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Wisconsin State Horticultural Society / Annual report of the Wisconsin State Horticultural Society for the year ending July 1, 1921
Vol. LI (1921)

Roberts, R. H.
Off-year apple bearing,   pp. 72-78 PDF (1.8 MB)

Page 76

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pruning end-and I want to emphasize pruning especially. When
starting out to modify the growth in the orchards, measure the
results by the growth made by the trees. Find out whether or
not sufficient terminal growth is made so that the second-year
wood forms blossom buds on it. Find out, if there are any
great number of spurs about the trees that do not form blossom
buds. If so, find out whether they are in the undervegetative
class, or in the overvegetative class. Usually the thing that we
have to deal with under most situations is to make the trees more
So we come to a consideration of fertilizers, and one thing
that we are especially interested in is nitrogen fertilizer. This
is for two reasons. In the first place, under very few situations
are the other elements so limited in the soil that they materially
reduce the growth of the trees. Too little nitrogen certainly does
limit growth. In the second place, the spur growth on trees is
made very early in the season. The spurs that form blossom
buds complete their growth in length about the time the tree
comes to full blossom. That means, in most parts of the state
about the 10th or 15th of May. We find that there is practically
no nitrogen measurable in the soil at that time of the year, a
thing that we want to get clearly in mind in relation to fertilizer
In order to enable the trees to make the kind of growth we
want, make an application of a readily available nitrogen fer-
tilizer early in the season, three or four weeks before the trees
can be expected to blossom in your respective localities.
It seems advisable in many of our locations here in the state
to use a clover sod with a quickly available nitrogen fertilizer.
This will give growth, good initial size to the fruit, and better
colored fruit. There is considerable evidence accumulating,
that the difference in growth secured between sod and cultivated
orchards is not one of moisture conditions; it is the difference in
the nitrogen that is available for the tree in the cultivated soil.
QUESTION: What was that last statement?
PROF. ROBERTS: Apparently the difference between cultiva-
tion and sod in the orchard may be its effects on nitrification in
the soil, and not upon big differences in the moisture content.
There is considerable evidence to show that we can get the

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