- 2 



4. (cont) Furthermore, obtaining sufficient red color on 

 the newer strains of 'Delicious' is not a problem. 



Suggested rates of actual N for bearing apple orchards, based 

 on potential yield of trees are as follows: (a) less than 15 bu- 

 shels (bu): 0.66 lbs.; (b) 15 to 25 bu: 0.66 to 1.00 lbs; (c) 

 more than 25 bu: 1,33 to 2.00 lbs. These suggested amounts are 

 for hand applications under the spread of the branches. When the 

 materials are broadcast over the entire orchard floor, it may be 

 necessary to increase the rate of application in order to obtain 

 the same tree response as with hand applications. 



Calcium (Ca): Ca in 'Mcintosh' and 'Delicious' leaves in 1972 

 averaged 0.80% and 0.71%, respectively, which is considerably less 

 than the desirable content of 1.25-1.50%. 



The incidence of cork spot and bitter pit in apples is known 

 to increase as the calcium level in leaves and fruit declines. 

 Furthermore, recent data show that fruits with low Ca content de- 

 velop more internal breakdown and decay in storage than those with 

 a high Ca level. 



It is MQvy difficult to increase Ca content of apple trees and 

 fruits. Although foliar sprays of Ca solutions have been shown to 

 reduce bitter pit, they have not eliminated it. A major problem 

 is the Mery poor absorption of applied Ca into apple trees and fruits 

 Furthermore, Ca in the soil moves yery slowly in the tree and most 

 of it is quickly tied up in insoluble form. However, we suggest 

 the following measures to increase Ca content of apple leaves and 

 fruits. How far these treatments will go in developing adequate 

 Ca levels, or how long it will take to reach adequate levels, is 

 not known. 



Continue to apply 3 tons of limestone per acre every 2 

 to 3 years. Where high magnesium lime was used in the 

 last application, the use of a more soluble high Ca lime 

 will act more rapidly and will provide more Ca. 



Change from ammonium nitrate or urea sources of fertilizer 

 N to calcium nitrate. Calcium nitrate fertilizer quickly 

 increases the level of soluble soil Ca, increases the 

 downward movement of Ca and raises the pH of the soil. 



Apply 3 to 5 calcium sprays at 10-day intervals, starting 

 2 weeks after petal-fall. We suggest using calcium ni- 

 trate (fertilizer or technical grade) at the rate of 5 lbs 

 per 100 gallons of water. A spreader or wetting agent, 

 such as Triton B, should be used at the rate of 3 fluid 

 ounces per 100 gallons of water. 



Calcium nitrate may stimulate shoot growth which will com- 

 pete with the transport of Ca into the fruit. Calcium 



