78 BITTER PIT INVESTIGATION. 



of the soil for holding moisture, and by forming a soil mulch wasteful evaporation from the soil is 

 checked, so that the roots of the tree have a more regular and constant supply of moisture ; and as a 

 consequence there is a more regular and constant transpiration from the leaves and fruit. If the 

 transpiration is properly regulated there is less liability to Pit. 



The influence of the stock on the development of Pit has not yet been experimentally determined. 

 The Northern Spy stock, so generally used for budding or grafting as it is thoroughly proof against 

 the attacks of Woolly Aphis at the roots and produces a dense mass of fibrous roots, has a beneficial 

 effect on the transpiration of the variety grafted on to it. 



In the stock test being conducted at Burnley Horticultural Gardens, while the varieties on other 

 stocks required artificial watering, the same varieties growing alongside on Spy stocks did not 

 require it. 



It may be stated generally that for the prevention of Bitter Pit the most up-to-date treatment 

 of the tree and the soil must be followed. Excess has to be avoided and moderation practised in the 

 various orchard operations such as pruning, manuring, and irrigation, so as to maintain as uniformly 

 even conditions as possible. The injudicious application of water after a dry spell may result in 

 Bitter Pit. Uniform moisture conditions are of prime importance, and the practice of cultivating 

 after rain so as to prevent the moisture rapidly evaporating has much to recommend it. 



There is one final method of preventing Bitter Pit which must never be lost sight of, although 

 it is a slow process, and that is the breeding of Pit-proof varieties, breeding the disease out, instead of 

 "dodging" it as we are trying to do by our present methods. This would be a work of time, of patience, 

 and of skill, but while we are breeding wheats, for instance, to suit our conditions and be rust-resisting, 

 I do not see why a Federal Bureau of Agriculture should not encourage the breeding of fruit trees, 

 in connection with which the susceptibility to Bitter Pit would be one of the factors considered. 



XVII. PRACTICAL APPLICATIONS. 



As a result of the experimental tests and the knowledge we now possess of the wonderful 

 structure of the fruit, with its intricate network of vessels permeating among the pulp-cells in every 

 direction, it is possible to suggest such measures as will ensure oversea shipments arriving in a perfect 

 condition. Also such practical operations in the orchard as will reduce to a minimum the liability 

 to Pit while the fruit is still growing and maturing on the tree. 



1. In picking and packing apples they should be handled as carefully as eggs, since the 



delicate network of vessels immediately beneath the skin is easily ruptured, and the 

 slightest bruise produces a flaw in the flesh. 



2. Do not allow trees to bear too early, since the practice not only tends to weaken the tree, 



but the very rank growth of fruit on a quite young tree bearing only a few apples is 

 very liable to Pit. Rapid growth is always accompanied by excessive transpiration, 

 and the ebb and flow from rapid to slow growth are the most favourable conditions 

 for the disease. 



3. Since the respiration of the apple is slowed down at 32 degrees Fahr., and the fruit is in a 



state of suspended animation, the development of Bitter Pit is retarded. For a 

 similar reason the ripening process is arrested, and if the fruit is shipped on the green 

 side or just as it is beginning to turn to the ripening stage, and kept at this 

 temperature in an atmosphere necessarily dry, it will reach its destination without 

 any danger of becoming over-ripe. It is not sufficiently recognized that the apple 

 continues to breathe for a considerable time after it is picked, since it is a common 

 delusion that only animals respire. 



