WINTER PRUNING EXPERIMENTS WITH APPLE TREES. 149 
The apparently greater influence here of the number of blossoms 
than the number of fruits in preventing the formation of blossom buds 
bears out the inference drawn by Roberts from his observation of 
mature apple trees in America (Journal of Pomology, November 1920). 
But it is questionable whether the explanation he offers — that the 
growth is reduced below the amount required for the formation of 
blossom buds — is applicable to our immature trees ; all of them made 
a considerable growth in 1920, including those which showed the 
least blossom in 1921 ; and on these trees spur growths of one or two 
inches without blossom buds were very frequent. 
The long-spur pruned trees of ' Allington Pippin ' show signs of 
developing the alternate-bearing habit. Four of the eight trees had 
less blossom in 1921 than in 1920, but all of them bore an increased 
number of fruits in 1921. One tree, which produced the greatest 
weight of fruit in 1920, had a greatly increased number of blossoms 
in 1921, but this seems to have weakened it, for the increase of its 
crop in 1921 was smaller than that of any other of the eight trees. 
At least two other varieties, * Grenadier ' and ' Worcester Pear- 
main/ showed in 1921 a slight decrease in the number of blossoms of 
one or two long-spur pruned trees, but this may be only accidental, 
and is not great enough to deserve special attention. 
Since winter pruning clearly does tend to check the alternate 
bearing habit, even when the pruned trees crop heavily (' Newton 
Wonder '), it should be possible to devise such a modification of 
pruning methods as will almost entirely eliminate the habit. But it 
would obviously be necessary at first to distinguish between trees in 
their " on " year and those in their " off " year. The object must 
clearly be to reduce the amount of blossom they carry in their " on " 
year ; for, as we saw, it seems likely that profuse blossoming has more 
influence than heavy fruiting in causing the alternate-bearing habit. 
If the trees could be pruned hard and their spurs drastically shortened 
in the winter following their " off " year, and merely thinned out or 
lightly pruned in the alternate winter, their cropping should tend to 
become more uniform. 
5. Effect on Growth and Ultimate Size of Tree. 
In attempting to observe the effect of pruning on the growth and 
size of a tree, we at once meet with difficulty in finding a satisfactory 
measure of the characters to be studied. Measurements of the height 
and spread of the branches, while they give some indication, are far 
from satisfactory, owing to the very great difference in the shape of 
the head frequently caused by pruning. With a spreading variety 
like ' Lane's,' for instance, one of the objects of pruning is to keep the 
branches up off the ground. This is accomplished very well by 
current methods, and it results in a rounded or slightly upright head, 
as against the very flattened and drooping head of the unpruned tree. 
Such measurements as we have so far made give so poor an idea of the 
