-3- 



Although yield per tree favored the more productive standard- 

 type strains in 1971 and 1972, higher tree numbers per acre are 

 possible with spur trees. Actual spacing trials provide the most 

 reliable estimate of yield per acre. In absence of these, we 

 arrived at theoretical tree spacings for the strains by using tree 

 spread in 1978. Some trees of the standard- type strains have re- 

 quired pruning to keep them in their allotted space; as a result all 

 standard- type strains averaged 19' spread. Tree spread of Sturdee- 

 spur and Starkrimson averaged 15' and 14', respectively. 



Theoretical yields per acre were determined by multiplying 

 average yield per tree by trees per acre. The theoretical yields 

 showed that Sturdeespur was more productive in 1970 and that there 

 was no difference in productivity between standard-type and spur- 

 type trees in 1971. In 1972, Turner Red was as productive as Sturdee- 

 spur and Starkrimson. Thus, in this study yields per acre in the 

 early fruiting years favored neither the standard nor spur-type strains 



Yields from 1970 through 1978 : Cumulative yields per tree and 

 per acre the first 9 years showed that Turner Red was more productive 

 than some of the other standard- type strains. However, the producti- 

 vity of Red Prince, Rogers Red, Richared, Gardner Red, and Royal Red, 

 which are planted in orchards in eastern United States, was comparable. 



The trees of the spur-type strains are smaller than those of 

 the standard- type strains, but production per tree of Sturdeespur, 

 Red Prince, Jardine Red, Richared and Rogers Red was similar. Sturdee- 

 spur had the highest production efficiency (production per area 

 occupied) of all strains. 



The cumulative yields per tree indicated that Starkrimson was 

 the least productive of all strains, but when the theoretical yield 

 per acre was calculated it was not, because tlie trees of this strain 

 are small. The theoretical cumulative yield per acre generally was 

 similar for the standard-type and spur- type strains. 



Water Core 



Several indices have been used to estimate maturity of Delicious 

 strains. We chose water core because it is of annual concern and 

 a reliable index of maturity under our conditions. Water core is 

 associated with mature and over-mature Delicious fruits. Fruits with 

 this disorder may fail to meet U.S. Standards for Extra Fancy fruit 

 and severely affected apples often develop internal breakdown during 

 storage. 



In this study, Starkrimson fruits have had less water core than 

 other strains. Nevertheless, the percentage of Starkrimson fruits 

 with water core classified as medium and severe was not consistently 

 less than in the other strains. Since water core can develop rapidly, 

 this difference in water core susceptibility may be of little practical 

 significance in some years. 



