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BITTER PIT INVESTIGATION. 



Mr. A. H. Benson, Director of Agriculture, Tasmania, conceived the happy idea of sending 

 out a few practical questions concerning Bitter Pit, principally to the various Fruit Boards. Nine 

 of them replied, and their answers are incorporated in the general analysis, but the results may 

 be briefly stated. 



If we eliminate the points on which there is difference of opinion, it is generally agreed that 

 the principal varieties liable to Bitter Pit in Tasmania are — Cleopatra, or New York Pippin, 

 Sturmer Pippin, Ribston Pippin, Scarlet Pearmain, Adams' Pearmain, and French Crab ; that 

 young and vigorous trees show it most ; that the retention of the lateral branches, when pruning, 

 tend to diminish the disease ; and that the weather conditions most favorable to Pit are a wet 

 summer, or heavy rain after a dry spell 



XVIII— VARIOUS CAUSES ASSIGNED FOR BITTER PIT. 



Almost every conceivable cause has been brought forward to account for this disease. It 

 has been attributed to a mechanical injury, brought about by blown sand, to rapid evaporation 

 of water from the surface of the fruit, to spraying with poisonous compounds, to insects, such as 

 the Harlequin Fruit Bug or mosquitoes, to faulty or heavy pruning, to excessive or deficient 

 manuring, to unsuitable stocks, to climatic conditions, to sudden change of temperature, to 

 defective drainage, to irrigation, to overgrowth, to a spell of dry weather followed by a heavy 

 rainfall, to bursting of sap cells, so that the sap escapes and oxidizes, to some natural tendency in 

 the varieties affected, and, lastly, to fungi or bacteria. 



These are all theories offered by fruit-growers and others, sometimes singly^ and sometimes 

 in combination, and they are being put to the test, in so far as they are likely to throw any light on 

 the subject. 



They may be briefly considered under a few general headings, so as to eliminate the unfit, 

 and retain whatever may be thought worthy of further trial. In all these theories it will be 

 observed that there is no reference to the structure and functions of the fruit concerned, and it 

 is a fundamental principle of pathology, whether of animal or plant, that, in order to understand 

 the abnormal or diseased, it is necessary to be acquainted with the normal, so that the consideration 

 of the problem, in the light of what has already been stated as to the conditions and results of the 

 ordinary vital activities of the apple and pear, may give a new turn to our ideas of the causes 

 producing the symptoms of Bitter Pit. 



The effects of manuring, pruning, stocks, irrigation, and different methods of cultivation, 

 are being tested in an experimental way, and will be dealt with under their respective headings, 

 and the following agencies will now be considered in so far as they influence the disease known as 

 Bitter Pit :— 



1. Mechanical agencies. 



2. Unfavorable conditions of soil and climate (including heat and moisture). 



3. Insects. 



4. Fungi and Bacteria. 



MECHANICAL AGENCIES. 

 The idea of blown sand causing mechanical injury to the fruit was suggested at the Cape, 

 but this would evidently only cause mechanical injury, similar to that of the impinging of 

 hail-stones, which has already been considered. It does not account for the deep-seated injury 

 to the cells of the flesh, which in the case of Bitter Pifr is known to arise from internal causes, and 

 the exterior "pitting" is a consequence of that internal injury. 



