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. Which means, they are almost always harmless to the tree.
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. That means the ultimate control practice is to have a healthy tree, and in the GardenLine Family that means follow the Deep Root Feeding tip sheet from our webpage or even in my book.
Currently there is no chemical control for lichens. In the past, we've always recommended copper-based fungicides such as Kocide. We've also found that any banner-based fungicides (also known as Propiconizol - PPZ) also work to diminish the amount of Lichens. Research has also shown that all of these fungicides can wash off very easily after a rain or even an irrigation cycle. So, when using these fungicides for Lichen control, just make sure that it's on a dry period of two days or more. .
Ball Moss (Tillandsia recurvata)
Now, while Lichens are often harmless, Ball Moss is often more detrimental. Ball moss is the grayish-green "pincushion-like" or tufted growth seen on the bark of a number of Texas shade trees. Or for those people who scuba dive or snorkel in the Carribean, it also looks like sea urchins on the tree. 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. In fact, it's the same fungicides as listed above for Lichen control. Kocide or any Banner-based Funcide (those with Propiconizol - PPZ).
When there is only a light infestation of ball moss present, just take good care of your trees by following the Deep Root Feeding techniques as listed above in the previous tip sheet 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 Fungicide.(Best applied February through June).
3. Deep Root Feed following the rules of the previous tip sheet.
4. Re-treat with fungicide in 6 months if the ball moss is still active.
When controlling ball moss using Kocide or PPZ, 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 June. This insures that the fungicide is on the ball moss and waiting to be absorbed into the moss with the next spring rain. 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.
Until next issue, here's to Great Gardening from the GardenLine, heard exclusively, 6-10 a.m. Saturdays and 7-10 a.m. Sundays, only on NewsRadio 740 KTRH.
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