Hello my name is Mike Parker. I'm the
tree fruit extension specialist at North Carolina State University. Today we'd
like to talk about planting pecan trees. In North Carolina we plant grafted pecan
trees to get improved varieties. The reason we don't plant seeds is because
pecans are cross pollinated and if we just planted the seeds from pecan tree
the resulting tree would be inferior to most of our nuts. So again when we do
that we graft trees. It's important to understand where the graft union is when
planning pecan trees, because what we like to have is when the tree grows
we'd like to see the base flare out. However this tree that was planted too
deep goes straight into the ground. It does not have that flaring which gives
the tree all kinds of strength during heavy winds especially we have a leaf or
a fruit crop on the tree. So we would like to talk today about how you
properly plant a pecan tree to make sure it is strong and durable and lasts many
years under high winds in North Carolina. In pecan orchards at maturity there will
be seven to eight trees per acre usually spaced 70 by 70 or 80 by 80. However, for
a grower to establish an orchard and to wait for that period of time to fill
that orchard, in North Carolina many of our growers choose to plant high density
orchards. They plant trees with 35 foot spacing between rows, with 35 foot
between trees resulting approximately 35 to 36 trees per acre. By doing this we
get nut production earlier in the life of the orchard to offset the cost of
establishment. Then over time as the trees grow, shading becomes an issue. At
that point time trees are removed and we thin trees out until ultimately at
maturity there are seven to eight trees per acre. Planting high-quality trees is
essential for any successful pecan orchard. Here's some trees that we were
looking at - these are bare rooted trees realizing that in North Carolina the
varieties we plant are all improved - they're grafted trees. We have a root
stock in which we've grafted a scion of our desired variety on top. The reason we
plant grafted trees is because we want desired varieties and the only way that
we can get that is with a grafted tree. If we planted seeds there would be so much
variation from the nuts being cross pollinated that the trees coming up
would not be uniform. So buying a high-quality tree is going
to be essential. Here we have some examples of bare-root trees that have
been purchased. We have our root stock with a graft union here and then the
tree growing out. However it is essential to understand where that graft union is. We know that if we plant pecan trees too deep with this scion variety planted below the surface, it will not root. When we plant trees we like to have
them well rooted but we want the roots as close to the surface as possible. In
North Carolina one of our major issues with pecan trees is the trees blowing
over during tropical storms or hurricanes. When the trees are planted we
want to make sure that this graft union is above the soil line, usually three to
four inches above the soil line. However identifying that graft union is going to
be very difficult in some cases. Another type of tree that can be purchased would
be a potted tree. The potted trees again that we use in North Carolina are going
to be grafted. Here you can see the graft union on this pecan tree and it grew off
from here. So realizing when it's planted, this graft union will need to be 2 to 3
inches - 2 to 3 or 3 to 4 inches above the soil line after the tree has settled.
However, when using a potted tree you have to be very careful with the root
system. You pull the tree out of the pot and you need to look for roots that may
be circling. We want to remove the soil and then find the major root. The problem
is if we do not take care of the roots that are circling in these pots they
will continue to grow in a circle until those roots constrict the tree and
girdle tree and actually result in it dying. If we will look at a tree that
this was not done - this is a young potted pecan tree, but if we look at the root
system, it is growing in circles. It has been in the ground for a year however if
the roots were not parsed out . . . if we look at it here you can see the roots growing
in a circle. Those roots will continue to grow and are large and continue in that
circle until they constrict and girdle the tree. So it is essential when
planning a potted tree that you make sure that you pull out the roots, get rid
of any circling roots. Here I'll come in and pull this away,
because as you can see there are no roots growing outward. When you plant a
tree like this that is not going to be good unless you properly prepare the root
system before planting. You can see it again continue to grow here in a circle
and it's essential that those be parsed out. Sometimes it's difficult to pull
those out. If you cannot pull them out, probably the best option would be to
come in and cut those roots, knowing that every place we make that cut there this
root system will send out new roots that will be able to explore the soil around
them the newly planted tree. When pecan trees are grafted, they're usually
grafted onto a two or three year old root system. They will come in and place
a pin, if you will, a short section of the desired scion variety.
So we look if the graph union is going to be here - you can see it's more of a Z
shaped graft union. Then when the tree grew out, this bud at the top is the
bud that grew out to grow the scion variety. So, again, this is not the graft Union here. The
graft union is going to be down here so the soil needs to be three to four
inches below that graft union when the tree has settled after planting. When
that happens we know that the root system will send out roots near the
surface and then will form that buttressing. Usually a good rule to
follow is plant the trees at the depth that they came other nursery. Many times
you can see where that soil line is. So that many times is a good indicator.
However, make sure that that graft union is above that point. Another type of
graft that is used to propagate pecan trees - probably not used as much now as
it was historically - is called a four flap graft or maybe sometimes referred to
as a banana graft. The root stock, four flaps of bark are cut down - the scion pin
here would have four shaved sides. It would be placed in to the the middle
of these four flaps. Those four flaps will be brought up making contact with the
cambium tissue and then it would be secured. So if we will look at a tree
here, this is where the tree grew out the bottom of the graft, you knew it would be here.
So the planting depth would need to be three to four inches beneath that. Once we've bored our holes, prepping
that hole for planting is going to be crucial as well. We've used
an 18 inch auger to auger our holes. But if we'd go and look at the size of
the hole, it's sort of glazed. The fine particles in the soil have been
compacted, if you will, with the auger going round and round. And if we were
planting a tree into a hole like that the roots have a hard time penetrating
through that layer of glazed soil. If we would look at the sides of the holes
they are glazed. Looking up close like this you can see where, even in
this lighter, sandier soil, there is still a glazed layer that needs to be broken up.
So one of the easiest ways to do that is coming in to use a shovel - hit the side
of the wall and twist. This is essential before planting the trees. Another way
that this can be accomplished is on the auger, you can come in and weld a piece of
large steel such as a railroad spike that sticks out approximately one to two
inches beyond the edge of the auger wall, and as it goes around it will scar up
the wall. However this is one of the easiest ways once our holes have already
been dug. Now that we have our hole dug and we have our hole prepped, we also have to
make sure that our tree is going to fit within the hole. If you look at the trees,
we have a very good root system on this tree - very vigorous. If we would look at
the hole here and plunge it in like that, we would see these roots coming up. That
is not acceptable. It's also not acceptable to take and
come in and put them in a circle around, as they will continue to go around. So
several options here - one is you can come in and dig the hole a little larger, or
you could come in and remove these roots at the edge of the hole. So we'd come in
and cut the roots so that when it goes into the hole that those roots fit
within the hole. In some cases when large vigorous trees are purchased the
taproot is so long that it's very difficult to dig a hole. In that case
some light judicious pruning on the taproot can take place. We do that
because we will try to re-establish the taproot, and in North Carolina we get
very little taproot growth because it's so deep in the soil.
most of our rooting is going to be in the top 18 inches of the soil. When we
make this cut like this, notice that it is a light judicious pruning, at that
point in time we can put the tree back in the hole,
we've cut the roots so that they fit. Once we have our tree placed in the hole,
realizing that the graft union here is approximately three to four inches above.
At that point in time we will start to fill in the hole. Once we have filled the
hole with the soil, realizing it's loosely packed, we would come in and hold
the tree in the upright position, and then we come in and pack the soil around the root
system. There's our planted tree. If we would come in and look at our graft union
here - bottom of the graft union is here - we have four to five inches above the
soil line, realizing this tree will probably continue to sink a little maybe
up to an inch. Once the trees have been planted it is going to be essential that
you water the tree in or water the root zone and saturate the hole.
One of the ways to do that is come in with the remaining soil and make a
soil dam if you will. Then we can put the moisture within that dam. However do not
leave the auger hole partially filled, leaving a two to three inch lip or hole
there, in which to put moisture. The problem with that is if we get heavy
rains that will result in the moisture collecting within that and not running
off and it could drown the tree. With the dam like this if we have issues with
heavy rain we can come in easily and pull back the water dam allowing the
moisture to escape. After planting our pecan tree there's a couple things that
we will want to take notice of. With this tree you can see the remnant of the
water ring that was around the tree. Notice it is elevated, it is not sunken
below ground so that water can run off. Another practice that our growers
use is to paint the bottom 18 to 24 inches of the tree white. They use a
white latex paint - do not use an oil base, it has to be a
latex paint. This helps to prevent temperature fluctuations within the tree.
It also prevents any herbicide drift that may hit the trunk. To paint these we
get a gallon of latex paint, put on a rubber glove put a car wash mitt in,
stick it within the paint and come in and just paint the bottom of the tree. For more information please look at the
North Carolina Pecan Growers website or look at North Carolina State University's
Cooperative Extension website as well. Thank you and good luck with your
endeavor.
