SO.MK OF Oil: MOST COMMO.X Ai'i-u-: I )ISKASKS 



If the fruit be cut open, the flesh under the pit is found to be 

 dead, brown, dry and spongy, and extending in toward the core 

 for only a short distance. Sintered throughout the flesh are 

 brown spots, which have no direct connection with the .surface 

 spots. 



As previously noted, the cause of this peculiar trouble is not 

 fully understood, it has been satisfactorily demonstrated, how- 

 ever, that stippin is not a mechanical injury, nor is it due to the 

 action of any bacteria, fungi or insects. The common opinion of 

 those who have investigated the disease more carefully is that the 

 injury results from abnormal distribution of water through the 

 fruit. As to the nature of this abnormal distribution, authori- 

 ties are not wholly agreed. Therefore, the main theories as to 

 the manner in which poor distribution of water may bring about 

 the disease should be noted; there are four: 



1. The injury results from an extremely rapid transpiration or 

 loss of water from the cells, thus bringing about a concentration 

 (f the sap and the hi ling of those cells nearest the sap tubes. 



2. The spots result from the death of groups of cells because 

 dryness of the soil early in the growing season prevents the trans- 

 [ortation of mineral matter (food) to these cells; hence they 

 starve and die. 



3. The injury occurs under such conditions as prevail when 

 the transpiration of the apple is rapid during dry warm days, and 

 the process of evaporation is suddenly stopped during cool nights. 

 Under such conditions, the roots in the warm soil continue to 

 force water into the cells of the fruit at night. Hence, cells near 

 the source of the supply, becoming gorged and distended, finally 

 burst and die. Adjacent cells, being deprived of their water 

 supply from such cells, also die. 



4. The brown spots result from a death of cells due to a de- 

 ficiency in the water supply. This deficiency in a wet season 

 results for the reason that the apple grows very rapidly and the 

 conductive system of the apple is not able to supply the new 

 growth ; hence the water is deficient. In a dry season, the trans- 

 piration (evaporation) is excessive ,and, as the soil lacks moisture, 

 it cannot supply a sufficient amount of water, again resulting in 

 a deficiency. 



