PATHOLOGICAL CONDITIONS 93 



In the pecan there is a related disorder, though its most conspicuous 

 symptom is the appearance of rosetted branches. This is associated with 

 a deficiency of humus as well as an insufficient moisture supply in the soil 

 but destruction of roots through drought or an extreme depletion of the 

 soil moisture are important contributing factors. ^^ 



Bitter-pit. — In bitter-pit "the diseased tissue is dry and spongy, the cells are 

 collapsed but still full of starch, and the cell walls show no sign of thickening or 

 disintegration. . . . The pits are usually associated with the terminal branches 

 of the vascular bundles, and the surface spotting is often accompanied by a 

 browning of the vascular tissue deeper in the fruit, giving the appearance of nu- 

 merous brown spots in the flesh when the apple is cut. . . . 



"The results of the various experiments have been uniformly consistent in 

 showing that heavy irrigation favors the development of bitter-pit. Heavy 

 irrigation throughout the season has given less of the disease than medium irri- 

 gation followed by heavy, and light irrigation throughout the season has resulted 

 in more bitter-pit than heavy irrigation followed bj^ light. Heav"^^ irrigation the 

 first half of the season caused the trees to develop a more luxuriant foliage and 

 probably produced a lower concentration of cell sap in the apples, both of which 

 facts would tend to make the fruit less susceptible to the forcing effects of late 

 irrigation. The amount of irrigation in August and September has apparently 

 largely determined the amount of disease. 



"Sudden changes in the amount of soil water do not appear to have had any 

 effect upon the amount of disease. No evidence has been found that bitter-pit 

 is brought about by a rupture or bursting of the cells. 



"Large apples have been more susceptible to bitter-pit than small ones, but 

 the increase in the disease from heavy irrigation has been almost as great on the 

 small and medium sized fruits as on the large. . . . Apparently apples are not 

 susceptible to bitter-pit merely because they are large, but rather because of 

 conditions that may sometimes accompany an increased growth. 



"The results as a whole point to the harmful effects of heav>^ late irrigation 

 regardless of the size of the fruit. In looking for the final cause of the disease not 

 only the direct growth-forcing effects of the water should be considered but also 

 the effects of the excess water upon the soil flora and soil solutes."" 



Jonathan-spot. — " 'Jonathan-spot' is the term applied to superficial black or 

 brown spots that are especially common on Jonathan apples. ... In the early 

 stages of the disease only the surface color-bearing cells are involved and the 

 spots are seldom more than 2 mm. in diameter, but later the spots may enlarge 

 to a diameter of 3 to 5 mm., become slightly sunken and spread down into the 

 tissue of the apple to a considerable depth. . . . The results of both years 

 gave some evidence that heavy irigation was more favorable to the disease than 

 light irrigation, but there was nothing to indicate that the amount of soil moisture 

 was an important factor in determining the amount of Jonathan spot."^^ 



To what extent these, or similar diseases are to be found in other 

 fruits is unknown. There is reason to beheve, however, that just as some 

 of these diseases of the apple have been dismissed as winter injury or as 



