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The much-maligned ball moss, Tillandsia recurvata, is actually
a bromeliad, related to pineapples and the brilliantly-flowered exotics
seen in greenhouses. Bromeliads can be terrestrial, saxicolous or
epiphytic. Terrestrial species grow, like most plants, with their
roots in the soil. Saxicolous ones grow on rocks and epiphytes grow
on other plants.
Epiphytes are not parasites; none draw any nutrients directly from their
hosts. The advantage bromeliads gain from their arboreal perch is
height. They are elevated beyond the reach of most browsing animals
and receive more sunlight for photosynthesis than they would if growing
on the ground in a tropical forest.
Why is it, then, that ball moss is thought by many to be a scourge worse
than mistletoe? Primarily because of a misunderstanding regarding
how trees grow and eventually lose their lower branches. Look closely
at the trunk of any large tree and you will notice circular patterns in
the bark with indicate the positions of long-dead branches. Throughout
its life, a tree is forming new branches at its growing points and killing
its lower ones. Branching occurs to disperse, both efficiently and
uniformly, the sunlight-catching leaves throughout the canopy of a tree.
Limbs die naturally when their leaves cease to produce enough nutrients
because shading has impaired their ability to photosynthesize. At
any time, a mature tree can be expected to have several limbs in the interior
of its canopy in various stages of decline, and others dead and decaying.
In the absence of ball moss, such a scene does not beg for fantastic explanations.
Now comes the innocent ball moss seed, propelled by wind away from the
flower spike where it formed. Most seeds land on inhospitable sites,
never to grow. A very few become tangled in the bark crevices of
a limb somewhere within a tree's canopy. In such a site, protected
from too much sunlight, they germinate and grow to maturity if rainfall
and atmospheric humidity are sufficient. The ball moss will thrive
until the dead branch supporting it falls due to decay.
In general, ball moss grows best in the interior of trees where it is shielded
from the sun's drying rays. In sites where relative humidity is ample,
ball mass can spread to the upper reaches of a tree and even onto electrical
wires or fences. This phenomenon can be seen near Pleasanton and
in some of the narrow river valleys in the Hill Country.
There are still those who assert the contrary position, claiming ball moss
is detrimental to trees. Another answer to those skeptics is
to point to large, old trees, whose dying, interior branches are fully
clothed with ball moss and then inquire how such a tree, a paragon of its
species, could ever have achieved its lofty status having spent the last
200 years "encumbered" by that native epiphyte?
If one wished to proceed further with such a line of reasoning, one might
also inquire of the skeptics how it happened that any tree was able to
live to maturity before this area was civilized and its woods "freed" from
the "ravages" of ball moss? Will they answer that the aboriginal
Americans spent their days as compulsive arborists busily plucking every
single clump of ball moss?
If your trees are healthy and actively-growing and you cannot stand the
sight of ball moss, just prune out the inner dead wood where it congregates.
Chemical sprays are used by some to kill ball moss, but because of its
tenacious roots, it will remain, dead and very ugly, on the tree for up
to three years until it decays.
If your trees are declining and have more ball moss than your neighbor's
trees, pay an arborist or horticultural consultant to determine the real
cause of their malaise. Just removing ball moss from sick trees will
not cure the underlying problem.
Some "arborists" will still attempt to persuade you to spend large sums
to remove ball moss. They do so for personal pecuniary advantage
and not for the benefit of your trees. |