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.