Pine Decline in South Carolina
I am not a scientist or a researcher. Here are my experiences with pine decline and pine
mortality.
In 2001, I was called to a landowner’s property
because there were patches of longleaf pines
dying. The longleaf stand had been burned in
March of 2000 with a very hot prescribed fire
with char marks as high as 12 feet on some
trees. On June 3, 2001, the stand was
released with Pronone forest herbicide. Three
weeks later, I was called to come identity what
was killing the longleaf pines.
The mortality areas were in circles and
included very mature to grass stage seedlings.
The circles varied in size but some of them
were touching and beginning to form figure
eights with the mortality pattern. One of the
circles had loblolly pines and they, too, had
died.
Dr. Larry Nelson, Vegetative Specialist with
Clemson Extension came to the site. He did
not know why the trees were dying but ruled
Figure 1 Longleaf 1.5 yrs. after a hot prescribed fire in Colleton
County. Photo taken in August. The needles stopped growing
the previous March/April. Notice the longleaf in the
background.
out Annosum root rot. Experts from the US
Forest Service and others were called in. All
that could be obtained was that it was not
Annosum root rot.
I contacted Dr. Frank Tainter, retired Forest Pathology Professor from Clemson University. He
asked that I dig a root of an infected tree and mail it to his home (the root took 3 days to reach
his home). His reply was, whatever was there had died (the fungi) and whatever it was, he had
never seen before.
A month or two later, I was called to another site where longleaf was dying. Again, there were
the high scorch marks of a previous burn and the trees were exhibiting the same symptoms as
the first site. This elated me as whatever was causing the trees to die was not an anomaly.
Through contacts throughout the southeast, I received a phone call from Mark Hainds of the
Longleaf Alliance. He had heard that what may be causing the trees to die might be
Leptographium spp. and Dr. Lori Eckhardt had done her dissertation and was continuing to
research the fungi and associated insects. By the time I located Dr. Eckhardt, she had just
been hired by Auburn University.
Since that time, I too have been learning about Leptographium spp and its associated insects.
What causes the tree to get pine decline
At first, it was easy to see the site disturbance that caused stress to the pines so that the
Hylastes and other beetles could attack and feed on the root systems. A hot prescribed fire
leaving high scorch marks, mechanical disturbances such as removing all understory so that the
pine straw can be raked, et cetera. Then it became more difficult to determine the stressor or
stressors: drought, not thinning on time, logging in the wet period, too much rain, et cetera.
When the trees become stressed, then they are candidates for pine decline.
Soil types and pine species
Pine decline can be found on most soil types but is observed predominantly on sandy loam, or
sandy clay loam and moderately well-drained to well drain soil types.
Leptographium and the associated root feeding beetles can be found in longleaf, loblolly and
shortleaf pines. Thus far, it is far less prevalent in slash pine. However, if the slash pine are
offsite, then it will be susceptible to stress.
Longleaf is the predominant species
that inhabited the lower and upper
coastal plains and the lower piedmont
area. Loblolly is considered an offsite
species where longleaf was native.
The research is showing that a lot of
the loblolly planted in the longleaf
areas are under stress and prone to
pine decline.
What to look for if you suspect
pine decline.
Luckily, there are a hosts of
symptoms that can lead one to
suspect pine decline: no last year
needles on the lower limbs, curving of
the lower smaller branches as if they
Figure 2 Late spring in Lexington County. The needles have a slight off
are drying even if they have needles
color which I call a gray green. By April, the buds should have needles on
them.
on them, the top of the tree (top 1020% crown) has both last year and
current year needles. You may see dead trees with or without bark that are broken anywhere
from 3 to 25 feet up. Longleaf can exhibit an almost wilting appearance in their needles and
sometimes have a grayish green tent. If you see
new growth on longleaf that is 3 to 4 inches long
and it is August, there is an excellent chance that
the tree has pine decline. Sometimes it is isolated
trees or appears that way. Sometimes, it is
apparent that the trees are dying in large circles.
If the stand is left alone, the mortality of these
circles spread out and the circles begin to touch
forming figure 8’s.
Next step
Figure 3 Loblolly in the summer with no last year needles
One day, I was digging roots for someone when a forester commented that the roots were the
last frontier of a pine tree. I had never thought of it like that but it may be one reason that pine
decline has been misdiagnosed or ignored as the evidence of a beetle attack is below ground.
Digging roots
To dig the roots, take a sharp shovel and dig down around the tree trunk until a large root can
be located. Sometimes it may be hard to find on deeper sands. Excavate the root carefully not
disturbing the outer bark. When excavating the root, I use both a shovel and a Pulaski
depending upon which is needed at the time.
Look carefully as you are digging as
there may be evidence that can easily
be overlooked such as a dead dried
out smaller root or clumps of dirt that
have formed around the resin that the
root is secreting.
After a root has been located, if there
are no signs on the upper side of the
root turn it over and look. Sometimes
there is a lot more evidence on the
underneath side. A main root can be 3 inches to a foot below ground. Excavate about 3-4 feet
of the root. Using a Pulaski or ax, cut the root near the trunk of the tree. Generally, if the root
has been attacked
by Hylastes spp.
and other vector
insects, the root can
be brought up and
broken off near the
point where it has
been uncovered.
However,
sometimes, large
underneath roots
may prevent further
Figure 4 The black is the blue stain and the whitish is where the fungi is
breaking open the root.
excavation so a
sharp hatchet is
needed to cut other
roots. Once the root has been removed, it may need to have the dirt removed using water.
Clear evidence are marks perpendicular to the root where the Hylastes spp have chewed on the
root. The bark beetles feed on the cambium just as the engraver beetles or SPB. Like SPB and
other beetles, they release a blue stain fungi while feeding.
Figure 5 A main root from the trunk with evidence of Hylastes feeding.
“Infected primary roots will have blue –stain and resin soaked lesions caused by Leptographium
or Ophiostomatoid fungi (L. truncatum, L. procerum, L. terebrantis, G. huntii, G. alacris). This
group of fungi is present in the roots because of their association with the various root feeding
bark beetles (Hylastes salesbrosus, H. tenuis, H. opacus, Pachylobius picivorus, Hylobius
pales, and Dendroctonus terebrans). Just like their above-ground counter parts, these rootfeeding insects will vector the Leptographium and Grosmannia fungi or create wounds in the
roots that will allow the fungi to enter. Beyond the lesions, the fine roots are either damaged or
significantly reduced in number.” (Pine Decline PD090208) (This paragraph was copied but the
new current names for two of the fungi replaced the old nomenclature.)
Lesions may have blue-stain but looks black and there may be resin stuck to the root with dirt
around it so that it lesions are not readily identifiable. A pocket knife can be used to cut it away
the resin pitch from the root.
A little more about the fungi and insects
Leptographium procerum and L. Terebrantis are native with L. Terebrantis being a bit more
virulent. Grosmannia huntii and G. alacris are not native to the US and are more virulent. Of
the vectors, Hylastes opacus is non-native as well.
Several years ago, Dr. Eckhardt and her research team took samples of the fungi and insects to
South Africa to do DNA testing with Dr. Michael J. Wingfield (world authority on Leptographium
and Grosmannia). Samples from SC were included from roots and insects mailed to the lab. It
was found that the non-native fungi and insect were native to Europe and had also been
introduced to South Africa.
What is the next step?
If a forest landowner wishes to know exactly what is in the roots, I send them to Auburn
University. I belong to the Forest Health Cooperative, Auburn University. The roots are dug,
placed on ice and shipped overnight to AU to prevent drying out. It takes 3 to 4 weeks for the
lab to culture the medium to determine which fungus or fungi is present in the roots. The roots
are also tested for other fungi which are: P. cinnimomi, (Little leaf) and H. irregulare (formerly H.
annosus).
The results gives a landowner an idea of what to do next. For example, one landowner has a
silvopasture with about 30 pine sawtimber trees per acre. His pines have L. procerum and he
loses about 1 tree per acre per year. On other stands that have the more virulent fungi, the
mortality is higher.
Silvicultural Practices to prevent PD
Thin when the trees need to be thinned regardless of the dollar amount. Not thinning when the
trees need it places them under stress.
Plant the correct species on the correct soil type to prevent stress.
Keep track (like track hoes) equipment or soil disturbance equipment out of the timber stand.
Do not thin when the tract is wet especially the loam and clay sites.
Make sure that the thinning crew does not skin any trees except the turn trees and they are
removed.
Use lower intensity prescribed fires. Back in the old days, especially with longleaf, we used to
say the higher the scorch marks the better. Today, using that same burning technique will
guarantee pine decline in the timber stand.
If planting in an area with hard pans, pay someone to break the hard pans with a shank plow or
other device before planting.
Shorten the rotation age of your timber stand.
All timber owners are going to have to stay on top of their stand and manage it. No longer do
we have the option of saying, “I don’t need the money right now; The price of pulpwood is too
low; I don’t have the time right now. When your timber stand needs thinning, Thin IT!
If you already have Pine Decline
The first thing you should know is, Do NOT Thin your pines. This is a silvicultural practice for
protecting your stand against above ground beetles (SPB, et cetera) but it causes the
underground feeders to spread.
Once a tree is severed that has beetles in it, it begins to dry. Drying may take up to 3 years
depending upon the soil type. The beetles will leave the drying roots to feed on other trees.
About 1.5 to 2 years after a thinning, the landowner will observe dying trees.
Once a stand has pine decline, there is no research that gives an alternative on how to get rid of
the insects or stop the fungi. When mortality exceeds pine growth, it is time to clearcut no
matter how small the pines are.
Reforestation
The beetles associated with pine decline do not like feeding on seedling roots but they will move
to seedling roots when the mature tree roots dry out. Initial feeding vectors the fungi, thus
infecting the new seedlings with either Leptogrpahium or Grosmannia or both. Ergo, using our
normal time table of clearcut, wait one growing season, site prepare and plant may not work.
Because the beetles stay in the root system until it starts drying out, they may still be present
when the site is replanted in seedlings. Their roots start drying out and they are looking for
food.
There is a longleaf site in Lexington County that had about 900 to 3000 longleaf seedlings in
place before the clearcut. This site had Grosmannia huntii and G. alacris. It was the 3rd site
that I had seen and it was cultured by AU in 2003. This was my training site for years until the
clearcut.
The following growing season, I returned. The seedlings are either dead or stunted with
needles only 3 to 4 inches long. The roots were dug and the feeding marks of the Hylastes
beetles could easily be seen. There could not be a healthy seedling located on the 50 acres.
Where is pine decline?
The Forest Health Cooperative has documented pine decline in: Aiken, Bamberg, Calhoun,
Clarendon, Colleton, Darlington, Lexington, Orangeburg Richland and Sumter counties for both
longleaf and loblolly pines through roots that I have mailed. It is becoming very prevalent and I
am finding pine decline more often. The ages of stands have been from 17 years old to 60
years old. All have had stressors varying from hot prescribed fires to not being thinned on time,
et cetera.
Questions???
There are people who say that Leptographium does not kill trees. It weakens them and other
things such as SPB kills the infected pines. Research shows that the fungi does not grow when
injected into healthy pines. Also, if the roots have to be shipped over night to keep them from
drying out, how does the fungi stay alive when the Hylastes and other root feeding beetles fly
above ground?
This is Dr. Eckhardt’s reply to these questions.
Lepto has been inoculated into healthy trees and we have published several papers where we
have done so for pathogenicity tests. But when a tree is heathy it can, let's say, hold the fungus
at bay, so the resin components act fungistatically. The fungi is still alive but can't really spread.
As the tree becomes stressed, the fungus can begin to grow and stress the tree more attracting
more insects to come and feed on the root system. The insects will test feed on healthy trees
infecting them and then come back and feed more at a later time as the trees become more
stressed. We have not had the SPB populations as we have had in the past, so more above
ground symptoms are being presented because these weakened trees are not being taken out
in a SPB outbreak.
As far as the heat killing the fungus in transport, that is not exactly what happens. The roots
need to hold their moisture. When you don't pack with ice or send overnight, the roots dry out
and then the fungus is hard to isolate. The beetles body keeps the spores at a constant
temperature and keeps them viable so when the beetle feeds and tunnels and the spores wash
off in the resin, they can then germinate and grow. (E-mail, 11-20-2014)
Conclusion.
If you have questions about Lepto or any part, please ask me. Even after more than 15 years of
research there are still many unknowns about pine decline. If you want me to help you learn
what to look for below and above ground, e-mail me or call me at (803) 534-6280;
[email protected]. I will be glad to help.
On May 6th 2015, there will be a meeting in SC on pine decline. Most likely, the meeting
will be held at the Edisto Research and Education Center outside of Blackville, SC on US
78.