18 N. H. AGR. EXPERIMENT STATION [Bulletin 212 



RESULTS OF WORK IN HATCH AND STATE PROJECTS. 

 Effect of Disbudding on Apple Trees. 



Owing to the widespread budding of fruit trees in New" Hampshire by the 

 ruffed grouse, an investigation of the effect of the removal of buds from fruit 

 spurs upon the growth of the tree, fruit bud formation, fruit setting, and crop 

 production was begun by G. F. Potter and H. A. Rollins last spring. In an or- 

 chard at Contoocook, tw^o blocks of Wealthy were f oimd nearly similar in age 

 and situation, one of which had been budded by the birds and one of which 

 had not. One hundred and sixteen trees from each orchard were labelled, and 

 the diameter of each trunk was recorded. Since increase in trunk diameter is 

 known to be correlated closely with the total growth of root and top of the 

 tree, later figures may be expected to give some information as to whether or 

 not the reduction in number of buds and consequent reduction in foliage of 

 the tree have an appreciable effect upon its growth. Eleven trees were picked 

 at random in each orchard for more detailed investigation. On these trees 

 counts were made to determine the proportion of spurs which had formed 

 blossom buds and on the disbudded trees the proportion which had been 

 taken by the birds. The results on fruit bud formation are given in Table II. 



It will be noted that the average percentage of buds removed on the trees 

 in the disbudded plot was 51 per cent. This represents the budding in the 

 winter of 1922-23. The proportion of fruit buds formed which would open 

 in the spring of 1923 woald not be influenced by the budding during the 

 winter of 1922-23, but it is expected that it would be influenced by the budding 

 during the previous winter. It is known that the orchard was budded during 

 this, the winter of 1921-22, although no records of the exact extent of the bud- 

 ding are available. Some variation in fruit bud formation occurred between 

 the different trees in the same orchards. This raises the question as to whether 

 or not the eleven trees selected in each plot will be representative of the entire 

 orchard. It is probable that they cannot be considered representative on a 

 single year's data. For instance, in the non-disbudded orchard it will be noted 

 that Trees 224, 268, 299 and 307 all produced a small proportion of bloom, 

 although the majority of the trees in this orchard had at least 60 per cent or 

 70 per cent bloom. This error will be corrected after a second season, because 

 the trees which in 1923 had less bloom than the average for the orchard will, in 

 1924, automatically have relatively more bloom. This is because of the known 

 tendency of the Wealthy to blossom every second year. Observations on the 

 per cent of set are given in Table III. These observations are of interest and 

 of very probable significance even at this time. It is shown that the per- 

 centage of set is 71.8 on the trees which had been disbudded and 55.5 on the 

 trees which had not been disbudded. It is known that the percentage of set 

 decreases when the percentage of bloom on the tree is high; the percentage of 

 bloom on the disbudded trees observed was somewhat higher than that on the 

 non-disbudded trees; and we would, therefore, under normal conditions expect 

 that the set would not be quite so good as on the non-disbudded trees which 

 have a lower average per cent of fruit buds. The set, however, was practically 

 ■ 17 per cent better on the disbudded trees. It will be noted also that the 

 average number of fruits per spur was 2.26 on the disbudded trees and 1.95 

 on the non-disbudded trees. 



