95 



logical disease. The prevailing opinion of those who have 

 studied the disease is that it is caused by disturbed water re- 

 lations. Seasonal conditions, such as frequent winds accom- 

 panying low humidity, high temperatures and bright sunlight, 

 Avhich promote loss of water by transpiration, may be factors. 

 Sudden or fluctuating changes in temperature and alternating 

 wet and dry periods during the latter part of the growing 

 season seem to favor development of the disease. 



Bitter-pit may appear on the fruit after it is half grown, 

 but it is seldom noticed by the orchardist until the fruit is 

 nearly mature. The first outward sign of the disease is when 

 slightly sunken spots appear scattered over the surface of the 

 fruit, usually most numerous near the calyx end. They are 

 nearly round, seldom over an eighth to a quarter of an inch 

 in diameter, and might be taken for hail bruises. (Fig. 9.) 

 They increase in number as the fruit matures. With age, they 

 become brown in color and deeper, but the skin covering them 

 does not rupture. The flesh beneath each spot is brown, dry 

 and corky. Brown streaks or spots of corky tissue, not con- 

 nected with surface spots, extend through the flesh. Affected 

 fruit is usually somewhat bitter to the taste. 



Bitter-pit is often mistaken for fruit-spot. The spots of 

 this disease are, however, usually larger, more uniformly round 

 and deeper than those of fruit-spot and the discolored, corky 

 streaks extend deeper into the flesh. 



The disease may continue to develop in storage, but this is 

 preventable through control of temperature and ventilation. 

 Fruit affected with bitter-pit should be stored at a uniform 

 temperature between 30 and 33 degrees F. Higher temperatures 

 permit development of the spots. 



Bitter-pit cannot be controlled by spraying, although the 

 maintenance of a healtjhy leaf growth by keeping other dis- 

 eases in check is probably beneficial in reducing the amount of 

 this trouble. There is, in fact, no definitely known method of 

 control for the disease. Certain orchard practices, however, 

 tend to reduce it to a minimum. Judicious pruning, to keep 

 the set of fruit evenly distributed on laterals, and good soil 

 drainage are among the most important things to consider. 

 Usually there is less of the disease on apples borne on laterals 



