110 



BITTER PIT INVESTIGATION. 



adhering to the apple in which the network is shown (Fig. 90), but in the figure of the apple 

 reproduced direct from the object itself. (Frontispiece). 



There is also a striking confirmation of this in the fact that the same place of origin of the 

 brown spot has been noted by competent observers in Europe, America, and Africa, even 

 although the existence of the network was unknown to them. 



The earliest external appearance of Bitter Pit was noticed when the fruit was about the size 

 of a walnut, but it generally occurs when the fruit is about half grown or approaching maturity. 



It generally occurs in the upper half of the fruit and towards the " eye " end, and this is 

 correlated with the openings in the skin being much more numerous in the upper than in the under 

 portions. Chemical analysis shows that there is less water in the flesh of the upper portion. 



The larger number of openings will necessarily allow more active transpiration to go on at 

 the " eye " end than at the stalk end, and, owing to this extra transpiration, there is less water in 

 the flesh at the top. 



Bitter Pit may be associated with wet or dry seasons, so long as they are intermittent and 

 fluctuating in their character at the critical period of growth. 

 The principal contributing factors to Bitter Pit are : — 



(1) Intermittent weather conditions when the fruit is at a critical period of growth. 



(2) Amount and rapidity of transpiration. 



(3) Sudden checking of the transpiration at night, when the roots are still active owing 



to the heat of the soil. 



(4) Failure of supplies at the periphery of the fruit, followed by spasmodic and irregular 



recovery. 



(5) Inequality of growth, so that the vascular network controlling the distribution of 



nutritive material is not regularly formed. 



(6) Fluctuations of temperature when fruit is in store ; and 



(7) Nature of variety. 



The weather cannot be controlled (except in so far as a smoke-blanket is allowed to drift over 

 the orchard on frosty nights), but the soil and the tree and the fruit formed may be controlled to a 

 large extent by cultivation, manuring, including green manuring, irrigation, the stocks used, and the 

 method of pruning. 



The relation of each of these factors to the development of Bitter Pit is being determined by 

 means of experiments. 



Young and vigorous trees making rapid growth may have^ pitted fruit, from the rapid 

 transpiration and excessive growth interfering with the regular development of the vascular network. 



A light crop, with abnormally large fruit, is more liable to pit than a heavy crop of average 

 sized fruit, equally distributed over the tree. 



The apple, pear, and quince are subject to Bitter Pit, but, apart from the larger number of 

 apples and pears grown relatively to the quince, the latter is least liable. The woolly covering of 

 hairs on the fruit reduces transpiration, and the quince is the only one of these three fruits which 

 retains the hairy covering at maturity. 



Certain varieties of apples develop Bitter Pit in store when subjected to a fluctuating 

 temperature and humid conditions. 



When apples, even very susceptible varieties, are kept at a temperature of 30-32° Fahr., the 

 development of Bitter Pit is retarded. 



There is a scientific explanation for this in the fact that there is a lower limit of temperature 

 beyond which respiration is suspended, and this is generally one or two degrees below the freezing 

 point of water. So the apple at this temperature is m a state of suspended animation. 



The delicate structure of the apple and its abundant supply of vessels show the necessity for 

 careful handling and skilful packing for export. 



