May, 1937] Agbicultueal Research in N. H., 1936 25 



thinning. These results were reported by G. F. Potter in a paper to 

 appear in the Proceedings of the American Society for Horticultural 

 Science for 1936. Tests with Baldwin, begun in 1936, include thinning 

 of the blossoms and early thinning of the fruit. The treatments re- 

 duced the crop of 1936 considerably, but improved its quality. The 

 effect on blossom bud formation will be determined early in the season 

 of 1937. 



A second series of plots containing Mcintosh and Spy apples are being 

 treated with different summer sprays. According to results of other 

 investigators, trees sprayed with lime sulphur solution should have a 

 lower rate of photosynthesis than those sprayed with more mild forms 

 of sulphur. Nevertheless at the close of the third season of spraying 

 with these materials, there has been no significant effect on the percent- 

 age bloom. Records of the size and color of fruit, per cent of crop to 

 drop before harvest, shoot growth and trunk diameter increase, as yet 

 show no significant differences due to the spray treatment. (Adams 

 Fund) 



Pollination of Apples 



Data on the cross pollination requirements of Mcintosh, Cortland, 

 ]\Ielba, Milton, Early Mcintosh, and Macoun have been summarized 

 l)y L. P. Latimer in a paper appearing in the Proceedings of the Ameri- 

 can Society for Horticultural Science for 1936. Of these, the Melba, 

 on which about a 23% set was obtained with self-pollination, is the 

 only variety even partially self-fertile. Fruit from self-pollinated blos- 

 soms was smaller than that resulting from cross-pollination. A satis- 

 factory set on any of these varieties can be obtained by pollinating with 

 any other except that Cortland and Early Mcintosh will set no fruit 

 when crossed with one another. 



Further tests indicate that pollen gathered by bees does not effec- 

 tively pollenize flow^ers which they may visit a day or two later. {Pur- 

 nell Fund) 



Pruning Experiment with Apple Trees 



Two tests are in progress under this project conducted by G. F. Pot- 

 ter. A block of Mcintosh and Spy trees planted in 1919 was divided 

 into three plots, in one of which the trees are pruned to the vase form, 

 in the second to the semi-leader type of head, and the third to a full 

 leader type. The results over a period of 17 years have been remark- 

 ably uniform. Up to this time, no appreciable breakage has occiuTcd 

 in any of the plots. Yields have been almost identical. With Mcintosh 

 the vase form trees have an average yield for the period from 1925 to 

 1936 inclusive, of 195 pounds per tree per year; the semi-leader 202, and 

 the full leader 197. Corresponding figures for the Spy, covering the 

 period from 1930 to 1936 inclusive, are for the vase form 270, semi- 

 leader 297, and the full leader 294. Average annual twig growth and 

 increase in tnmk diameter has not varied significantly in the different 

 plots. Without doubt, in a period of 50 or 60 years, the modified leader 

 type of head will prove the strongest. These results indicate that it 

 may be obtained without any measurable loss in growth or production. 



