APPLE DISEASES 123 



portions on the branches suffer most because they are exposed 

 to extremes of temperature. Likewise apples on the south or 

 southwest sides of trees are always most affected. (3) Defolia- 

 tion or reduced foliage-area. Should a tree be defoliated by 

 some pathogene or other cause shortly before the ripening-period, 

 the fruit is likely to suffer from water-core. The decrease in the 

 foliage-area results in reduction of the evaporating surface, 

 consequently an excess of water is liable to accumulate. Severe 

 pruning may also act detrimentally in this way. The removal 

 of a large number of branches means the reduction in the num- 

 ber of leaves, and therefore checked transpiration. Any injury 

 to the foliage, but which at the same time does not cause de- 

 foliation, tends to have the same effect with respect to water- 

 core. (4) Excess tension set up in the cell as a result of a rapid 

 ripening process. In ripening, the starch is converted into 

 sugar ; water is absorbed by the sugar and there results a high 

 pressure tending to force water into the intercellular spaces. 



Control of water-core. 



It seems to be out of the question to wholly prevent water- 

 core, since certain climatological factors are so intimately in- 

 volved. Some authorities say that it is absent where the soil is 

 well managed throughout the year ; that it is absent in soil of a 

 loose texture ; and that adequately drained soil seldom produces 

 glassiness in fruit. Further observations along these lines are 

 necessary before positive conclusions can be reached. The 

 conditions already enumerated under which water-core has 

 been observed may offer some suggestions as to remedial meas- 

 ures, although prevention or cure are as yet little short of 

 impossible. Among those recommendations worthy of note 

 are : (1) In thinning the crop those fruits nearest the tip of 

 the branches should be removed, especially in cases where pref- 

 erence is not otherwise to be shown. (2) Cultivation should 

 proceed normally, and a cover-crop should be planted at least 

 as early "as the middle of July to remove excess moisture. 



