stuart at zephyr.manawatu.planet.co.nz
Fri Jun 23 17:41:00 EST 1995
>From: A.S.Chamove at massey.ac.nz (Arnold Chamove)
>Date: 15 Jun 1995 02:03:30 GMT
>The advice given for sail pruning is to trim about half off the
>lower branches of pines in order to reduce wind resistance.
>It seem to me that it is the upper branches that offer the most
>wind resistance and the lower, especially the very lowest, branches
>offer almost no resistance to the wind as they are very close to the
>ground and also contribute a lot to photosynthesis.
>(a) keep the very bottom branches
>(b) and trim the highest branches to half
>(c) especially those in the path of the wind (i.e., North South branches
>when there is East West wind)?
You make some good points about sail pruning. We have had some problems
with windthrow in young pines, particularly late autumn, with strong wind
after the soil is saturated. More so 12-15 mths ago than this autumn.
Fortunately el-nino has eased this season. The most common offenders are
poorly formed 1-2 yr old trees. Some nurseries claim using physiologically
aged cuttings (instead of seedlings) reduces the problem because they're
better formed and have better roots. There is much debate about this
however, and it seems the method and timing of wrenching of nursery
seedlings is quite important. ie to the root growth of the subsequently
transplanted tree. The planting method is obviously very important too.
The 1-2 yr windthrown pines seem to retify themselves quite well, although
sometimes at the cost of a small amount of butt sweep and stressed timber.
If the windthrown trees are inclined to rotate in a circular manner (due
to the wind) a solution can be to top the trees ie cut the main stem in
half. This also reduces butt sweep. The trees reform themselves really
well, although with some loss of height growth, but at least you'll get
something established easier than replanting.
Of course if your climate is less severe than ours it would be possible to
employ other methods such as standing the trees up.
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