into the 

 It seems 

 fruit is 



Table 2. 



growing stem tips 

 probable that one 

 to maintain annual 



at the expense of the developing fruit, 

 way of combatting excessively low Ca in 

 rather than biennial bearing. 



Relationship between peel 

 and total fruit yield per 



Ca content of Baldwin apples 

 tree. 



1971 



1972 



Range, peel 

 Ca (%) 



Avg. yield/tree 

 (bu. boxes) 



Range, peel 

 Ca (%) 



Avg. yield/tree 

 (bu. boxes) 



0350- 

 0501- 

 0601- 

 0701- 

 0801- 



0500 

 0600 

 0700 

 0800 

 0920 



5, 

 12, 

 14. 

 23. 

 19. 



Conclusions drawn from the 1972 experiments with Ca are as 

 f ol 1 ows : 



1. Calcium levels had no effect on time of fruit ripening. 



2. Low Ca in apples led to increased susceptibility to stor- 

 age disorders and rots. 



3. Small crop size decreased the Ca level in the fruit, and 

 large crop size increased fruit Ca. 



An additional observation should be noted. In 1971 and 1972, 

 nearly the same range of Ca levels existed among the trees, 

 although the individual trees changed greatly. However, occurrence 

 of disorders and decay was much less than in 1971, even on the 'i/ery 

 low-Ca fruit. It therefore appears that while low Ca is related 

 to poor "keeping" quality of apples, it is only among several con- 

 tributing factors. In other words, there is much more to "keeping" 

 quality than just Ca. For example, low fruit Ca makes the fruit 

 susceptible to pitting, but some factors, such as moisture stress 

 or high temperture, "triggers" this disorder. This disorder sel- 

 dom occurs in high Ca fruit. 



*************** 



EFFECT OF TWO APPLE VIRUSES ON RESPIRATION AND 

 ON ORGANIC ACID AND SUGAR COMPOSTION OF APPLE FRUITS 



J.S. Makarski and G.N. Agrios 

 Department of Plant Pathology 



Plant viruses are known to reduce 

 of leaves and to at first increase and 



the photosyntheti c ability 

 later decrease the respira- 



