CAUSE AND CURE

Nelson Evening Mail, Volume LXX, 13 June 1936, Page 6

CAUSE AND CURE

ANOTHER RESEARCH SUCCESS INTERNAL CORK OR CORKY PIT OF APPLES BORON DEFICIENCY

Co-operative investigations of the Department of Scientific and Industrial Research and the Cawthron Institute under the auspices of the Fruit Research Committee have been completely successful in ascertaining the cause of “internal cork’ of apples and of securing a practical remedy for its treatment. The investigations were commenced two seasons ago, at a time when this particular ailment was occasioning severe losses to orchardists in certain parts of the Nelson district. In the first year of the experiments Mr J. D. Atkinson was able to show that injection of certain boron compounds were remarkably beneficial in overcoming the ailment. Dr. .L O. Askew on the chemical ride showed definitely that the ailment of ap lies was associated with low boron content of fruit. In severe cases the boron content was only one quarter of that found in healthy fruit. During the past season the work has proceeded both in the field and in the laboratory, and as a result confirmation nas been obtained of the great value of boron compounds in overcoming this ailment of apples. The investigations show that soil topdressings of borax at the rate of £lb to fib per tree are sufficient to control the incidence of the ailment, and no harmful effects on the tree have resulted from applications of this amount. Soil investigations have shown that the borax penetrates rapidly into the soil and reaches the root zone of the tree within a comparatively short time. A very interesting result has been Obtained in the control of the ailment by the use of borax sprays. Sprays at a concentration of 0.5% borax have given a complete control of the ailment. The chemical analyses show that boron has been taken up by the leaves.and has been passed on to the fruit, raising the boron content to a normal level. Preliminary experiments indicate that the borax can be mixed with lime sulphur sprays without detrimental effects to the foliage of the trees. If this is confirmed by commercial tests next 'season the use of borax sprays' Would appear to be the most economical way of controlling the ailment.'Probably two sprays of borax at a concentration of 0.25%, the first in early November, and the' second three weeks later, should provide ample boron for the needs of the tree and fruit.

Although further work is required in order to determine how long the topdressings of borax are available in overcoming the ailment, it is considered that applications of borax at the rate of fib per tree distributed over a circie with a diameter of 6 to 9 leet can be recommended with confidence. The use of borax, in two sprays during November at a concentration of 0.25% would appear to be equally advantageous in. overcoming the trouble. Investigations have shown that similar ailments occur in Central Otago, and it. would thus,, appear that the investigations 'conducted in' Nelson will have wide application in other parts of New Zealand. The very successful results obtained in these co-operative investigations reveal in a striking manner the value of research in the solution of agricultural problems. Within two years the cause of an obscure ailment has been definitely ascertained and a safe remedy has been found for its control. In addition, it is anticipated that the work done in New Zealand will have a wide application in the control of similar ailments, in other fruitgrowing districts of the world. .Full particulars of the ..Cawthron Institute investigations during the past season are contained in Bulletin 24 appearing on page 3 of this issue.