June, 1933] Pollination and Fruit Setting in the Apple 17 



V. Pollination Experiments in 

 New Hampshire, 1927-1932 



Pollination of Mcintosh: 



In 1927 work was begun to determine the effectiveness of various com- 

 mercial varieties as pollenizers for Mcintosh. In addition to hand pollina- 

 tions in screened cages, observations were made to compare the open set on 

 Mcintosh trees adjacent or near to various other varieties and on those 

 somewhat isolated from other varieties. 



In 1930, reciprocal pollinations were made with Delicious, Gravenstein, 

 and Cortland. 



In 1927 a moderately vigorous 20-year-old Mcintosh tree was enclosed in 

 a wire-screen cage just before the flower buds began to open. This tree was 

 located in a sod orchard and had been fertilized with five pounds of sodium 

 nitrate or ammonium sulfate annually since coming into bearing. 



In 1929 a different Mcintosh tree of corresponding size and vigor was 

 similarly caged in the same sod orchard. 



In 1930 in another orchard which is grown under cultivation with com- 

 bined intercrops and cover crops, tw^o Mcintosh trees were enclosed just 

 before the first blossom buds opened. The cages consisted of wooden 

 frames covered with cheese cloth. These trees were 11 years old (from the 

 time of planting), had borne two crops, and were of ordinary good vigor. 



In 1931 two other trees were tested in the same cultivated orchard. 

 These were also enclosed in cheese-cloth cages. 



To increase the amount of data and to compare effects in differently 

 located sections, a Mcintosh tree was caged in cheese cloth in a southern 

 New Hampshire orchard where normally trees of a given variety come into 

 bloom from four to seven days earlier than at Durham. Two young Cort- 

 land trees w-ere also caged and crosses made. 



Because of the desire to try out some of the new Mclntosh-like sorts, 

 one of the leading questions of growers in New Hampshire is the efficiency 

 of newer varieties as pollenizers. It was therefore concluded that some value 

 to growers might be derived from using a few of the newly originated 

 varieties as pollenizers for Mcintosh. The work was therefore discontinued 

 of testing as pollenizers varieties which had shown themselves to be consist- 

 ently good pollenizers, or had proven less desirable from a standpoint of 

 commercial value. 



Pollen was obtained from the new varieties by removing the anthers 

 from buds gathered as late as possible before the petals began to unfold 

 and before danger of the stamens becoming contaminated by insect visits 

 to the flowers. Since fresh pollen was gathered daily and none was held 

 for use another day, the danger of loss of vitality in the pollen was reduced 

 to a minimum. 



Pollen was placed on the stigmas of opened flowers when the maximum 

 number on a cluster were apparently in a receptive condition. In this way 

 an average of four blossoms per cluster were pollinated. Unopened buds on 

 a cluster, flowers that were apparently near the end of the receptive stage, 

 and imperfect flowers w^ere removed at this time of pollination. 



