Austin trees are subject to infestations by a little plant called Ball Moss or Tillandsia recurvata. It is actually quite beautiful. Though dull looking from a distance, it is laced with pretty colors when viewed more closely and has other interesting characteristics which make it an interesting plant. Ball Moss is not a moss, but I will use the word “moss” occasionally in this article for convenience. There are many misunderstanding about Ball Moss and I hope to help set the record straight.
When we observe Ball Moss we see a ball shaped plant with cylindrical leaves and usually with long, stiff, hair-like projections all around it that have little pods on their ends from which the seeds are dispersed. What we are seeing is not one plant that is round, but many little plants clustered together in a colonial association. They are not like most of the plants in the plant kingdom.
Ball moss differs from more conventional plants in the fact that they have no real root system. They have a “pseudo-root” system that serves only to attach the plants to a surface above the ground. Being on the ground seems to be a death sentence for the little colonies, and since small dead limbs usually do end up on the ground, you will often see Ball Moss on the ground with a little twig attached to it and it will be either dead or dying.
Ball Moss can grow on just about any surface including, wires, rocks, fences, and, of course, trees. In Austin you can easily spot the plants growing on the wires that go across Mopac at Rollingwood Dr., right were Zilker Park meets Mopac. I have observed these plants for over 15 years growing on those wires. The colony is not very dense but its numbers have held roughly the same for at least that many years. The pseudo-roots do not get nutrition or water from anything they attach themselves to, and its presence on those wires is proof of at least the fact that they get no nutrition from hosts.
I have read that Ball Moss fixes nitrogen, which means it converts nitrogen gas to other nitrogen compounds such as nitrate and ammonia. This is a good characteristic that makes the plant a good source of food for other plants. One of the crises of our modern time is a shortage of nitrogen in the soil. Nitrogen fixing is vital for restoring the nitrogen levels in soil. By the way, for those of you who do not know, nitrogen is one of the main ingredients in fertilizers and is essential for growing plants on this planet. When the plants die and decay the nitrogen is released in a form that is food to other plants.
It would be a mistake to think of Ball Moss as purely pestilential. It is part of Nature and does not deserve the negative attitudes that I have encountered. The most common misunderstanding I have encountered about Ball Moss is that is it kills the limbs of the tree where it is growing. Whereas it is true that Ball Moss can kill limbs and even trees, it seldom does and never because the Ball Moss is feeding from the tree. Ball moss belongs to the epiphyte group of plants that include Orchids, Pineapple, bromeliads and others. This class of plant is diverse, complex, and complicated. For the trees in Austin, Texas, Ball Moss is the primary concern, though we do have some occurrence of another epiphyte, Spanish Moss. The only way Ball moss can kill a tree or limb is by growing so densely on the host that it prevents the limb or tree from growing leaf. I have seen Ball Moss so dense on trees that twigs of only half an inch in diameter appeared to be six inches in diameter. The Ball Moss was so dense on the limbs that the tree looked more like a “ball moss tree” than the actual tree that was acting as host. I have seen this situation few times in my life.
During the early 1970’s I removed the Ball Moss from a little over 60 Cedar Elm trees growing in the yards in front of the married student housing on Lake Austin Boulevard. They were covered with Ball Moss! There was virtually no leaf growing on the trees because the Ball Moss won the competition for space. This condition went on too long and 7 of the trees from which I removed all the Ball Moss died within a few years. They had been deprived of photosynthesis too long by the Ball Moss preventing leaf from growing. So, Ball Moss can kill trees. To kill a tree Ball Moss must grow so densely that the host tree cannot grow enough leaf to survive. It is that simple. Now, Ball Moss seldom grows that densely.
Trees defend themselves and natural conditions restrict the development of Ball Moss. Some species of trees are more susceptible to suffering such a profusion of Ball Moss. Cedar Elm, Crape Myrtle, and Texas Persimmon are the only species I have seen overcome by Ball Moss. Cedars (Ash Juniper) can get fairly dense colonies of Ball Moss, but I have not seen a Cedar tree overcome with it. Trees have a chemical defense system to protect themselves. Ball Moss may be controlled somewhat by this system, but this is just my theory. I have seen no corroborating research. Other factors regulate Ball Moss.
Humid areas with still air and low sunlight are preferred by Ball Moss, according to the literature, but I have seen many cases that refute this generalization. In any case,some Austin trees make good habitats for the little epiphytes. I have seen two live oaks in the same yard with vastly different amounts of Ball Moss in them. I suspect that this is caused by the different allelopathic chemical defenses of the trees, bark textures, differing air flow, and differing light penetration through the trees. Open canopies allow better air flow and greater penetration of sunlight, and, sometimes, smaller concentrations of Ball Moss. Bark texture is another factor that must not be overlooked or minimized. The pseudo-roots of Ball Moss require a surface that is porous or rough. Two main factors come into play in this situation. First, the little seeds that float in the air much like the dandelion seeds we all have seen must attached to something above the ground and in the right air and light circumstances. The seeds float on little filaments that cling to surfaces as if they are sticky. Once stuck to the right surface in the right place, the seed must germinate and attach pseudo-roots to that surface. This seldom happens on Austin’s’ sycamore trees because the bark is too smooth. On the other hand, a dead or dying limb in the lower parts of a Live Oak tree canopy is good candidate. Considering the fact that young bark is usually smoother than old, dead, or dying limbs, the seeds attach and germinate successfully on the old, dead, or dying limbs. Then, since these limbs are usually in the shaded areas beneath the canopy germination is easily more successful. That is why we see dead limbs on trees with lots of Ball Moss growing on them causing us the think the Ball Moss killed the limb, when in fact, the limb was dead or dying due to the lack of light or some other cause already and, as you can imagine, the bark on these limbs gets rougher and more porous as it dies and dries thus becoming a good place for Ball Moss the grow and multiply. The longer a limb is dead the drier is gets, up to a point, and the better it catches and germinates Ball Moss seeds. So, when you see a limb in the lower part of a canopy covered by Ball Moss, don’t assume the Ball Moss killed it.
I am rather fond of Ball Moss. I can’t help it. I love all living things, even if I do not approve of their actions. If it were not for the fact that I have seen damage caused to trees by Ball Moss I would not make my company available for Ball Moss removal. My policy is to remove Ball Moss from trees as much as possible without causing a large increase in the fee. As you might imagine, picking Ball Moss from a tree is not easy. We have to access limbs all the way to their ends, and Ball Moss usually does not come loose easily. My objective is to keep the Ball Moss under control.
When a tree has an excessive infestation of Ball Moss, I want to remove almost all of it. I think it is not possible to remove all the Ball Moss from a large tree. I can remove so much that it appears to be completely removed even when it is not completely removed. Even if I did remove every last single little plant, I cannot remove the seeds that are already lodged in the bark and they soon germinate and grow. So, why spend money to get every last plant? To take it one step further, if I did find a way to remove all the plants and its seeds, it will still recur because the seeds are air born. This fact may make a case for the use of chemicals to eliminate Ball Moss, but not in my opinion.
I am not a proponent of the use of chemicals in trees. I do not offer it as part of my service because I do not want to put such things into the environment. Sure, you can kill Ball Moss with chemicals, but you will be adding the toxins to your world. I do not want to be a part of this senario. Chemical applicators say it is harmless. They get the chemicals on themselves, proving they think it is harmless. I do not care to enter the debate. I have my opinion and offer it here. No one will refute the fact that the world developed to the point where man began to use chemicals without the use of chemicals. If you are of the opinion that spraying your trees for Ball Moss is okay to do, you will have no trouble finding people to do it for you. I will even offer referals if you ask.
A strong solution of water and baking soda sprayed on trees will kill most of the Ball Moss. It must be done at the right time of the year and is not easy to do. I suggest you get a profesional to do it for you if you want it done. I have had the opportunity to remove Ball Moss from trees on the one year aniversary of the application of baking soda solution. It was a terribly difficult job. The baking soda did not make the moss fall from the branches, though a small percentage did. It just dried up on the trees as though it had been cured or preserved. It was like leather it was so tough. I had to use a saw to detach the pseudo-roots and the old dry carcasses were filled with new Ball Moss plants. A dead Ball Moss colony is a great catcher of Ball Moss seeds and serves doubly well for germination purposes. The client who hired me was not happy about the recourance of the Ball Moss or her need to spend even more money to solve the problem. Hers were Cedar Elm trees with dangerous amounts of Ball Moss covering the branches. We saved them, but it was not easy.
I just think the best treatment for Ball Moss control is physically removing it. When I remove the Ball Moss from a tree it does not recur very quickly in most cases. A byproduct of the physical removal is the smoothing of the bark on the limbs making reinfestation more unlikely. We remove dying and dead limbs further reducing the habitat for the moss. Plus, we often increase light filtration and air flow through the canopy making Ball Moss reinfestation slower. I have many trees that I treated over fifteen years ago that are only just now becoming ready for a touch up treatment. Results vary. This is the best way to treat Ball Moss, in my opinion. It requires an investment, but it is less in the long run and comes with all the other benefits derived of a good class two pruning.