CAWTHRON INSTITUTE BULLETIN, NO. 1

Nelson Evening Mail, Volume LXVI, 28 April 1934, Page 3

CAWTHRON INSTITUTE BULLETIN, NO. 1

WATER-DEFICIENCY DISEASES OF APPLES

“INTERNAL CORK,” “CRINKLE,” AND “DROUGHT SPOT”

(By Theodore Kigg,.M.A., M.S.c., F.1.C., F.X.Z. Inst., Director of Cuwtliron Institute)

INTRODUCTION

trees in treated and cultivated areas of the orchard. CAUSES OF THE DISEASES All investigators who have studied these diseases agree that they result from water deficiencies in the fruit. It is considered that the transpiration of moisture from leaves of the trees during periods of low humidity and bright sunlight accompanied by dry soil conditions robs the developing fruit, resulting thereby in the death of apple cells located either within the core line or in the flesh of the apple. The work of Mix and Chandler in the United States of America has shown that tlie osmotic pressure of the sap of the leaves is much higher than that of the fruit, causing in times of waterdeficiency a withdrawal of moisture from the developing fruits to the leaves. Came, of Australia, is of the opinion that the high sap concentration pro-, duced in the developing apples as the result of the withdrawal of moisture by tiie leaves, is the prime cause of tin* death of apple cells. No experimental proof has yet been obtained of the exact cause of cell death, whether through nigh sail concentration, hvdrolisation of starch accompanied by subsequent guttatioii of cells with sap. or through poisoning of cells by carbon dioxide in the tissue of the apple.

During the last ten years, considerable loss lias been occasioned oreliardists located in ditlerent parts of the Nelson apple lands, through the occurrence of certain water deficiency diseases of apples known under the names of “internal cork,” “crinkle,” and “drought spot.” In certain years, particularly those of the 1923-24, 1925-20, and during the last three seasons, the loss suffered by growers has been serious and in affected orchards many hundred cases of fruit have been left on tin: trees or discarded as unsaleable. Since the publication of observations made by officers of the C'awthron Institute in connection with the occurrence of these diseases during the 1925-20 season in Xelson, information has become available concerning widespread damage caused bv similar ailments iu both British Columbia and Australia. It is dear from the investigations undertaken in these countries that the presence of these ailments in the Xelson district is not peculiar to our own industry but is characteristic of apple culture on certain types of soil and under particular climatic conditions in different parts of the world.

DESCRIPTION OF THE AILMEXTS

The three apple diseases grouped under the title of water-deficiency ailments may he briefly described as follows: — (a) “internal Cork.” Superficially the apples appear sound and in many eases no external evidence is visible of damage in the apple llesli. On cutting open the apples, browning of the tissue within the core line is characteristic of certain varieties, while in others there may he not only browning of the tissue surrounding the core, I'mt brown corky areas in the llesli of the apple may also he present. (h) “Crinkle.” In the case of “crinkle” the surface of the apple is corrugated, and .this is accompanied by deep-seated injury to cells in the flesh of the apple. Owing to the death of a comparatively large number of cells irregularity in the development of the apple takes place, resulting in malformation. (d) “Drought spot.” Tu the case of drought spot, which is frequently seen in the Stunner variety, small hemispherical depressions occur on the developing fruit, which in the early stages are characterised by the. presence of drops of gummy exudate from the affected cells. Damage in such cases is confined to cells located in the epidermal or sub-epidermal layers of the fruit. In the case of the three ailments mentioned above, damage appeals in tin early stage of fruit development, particularly during Xovember ! and December.

PREVENTIVE MEASURES

The investigation of water-deficiency ailments of apples is but yet in its preliminary stage, and much work remains to be (Tone before the exact factors determining the incidence of these ailments are clearlv understood. The observations made by McLarty in British Columbia concerning the association of serious trouble with injury to the root-system of the tree in a previous season, either by prolonged drought or by water-logging of the soil, warrant careful study to see if a similar association prevails on Nelson soils. The possibility of high transpiration from the foliage of orchards affected with trouble being associated with low mineral supply in the tree is likewise a question which should receive careful examination. In British Columbia, McLarty has shown that irrigation during those times when water-deficiency in the'tree is likely to occur has resulted in a great reduction of the ailments. Small experiments carried out by a Nelson orehardist appear to confirm this work •of McLarty, supporting thereby the general conclusions arrived at by a number of investigators that the ailments are definitely water-deficiency troubles. In many Nelson orchards irrigation is obviously impossible, but @qmc alleviation might in certain eases he obtained through greater care in cultivation and the production of a; good tilth early in the season. i Grout care .should be exercised in the use of orchard implements to avoid severe cutting of tree roots by the plough or by heavy discs. In a similar way attention should be paid to avoid exposure of any portion of the root- ! system to sun or drying winds. In those orchards where erosion is bad, ploughing on to the trees might he recommended so iis to ensure a good cover over roots which lie close to the surface. i The association of severe damage with liberal nitrogenous manuring of trees in British Columbia is in keeping with our knowledge of the causes underlying the production of waterdeficiency ailments of apples and confirms the recommendation made by officers of the. Institute several years ago concerning the advisability of greatly reducing or eliminating nitrogenous manuring in those parts of the orchard where .serious loss has been experienced. In view of the fact that these wnterdefieieiicy ailments result from the failure of the root-system of the trees , to supply the full moisture requirements of both fruit and foliage, it would seem possible that a drastic thinning-out of affected trees —thereby greatly reducing leaf area in relation to root-system —would prove beneficial in lessening the amount of damage. Another line of research which is worthy of close examination is the cutting-back of badly affected varieties and their grafting to those which have greater powers of resistance. During the present season Dunn's Favourite, Stunner. Jonathan, Pioneer, Premier, Granny Smith, Gravenstein and Statesman liave all been badly affected. The Delicious and Tftsma varieties have shown only moderate to slight damage. So far little damage has been found in the Dougherty variety, but it must he admitted that few observations of this variety on land subject to water-deficiency ailments have been possible. The known resistance of the Dougherty variety to other physiological diseases suggests, however, that it may possess a certain degree of immunity from water-deficiency ailments and would he worth while testing on typical areas where much damage in other varieties has been experienced. Another aspect of the problem which requires consideration is the influence of root-stocks on the incidence of these ailments. It has been noted that welldeveloped vigorous trees are more prone to these ailments than those of less vigour. The experiments of the Institute have shown that the use of seedling and double vigour stocks produces greater tree development than is the ease with corresponding trees on the Northern Spy stock. These facts suggest that trees on the more vigorous stocks will he more prone to waterdeficiency ailments than those of the less vigorous Northern Spy stock. ~ DO THEY KNOW WITAT THEYWANT? Difficulties occurred when the producers were ready to start work 'on a certain picture in England. Trouble occurred because at the last moment Miss Dili Dninita did not like her comedy part. No one had any idea of this until she arrived from Paris and said she wanted to play the part of the Queen because she now regarded herself as a dramatic actress, and no longer a comedy actress. If we were faced with an equally difficult situation, we should no doubt first of all pull out our pipes and light up. The measure of help and encouragement yon can expect from your pipe, however, must depend upon the Tobacco with which yon fill it. You will find there is nothing so altogether satisfying and refreshing as Red Shield Dark and Blue Shield Medium. They are New Zealand Tobaccos at their host—and toasted to a turn. Both obtainable in handy 2oz. pocket tins, 1/7 —and one-pound canisters. *

EFFECT OF CLIMATIC FACTORS

In the Nelson district severe damage lias been noted in those seasons where particularly low rainfall lias been) experienced during the mouths of Xovember and December. Low rainfall in the Xelson district is invariably associated with bright sunshine, low humidity and frequently during the months of November and December, with strong south-west winds of great drying power. Although the incidence of great damage lias been found to be associated with low rainfall during the months of November and December, it \u impossible to state to what extent the incidence of the ailment is affected by low humidity,.strong winds and bright sunshine. In all probability al! these climatic factors are important in the production of these ailments.

EFFECT OF SOIL TYPE

From examinations made in the Xelson district it is clear that curtain soil types are more frequently associated with these ailments than others. Little trouble, it' any, has been experienced on either the’ light gravelly soils of Stoke and Hope, or on the heavier alluvial loams of Stoke and Lower Moutcrc. The deep sandy silts of Kiwaku and Umukuri are likewise not associated with any serious loss from these ailments. Somewhat abnormal locations on the Moutere Hills type of soil, and also on soils derived mainly from granite wash, have been found most definitely associated with the incidence of these ailments. In a number of cases examined, it has been found that affected orchards have been planted on a somewhat shallow soil underlaid by heavy elav or hard pan which prevents free root-development of the trees! In other cases a coarse gritty layer lias been noted underlying a loamy surface, likewise in all probability reacting unfavourably on root development. In other cases, damage has been associated with trees where there is great fluctuation ill the winter and slimmer water-level in the soils. Soils with had textural properties—liable to cake badly—have been found associated with these ailments, both in British Columbia and in Nelson..

EFFECT OF CULTIVATION

In the examinations made by the Cawthron Institute in previous years, poor cultivation and had management of orchard soils was found to affect considerably the severity of the ailment. fn those eases where orchards had been ploughed and left rough so that tlu‘ surface dried out badly,.or where damage was done in ploughing through cutting of the roots, or where portions of the root system were left exposed to sun and wind, greater damage occurred. The disorders were less serious where a good tilth had been obtained early in the season, and "'here care had been taken not to cut the roots with either plough or heavy discs. EFFECT OF MANORIAL TREATMENT . Tu British Columbia the investigations of McLarty have shown that heavy nitrogenous manuring, favouring luxuriant, foliage development, is accompanied by greater incidence of these ailments, hi the Nelson district, although no exact experiments have been conducted it has been noted that trees with luxuriant foliage development arc subject to more severe trouble than neighbouring trees with inferior foliage. Furthermore, trees in grass where the nitrogen level is likely to he low, appear to he less susceptible. to these ailments than corresponding Economise on that rein dy for your cold Buy “NAZOL.” Gives instant relief. Costs only 1/3 for a bottle containing 60 doses. Larger size 2/6 contains 120 doses.