Mistletoe, Lichens, Ball Moss and
Ball moss, Spanish moss, lichens and mistletoe
are commonly found growing on shade trees in Texas. Of these,
only mistletoe is classed as a parasitic plant on ornamental
shade trees. Lichens, ball moss, and Spanish moss, although
found on trees, are not feeding on the tree, but only using
the tree for support.
Mistletoe is a tree parasitic plant that derives
its food directly from trees. The haustoria or "feeding
structures" of the mistletoe grows into the vascular
system of the tree and derives their nutrients from the sap
flow of the tree. Mistletoe is spread by birds feeding on
the berries and spreading the seed in their droppings onto
other limbs. The seed germinates into the rough bark of the
tree and the haustoria then grows into the vascular system.
Mechanically removing the mistletoe from the
tree is the only control method currently recommended. Mistletoe
is removed with a hoe or knife from a limb. If the removal
is to last for a period of time, it is necessary to take a
knife or some other type of sharp instrument and remove that
part of the wood where the haustoria is located. To merely
cut the mistletoe from the tree at the bark layer will eliminate
it for a short time but recovery will begin immediately.
Lichens are bluish-green to gray paper-thin
plants that grow on the outside bark of the tree. Their growth
becomes very dense and upright on some plants, while on others
they are flat on the bark of the tree. Lichens can be found
on rocks and other inanimate objects indicating that they
are receiving no nutrients from the host tree, as is the case
with mistletoe. Lichens are a combination of algae and fungi
growing together in what is known as a symbiotic relationship.
The trees are involved only in that they are the object on
which the lichen is growing.
Although found in most areas of Texas, lichens
are more of a problem along the Gulf Coast and in the more
humid areas. Lichens are most often thought of as an indicator
of poor tree vigor. Lichens have a requirement for a certain
amount of sunlight so if the tree is healthy and has dense
foliage, the lichens do not have a chance to grow and develop.
When the trees are weak due to other causes, lichens can proliferate
and cause a great deal of concern. Thus it is very important
that trees be maintained to insure maximum foliage. Currently
there is no chemical control for lichens. In the past, such
compounds as copper bordeaux have been used for control. Re-growth
occurred soon after the chemicals were washed off. Even though
the copper bordeaux will eliminate the organisms for a short
period of time, it is not recommended due to its short term
effect, and because its use is not currently cleared by the
Environmental Protection Agency (EPA).
Ball moss is the grayish-green "pincushion-like"
or tufted growth seen on the bark of a number of Texas shade
trees. Ball moss is an epiphytic plant, meaning it derives
its nutrition from the air, not from the tree. It causes a
great deal of worry for homeowners who fear that the ball
moss is killing their trees. Trees heavily infested with ball
moss have been observed to undergo a slow decline, because
the moss can smother lower limbs of a tree simply through
shading of buds. In general though, moderate populations of
ball moss are not harmful to a healthy, actively growing tree.
If your trees have a heavy infestation of ball
moss or you simply don't like the look of the moss in your
trees, there are effective control measures that can be taken.
When there is only a light infestation of ball
moss present, just take good care of your trees and don't
worry - no chemical sprays are needed. However, if large numbers
are present, here's your ball moss battle plan:
1. Prune out and destroy dead or severely weakened
branches, especially those encrusted with the moss.
2. Treat with Kocide 101 in spring (February
3. Use Kocide 101 at 6 lb./100 gallons of water
or 6 tablespoons per gallon of water.
4. Invigorate trees with an application of a slow-release
fertilizer such as 19-5-9. Apply 2 pounds (2 cups) per inch
diameter of the tree trunk. Irrigate deeply and regularly
throughout both the growing and dormant seasons.
5. Re-treat any tree with signs of active ball moss after
When controlling ball moss using Kocide 101,
it is important that all of the moss be covered and saturated
with the spray solution. To be effective, applications must
be made before or during the rainy season, usually mid-February
to early May. This insures that the Kocide is on the ball
moss and waiting to be absorbed into the moss with the next
spring rain. Spray equipment such as a 50-gallon skid mount
sprayer which applies chemical 30 to 40 feet high is available
from some equipment rental stores. Of course, you must have
a pickup truck available to haul the sprayer.
Two cautions about using Kocide 101: 1) the
chemical has a bluish color and can stain brick walls, roofs
and driveways, and 2) Kocide will damage foliage of peaches,
plums, nectarines and apricots.
Ball moss treated with Kocide will die over
a 6 to 12 month period but will remain in the tree because
of its "hold fasts," which attaches it to the tree.
In most cases, it will take 18 months for these "hold
fasts" to decay sufficiently so that the ball moss will
be dropped from the tree. Once Kocide has been applied and
the moss is killed, it will become dark gray in color and
the "leaf like" structures will point downward rather
than be in an upright position.
Even though baking soda has been shown effective
for ball moss control at the rate of 40 pounds of baking soda
per 100 gallons of water, Mr. Arm & Hammer has not put
it on the label SO WE CAN'T RECOMMEND IT! However, if it is
used, it should be applied exactly as Kocide 101 is.
Another recommended method to control ball
moss is "de-mossing." This procedure consists of
pruning out dead or weak branches, plus physically scraping
or picking all of the moss throughout the tree. This procedure
will give good control for about 2 to 3 years. Since some
of the tiny moss tufts are unavoidably missed, a new crop
of ball moss will eventually appear again.
Unlike ball moss, Spanish moss does not develop
the very dense growth around the limbs and for that reason
is not considered to be a problem on trees. In Texas, Spanish
moss is associated with an atomosphere of the "old South".
The "old South" is the area in which it is found
normally and there it is prized by the homeowners. No control