POLLINATION IN HIGH DENSITY APPLE ORCHARDS^ 



M.D. Levin 

 Entomology Research Division, Agr. Res. Serv., USDA 

 Beltsville, Maryland 



"Most of our information concerning the apicultural aspects 

 of apple pollination has been obtained over the years with stan- 

 dard trees and plantings. Therefore, the recent trend to high 

 density plantings requires us to reevaulate recommendations for 

 supplying optimum pollination. I intend to discuss the factors 

 affecting pollination and to point out those that are more criti- 

 cal in high density plantings. However, much of what we now know 

 about pollination is as valid for high density plantings as it is 

 for standard orchards. For example, our basic knowledge about ap- 

 ple trees and our understanding of the concept of compatibility 

 are still pertinent. Our definitions of the various terms are the 

 same: 



Pol lination is the transfer of pollen from the anther to the 

 receptive surface of the stigma. 



Fruiting is the development of ovarian tissue around the seeds 

 after fertilization. 



Sel f pol 1 i nation is the transfer of pollen within the same 

 blossom, tree or variety. 



Cross pollination is the transfer of pollen from one variety 

 to another variety. 



Sel f-f rui tf ul varieties do not require cross pollination. 



Cross unfruitful varieties are incompatible and do not set 

 fruit when cross pollinated. 



Cross fruitful varieties are compatible and do set fruit when 

 cross pollinated. 



No attempt will be made here to review the floral biology asso- 

 ciated with the pollination of fruit or to discuss how compatibility 

 or cultural, environmental, or genetic factors affect pollination. 

 These subjects are, of course, well known to most of you. Also, 

 you all know that most apple varieties are self-unfruitful so a 

 suitable supply of the right kinds of pollen must be provided for 

 optimum pollination and fruitset. Over the years, a number of ways 

 of meeting this need have evolved, the best being the i nterpl anti ng 

 of suitable varieties. 



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This article appeared in The Maryland Fruit Grower . Vol 41 (No. 1) 



