received a report from the pathologist of the Department of Agriculture on the disease known as the bitter-rot of the apple (Gloeosporinm versicolor), which does not, however, attack all varieties of the apple, certain sorts being comparatively free, and others again being so subject to it that the entire crop is uniformly a failure. It has also been observed to occar naturally on the peach, and can be easily propagated on other fruits. This ha 3 been done by thr ’sting a sterilised needle bearing a few bitterrot spores through the skin of a peach, plum, nectarine and cherry ; from the puncture thus made a diseased spot appeared after five days, which passed through all the stages which occur in the case of the apple. ThU disease appears on the apple about the time the fruit commences to ripen, the first symptom being a small oircular brown spot on the surface, which rapidly enlarges and assumes various shades of brown, the different shades appearing in concentric rings. After four or five days small pustules, also arranged in concentric rings, appear on the brown spot. When the spot has reached the diameter of a quarter of an inah, the pustules burst and emit a light salmon coloured mass composed entirely of the spore 3of the fungus. The pustules of a single spot at this stage contain several hundred spores, and a little later increase to several millions, for the diseased spot keeps on increasing its size by throwing up ring after ring of pustules until the whole apple beoomes brown and rotten . The entire process requires about a fortnight for completion. The Department of Agriculture has issued a recipe for the treatment of this disease, and it ia as .followslnstead of allowing the diseased fruit to rot on the ground ic should be buried or burnt, as each rotten apple has on its surface several million spores, each capable of generatingjtbe disease and aSecting the crop of the .next year. The pathologist oites the cases of an orchard where the crop uniformly Buccnmbtd to this disease. As the owner allowed the apples to decay under the trees, ‘no as to fertilise the'ground,’ his crop was year after year a total failure. By removing all the rotten apples he found that the disease even in one season was preceptibly decreased. The second season the trees were sprayed with ammonia carbonate of copper three times, at intervals of ten days or two weeks, on all parta of the fruit, especially the blossom end. This will cost with proper apparatus not more than Id for eaoh application, or 3d for the whole season, provided that as many as 100 trees are treated. Ammonic carbonate is made as follows : To one quart of aqua ammonia (22 per cent Banme) add 3oz carbonate of copper, shake until a clear solution is produced, and then dilate with 22 gallons of water. It is hoped that orchardißts will report to the Director of Agricnltare what varieties they find to be most subject to the bitter-rot, for from data thus collected the department hopes to be able to discover the rob proof varieties suitable for oar orchards.