MUST WE REVISE OUR PRUNING PRACTICES? 
E. L. D. SEYMOUR 
Curious and Interesting Experiments in This Country as Well as Abroad Are Forcing the Belief That 
We Are Perhaps Altogether Wrong in Our Assumptions With Regard to the Use of Knife and Shears 
M OW about this business of pruning? Have we been 
overdoing it all these years, at needless cost to our- 
selves and with unnecessary sacrifice of our trees and 
plants? Have we succumbed to a sort of pruning 
hysteria, comparable to the craze for surgical operations that 
seemed to hit the medical world some years ago. when the first 
and favorite prescription for almost any ailment was the knife? 
Upon my soul, it looks like it! And I believe you will agree 
with me when I tell you about the discoveries that Professor 
W. H. Chandler has made up at Cornell University, in his prun- 
ing experiments with fruit trees. As 
a matter of fact, he isn’t the only 
horticulturist that has been working 
at the problem; faint echoes of new, 
surprising truths have been coming 
to us from overseas for some time. 
But his results are so striking and 
so rich in food for thought and 
conjecture that they are mighty 
worth consideration, right now when 
we are thinking about the fall plant- 
ing programme. 
Boiled down, concentrated and 
(with the permission of the Internal 
Revenue Department) double-dis- 
tilled, the conclusions of the Cornell 
experiments are these: 
Pruning a young tree definitely 
reduces the amount of its growth and, 
for some years at least, its yield. 
The stimulating, invigorating effect 
of pruning — about which we have heard 
so much — is actually only local and 
temporary; the larger, lasting effects are 
depressing and retarding. 
Pruning, like operating, should be 
regarded as a severe measure, to be 
resorted to only when necessary, and to be avoided whenever 
possible. 
These are rather revolutionary conclusions, are they not, 
especially when we think of the ruthless annual trimming that 
most Peach orchards receive? Of course, the argument can 
still be advanced that pruning does stimulate early fruiting, and 
that that is sometimes what we want most of all. But there 
is no more real logic in the statement than in the equally true 
one that by constant coaching and continually repressing the 
play spirit, we can induce almost any child to become more or 
less of a prodigy of learning at a tender age. Who wants an 
infant Diogenes at the cost of a stunted body, a shortened life- 
time, a warped, unbalanced development? — which, in greater 
or less degree, is the cost of precocious wisdom or fruitfulness 
in human young, or young plants, as the case may be. 
What Practical Experiments Tel) About Pruning 
H ERE, as a starter, are some of the things Professor Chandler 
has done and learned during the ten or more years he has 
been investigating the responses of different kinds of fruit trees 
to different kinds of pruning: — He took a block of thirty Apple 
trees, one year old from the graft, and pruned sixteen, leaving 
the other fourteen untouched. In June, the sixteen before 
pruning, averaged 173 leaves apiece; in pruning he reduced 
these to an average of 44. The unpruned trees averaged 143 
leaves each. In October he carefully counted the leaves on all 
the trees, then dug them up and weighed first the top growth 
and then the roots of each tree. The average figures per tree 
after these four months growth were — 
Pruned trees average 149 leaves: their tops weighed 168 grams; roots 24 grams 
Unpruned trees “ 272 “ “ “ “ 236 “ “ 33 “ 
Again, he submitted a block of two year old Delicious Apple 
trees to three degrees of pruning, forty-one being left unpruned, 
thirty-three being pruned lightly and 
thirty-nine being pruned severely, the 
pruning being done in May. In this case 
he carefully measured the leaf surface of 
each tree before and after pruning and at the end of the grow- 
ing season, and then dug up the plants and weighed their tops 
and roots separately. The results, which can best be compared 
in table form, were these — 
TREATMENT 
AVERAGE LEAF SURFACE PER TREE 
AVERAGE WEIGHT END 
OF SEASON 
BEFORE 
PRUNING 
AFTER 
PRUNING 
END OF 
SEASON 
ROOTS 
TOPS 
41 unpruned 
33 lightly pr. 
39 heavily “ 
756 sq. in. 
819 “ “ 
775 
736 sq. in. 
470 “ “ 
291 “ ‘ 
1737 sq. in. 
1219 “ “ 
893 “ “ 
208 grams 
166 “ 
125 “ 
684 grams 
558 ' 
494 “ 
Not much doubt left as to the effect of pruning there, is there? 
Moreover, as he began to take note of the performances of older 
trees as they came into bearing, after having been subjected to 
different pruning systems. Professor Chandler found the same 
results, though they were expressed in different terms. For 
instance, the average yield for the first two or three years in an 
Apple orchard in which each alternate tree in each variety row 
was pruned differently, has been fifty per cent, greater in the case 
of the trees that have received practically no pruning. Further- 
more, in walking through the orchard, the unpruned trees can 
invariably be picked out because of their larger size, except where 
winter injury or some other recognized factor other than the 
THREE YEAR OLD APPLE TREES 
On the left an unpruned specimen, on the 
right a tree pruned on single leader sys- 
tem; otherwise treatment has been identical 
27 
