LEAFLET No. 30 
ARL15
-SOUT4F_ R NFUSI FORM RUST
SLASH an~d LOBLOLLY
APINE i" Me A LA BAMA
PIEDMONT
JACK T. MAY
Associate Forester
J. F. GOGGANS
Assistant Forester
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AGRICULTURAL EXPERIMENT 
STATION
a/t'4,e ALABAMA POLYTECHNIC 
INSTITUTE
APRIL 1951
I=. V. Smitk, Director
Auburn, Alabama
economic importance 20 years ago.
However, the disease has increased to
the point that it is today an important
factor to be considered in growing lob-
lolly and slashpine. To a large extent,
this increase has been caused by wide
spread planting of the more susceptible
trees. Loblolly and slash pines have
been planted on lands originally occu-
pied by longleaf pine, and oaks have
invaded the cut-over or partially stocked
lands.
The disease is similar to many other
rusts in that it must have an alternate
host. It can not spread directly from
pine to pine. The alternate hosts are
oak trees. Water, willow, and laurel
oaks are the most important carriers of
the disease, but blackjack, bluejack,
southern red, turkey and live oaks also
may be hosts.
The infection cycle, from pine to oak
and back to pine, usually takes place
in the spring. The first signs of the
disease appear on pine trees early in
March. The fruiting cankers on pine
produce masses of orange-colored spores
resembling powder. This orange colored
powdery material is carried in the air
by wind or air currents. The spores,
which come in contact with oak leaves,
produce brownish, hair-like bristles on
the under side of the leaves. These hair-
like bristles bear very small dark spores
which can grow on the pine trees. These
small dark spores are carried in the air
until they die or come in contact with
watery parts of the pine tree. Infection
takes place on the growing pine needles
or on the tender, new stem or branch
tips. As a rule, infection does not
occur through the bark.
Southern fusiform rust on pines may
be recognized by long spindle-shaped
swellings on the stem or branches.
These swellings, or cankers, often rup-
ture and cause breaks in the bark and
wood. In early spring, masses of orange
spores may appear in the cracks created
by the swelling. Sometimes little, if
any, swelling takes place, but pitch
pushes out from the cankerous area.
SOUTHERN FUSIFORM RUST
DAMAGE
The southern fusiform rust fungus
causes only minor injury to its alter-
nate hosts, the oaks. A small amount
of leaf spotting is the only sign of the
disease.
The disease affects loblolly and slash
pines of all ages, from seedlings to
mature trees. The amount of damage
on any infected tree may vary from
light to heavy. A trunk or stem canker
always lowers the quality or reduces
the usefulness of the affected tree. More
important, a trunk canker may kill the
tree. It may weaken the stem to such
an extent that it is easily broken by
wind (Figure 1). Loss from stem in-
fection is highest in trees of seedling
to pole stage.
Branch infections that never reach
the stem have little effect on growth
or use of the tree. Branch infections
occuring within about 15 inches of the
trunk, as in Figure 2, often spread and
develop into stem cankers, as shown in
Figure 3. Branch infections also serve
as a large source of spores for spread of
the disease.
Results of the Piedmont Region study
showed that about one-fourth of all
the trees in unmixed plantations of
loblolly and slash pine were infected
with stem or branch cankers. In the
plantations examined, 14 per cent of the
loblolly pine stems and 17 per cent of
the slash pine stems were infected. The
slight difference between the amount
of infection on the two species is not im-
portant. Individual stands were found
with more than on-half of the trees in
a diseased condition. In one 13-year-old
loblolly pine plantation, 116 trees per
acre were found on the ground due to
this disease.
Damage that would not be important
in heavily stocked natural stands may
often prove serious in plantations that
start with fewer trees per acre. The
average survival of slash pine in the
pure plantations observed in the Pied-
mont study was one-half of the original
[2]
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FIGURE 1. Stem of a slosh pine broken at the point of southern fusiform rust infection.
Stem infection losses arc highest in trees from seedling to pole stage.
FIGURE 2. Limb infection shown here was less than 15 inches from the stem of the
tree. Such infection will finally reach the stem if limb is not pruned.
FIGURE 3. This is what happens if infected limbs are not pruned. In this case the
limb infection has moved into the stem of the tree.
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trees planted. The average survival of
loblolly pine in the pure plantations
observed was 8 out of every 10 trees
planted. The reduction in the number
of trees caused by the greater loss of
slash pine can be overcome by planting
at a closer spacing than that required for
loblolly. Plantations with poor stands
emphasize the need for proper and
light cutting practices.
Total losses in natural stands and in
plantations will vary with:
1. Species of pine
2. Number of trees per acre
3. Amount of infection
4. Cutting practices.
TIMBER STAND IMPROVEMENT
aC UTILIZATION
The heights at which cankers were
observed on the trees indicated that
much of the infection took place within
the first 5 years after planting. Swell-
ing of the stem or branch can usually
be noticed during the first or second
year after infection occurs. In the Pied-
mont study, it was found that the older
saplings were not infected as often as
the younger seedlings. When making
early cuttings, it is advisable to select
the better trees that are to be left for
the final harvest. These trees should
not have stem infection. An attempt
should be made to use the worst in-
fected trees in the first cutting. Other-
wise they may die before the next
cutting.
Pruning of the infected branches be-
fore the swelling reaches the trunk will
reduce losses in plantations and in nat-
ural stands. Prunings can save many
trees that later can be cut -at a profit.
All branches bearing cankers less than
15 to 18 inches from the stem (Figure
2) should be pruned from seedlings
and saplings that are otherwise clear
of stem infection. Swellings that have
reached the trunk must be treated as
stem infections, because the trees will
eventually be killed or their value will
be lowered. Pruning is most effective
before the trees are 10 feet high. How-
ever, pruning should not be'neglected
on older trees that have branch in-
fection closer than 15 to 18 inches from
the stem.
Trees with stem canker should not
be cut just because they are diseased.
They may be permitted to grow as long
as there is a normal increase in size or
until they can be cut at a profit. With
a constantly increasing market for
fence posts and pulpwood, commercial
thinnings are possible in young stands
with trees of 5 inches or larger in
diameter at breast height. A 5-inch
diameter tree will often furnish three
or four posts of 6-foot length, if' used
to a minimum of 2 inches inside bark
at the small end. Small fence posts
when treated, will last as long as larger
posts.
The crown length in relation to total
height of the tree is a good indicator
of the time when thinnings are needed.
When the crown length becomes short-
ened to about one-third of the total
height, some of the trees must be cut.
Otherwise there is a reduction in diam-
eter growth as a result of competition
of the crowns for direct sunlight and
growing space. Early thinnings or sal-
vage cuttings are made to remove the
most severely damaged and stem-cank-
ered trees. Such cuttings should reduce
the number of trees in the stand by
one-fourth to one-third of the total.
Badly damaged trees, such as those that
have had the bark killed by canker and
the wood partially 
destroyed 
(Figure
4), may show signs of bending or
breaking off. They should be cut before
they break and fall over. Small trees,
such as the one shown in Figure 6, do
not contain any commonly usable ma-
terial. They can be left until the next
thinning, by which time they will prob-
ably be large enough for post material.
Trees that have not been too badly
damaged (Figure 5) may often be left
4until a second thinning and then re-
moved as either pulpwood or post
material.
[4]
FIGURE 4. Severity of stem infection is
shown by depth to which pencil is inserted
at point of infection. This tree is likely
to be blown over by wind.
FIGURE 5. This type of infection is not
serious enough to justify immediate cut-
ting. At a later thinning, it can be re-
moved either for pulpwood or fence posts.
FIGURE 6. Small trees with large infec-
tions, as shown here, should be cut and
used as soon as they are large enough for
fence post material.
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In a sample thinning of a 13-year-
old loblolly pine stand near Auburn, the
more heavily infected trees and trees
of poor form were removed. With an
original spacing of 6 by 6 feet, the
survival was nine out of ten trees. Of
the trees that had died, about one-half
had been killed by the southern fusi-
form rust between the 10th and 13th
year. One-fourth of the remaining trees
had serious infection. The thinning re-
moved about 40 per cent of the stand
and yielded 1,100 fence posts per
acre, or equal to about 81/2 cords
of pulpwood. Another thinning after
about 5 years might remove the
remaining trees 
with stem infec-
tions and poor shape or form. The next
thinning will leave the stand in good
condition for the development of a
final crop of timber. These remaining
trees can yield such valuable products
as sawlogs, poles, and piling.
RECOMMENDATIONS
TREATMENT 4. YOUNG
PINE STANDS
Loblolly and slash pine can be grown
by farmers and other land owners in
the Piedmont Region of Alabama with-
out undue losses from the southern
fusiform rust if proper treatments and
cutting methods are used. Recommen-
dations for such practices include:
1. Pruning of infected branches.
2. Early thinnings that use the worst
infected stems as soon as they are large
enough for fuelwood, fence posts, or
pulpwood. Any stem-infected tree that
is not in immediate danger of being
killed or blown down should be left to
grow unless its removal would benefit
near-by trees.
3. Periodic thinnings that salvage
additional badly infected trees before
they are killed or blown down.
[ 61