NO. 9.

New Zealand Mail, Issue 1206, 12 April 1895, Page 7

NO. 9.

APPLE-SGAB. (Fusicladium dendriticum.) Compiled by J. C. Blackmoee. This fungus causes the disease com* monly known as scab. Doubtless every fruitgrower is familiar with the work of this pest. It attacks the leaves and fruit, and frequently the tips of the young shoots. The scabby ppots which occur on the fruit are usually more or less circular, and at first are quite small, but gradually increase in size, and ultimately the fungus in the central part of the spot dies, and the living fungus is only found at the outer edge. The plant-body of this fungus consists of minute branching threads, which are usually colourless. These threads never penetrate deeply, but grow just beneath the epidermis of- the host. They send up an immense number of short, coloured branches, upon the ends of which the spores or reproductive bodies are borne. The spores are dark brown, and vary exceedingly in size and shape. They are usually one-celled, but occasionally are divided by several transverse

partitions. The fungus is found beneath the epidermis of the host, and when it has attained sufl&oient size it ruptures the thin skin which covers it, and the exposed spores and threads form the brown velvety spots described above. p This fungus usually appears early in the spring, soon after the blossoms f all; and the spores are found throughout the summer, and germinate whenever the proper conditions of moisture and temperature are present. The pest is never very active during hot weather ■, but at the approach of cold and damp the spots rapidly increase in size. The fungus usually forms on young fruits during the prevalence of wet, and seemingly this condition of the weather is necessary for the germination of the spores. TREATMENT RECOMMENDED^ Several remedies have been used, with more or less success, to destroy the spores of this fungus:— The kerosene emulsion. Hyposulphate of soda, lib to 10 gallons. "Jjiquid grisson " : Prepared by boiling 61b of sulphur and 31b of lime in 6 gallons of water until the whole is reduced to 2 gallons ; allow to settle, pour off the clear liquid, and bottle until required. Then mix one part of the liquid with 100 gallons of water. Paris green, which is a compound 6f arsenic and copper, is also considered useful if modified with lime. The limewater should be formed by putting from 41b to 81b of thoroughly "slaked lime into 200 gallons of water. The lime must be,

thoroughly soaked,.after which strain, and •idd lib of Paris green. The most effectual means to check this fungus will be found in the treatment and remedies recommended for pear-cracking and leaf-blight, viz., spraying sulphate of copper (Bordeaux ormula) before the buds begin to swell; then again just before the blossom appears, this time using the ammoniacal carbonate of copper solution; again, two or more sprayings, at intervals of about twelve days, especially if Wet weather prevails, or if the disease is of long standing. If desirable to use an insecticide and a fungicide at the same time, as for districts where the codlih>moth is v prevalent, add fib of Paris green to 150 or 200 gallons of Bordeaux mixture.