June, 19v^3J Pollination and Fruit Setting in the Apple 21 



fruit on two to three per cent of the blossoming spurs after self-polhnation 

 is usuahy the case with Mcintosh. 



That varieties differ among themselves in the ability to poUenize Mcin- 

 tosh is also indicated. Baldwm seems to be the least satisfactory, but this 

 is to be expected for the results of numerous investigators show that Bald- 

 win is an unsatisfactory poUenizer tor many other varieties. Where Bald- 

 win pollen was used on Mcintosh the highest and lowest set is seen to be 

 18.6 and 4.5 per cent, respectively, of the spurs that blossomed. This is 

 far below the standard for a commercial crop of Mcintosh. 



Gravenstein and Red Gravenstein are also quite unsatisfactory as pollen- 

 izers for Mcintosh. In only one year out of five was the set of spurs above 

 30 per cent where these pollen varieties were used. Two to 10 per cent was 

 the usual set of blossom spurs. Although slightly better on the average 

 than Baldwin, Gravenstein is far from being dependable in producing a 

 commercial crop of Mcintosh. 



Delicious seems to be the variety most constant in ability to cause a set 

 of fruit on Mcintosh. During the five years' experiments the percentage of 

 blossom spurs setting fruit on Mcintosh has been more constant when 

 Delicious pollen was used than with any of the other good pollenizers. This 

 is true whether the trees were grown m sod or under cultivation. 



The percentage of blossom spurs setting fruit on Mcintosh varied from 

 63 to 7S per cent when this pollenizer was used. This is a remarkably small 

 variation. A few other varieties may have caused a larger set when used as 

 pollenizers but this is not necessarily an advantage. It might necessitate 

 heavy subsequent thinning and even then be somewhat detrimental to the 

 normal annual-bearing habits of the Mcintosh. 



Melba likewise seems to be a reliable pollenizer. The low results obtained 

 on the Tuttle farm in 1931 were due to a somewhat weak growing condi- 

 tion in the tree used in the experiment, as indicated by the results of all 

 other pollenizers used with that tree. 



Cortland, Milton and Wagener may also be considered very satisfactory 

 pollenizers. 



Although tested fewer years Fameuse, Lobo, Medina, Oldenburg, Red 

 Astrachan, and Wealthy also seem promising as pollenizers for Mcintosh. 

 The actual set of fruit on Mcintosh when these varieties are used as pollen- 

 izers has not dift'ered greatly from the results obtained with Delicious 

 pollen. 



One problem connected with the development of good commercial apples 

 is the shape or form of the fruit. This becomes important when one consid- 

 ers the difficulties in packing lopsided fruit and its lower market valvie. 

 That lopsidedness of Mcintosh fruits in New Hampshire is due largely to 

 lack of satisfactory pollination is seen from a comparison of Tables I, II, 

 and III. The varieties that are notably poor pollenizers for Mcintosh, 

 namely Mcintosh, Baldwin and Gravenstein, cause a greater development 

 of lopsided Mcintosh fruits than when the more satisfactory pollenizers 

 are used. 



It is apparent that this is connected with poor pollenizing ability \vhen 

 one views Table III. One also sees that with these pollenizers Mcintosh 

 develops an unusually small number of seeds. These have been found to 

 exhibit poorer germinating power than seeds from Mcintosh poUenized by 

 the better pollenizers. 



