PAnews.com, Port Arthur, Texas

Garden

March 24, 2011

Ways to control mistletoe to moss

BEAUMONT — We routinely get calls concerning lichens, ball moss, and mistletoe found growing in our trees. The following information was taken from an article written by Dr. Jerry Parsons.

Ball 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 and ball moss, 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.  Its feeding structures grow into the tree and it feeds from the sap flow. Mistletoe is spread by birds feeding on the berries and spreading the seed in their droppings onto other limbs. Mechanically removing the mistletoe from the tree is the only control method currently recommended. 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  mistletoe roots are 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 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.

Ball moss is the grayish-green tufted growth seen on the bark of a number of trees. Ball moss 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.

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:  The first step is to prune outseverely infested or weakened branches.  You can then try to get control by using sprays such as Kocidethat have copper as an active ingredient.  It will take anywhere from 6-12 months for the ball moss to die out. 

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.

Micah Meyer is county extension agent-horticulture of the Texas AgriLife Extension Service in Jefferson County. He can be reached at 409-835-8461 or cmmeyer@ag.tamu.edu.

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