Tree Improvement Program Project Report 2006 / 2007

.2.9 Crown Prun ng Techn que for
North Okanagan Lodgepole
P ne Seed Orchards.
SPU 0720
Chr s Walsh and Joe Webber
As orchards mature, crown form eventually becomes either
too high or too bushy to manage effectively. In general,
trees taller than 5 to 6 m require some form of topping
and also pruning of lateral branches that extend into the
rows to allow access for tractors and pickers. Experience
from applying other pruning treatments to lodgepole pine
suggests that cone production (both seed and pollen cones)
will drop immediately after pruning but can return to pretreatment
levels within three to five years.
Most north Okanagan lodgepole pine seed orchards
are now at the age where they require crown management
activities. Lodgepole pine seed orchard 230 at Kalamalka
was chosen for a pruning trial starting in 2004 because the
trees were then at an age (12 to 15 years) and height (4 to
6 m) at which crown management must be considered.
This project is testing three levels of height control: control
(no topping), moderate (3.5 to 4.0 m) and severe (2.5 to
3.0 m), in addition to two levels of lateral pruning: tractor
(remove only laterals extending into the row) and picker
(remove extending and upper-crown laterals to improve
crown access). We measured tree response to crownpruning
treatments initially in 2004 and subsequently in
2005 and 2006.
Seed Cone Number
Seed Cone Number
250
200
150
100
50
0
250
200
150
100
50
0
T R E E I M P R O V E M E N T P R O G R A M
2004 2005 2006
P R O J E C T R E P O R T 2 0 0 6 / 2 0 0 7
Results
A complete analysis of all data is available in the final report
for OTIP SPU 0720, distributed to all Pli orchardists. This
report summarizes the data from 2004 to 2006 for cone
counts (whole tree and branch counts) and seed yields (high
and low crown, with and without insect protection).
Cone counts
Figures 41 and 42 show the mean whole-tree seed-cone
counts for each of the three pruning blocks and for the
levels of treatment in the three pruning blocks and two
lateral-pruning sub-blocks. Cone counts dropped (Figure
41) the first year after pruning (existing first-year cones
removed in 2004) and substantially increased in 2006.
Note that because the 2006 cones were already formed
in the remaining branches after pruning in the late fall of
2004, we do not expect pruning regimes to affect these
counts dramatically until 2007. However, it is interesting
to observe that cone counts for the moderate pruning level
are the same as for the control block, and, as expected, cone
counts in the severe block are substantially lower.
Seed-cone counts also varied by levels of topping and
lateral pruning (Figure 42). There were substantially more
cones in the picker-access sub-blocks of both the control
and moderate top-pruning blocks, but not in the severely
pruned block. We observed this trend in 2004 and again in
2006.
Figure 43 shows the mean seed-cone counts for a major
whorl branch in the upper and lower crown. As expected,
there were two to three times more cones in the upper
Con
Mod
Sev
2004 2005 2006
F gure 1. Mean whole-tree seed-cone
counts for each of the three prun ng blocks.
Con Pick
Con Tract
Mod Pick
Mod Tract
Sev Pick
Sev Tract
F gure 2. Mean
whole-tree seed-cone
counts for treatments
n prun ng blocks.
7