You may have seen the billboards around town asking that you "Bag the Ball Moss!" and wondered: What the heck is ball moss?

Quite simply, it's moss that grows in a roundish, ball shape. 

The problem: There's just too much of it.

The proliferation of ball moss is hurting mature oaks and is making them more susceptible to diseases and insects, according to Chris Cooper, a Baton Rouge Green program specialist and coordinator of urban and community forestry.

“Basically, ball moss is overstaying its welcome,” Cooper said.

He said ball moss can be particularly aggressive and harmful on small trees, especially those that may already be under stress.

“In the urban environment, the majority of our trees are experiencing stress in some form or fashion,” Cooper said.

Limbs heavily infested with ball moss may break off under the added weight, especially during rains or windstorms.

Usually these fallen branches are dead or dying, leading some people to conclude the ball moss has killed the limbs. But ball moss and its cousin, Spanish moss, are not parasites. Ball moss photosynthesizes its own food and does not deprive its host of a significant amount of additional water. Seeds of ball moss are spread by wind, rain and animals.

Cooper said branches usually die from lack of sunlight, which can be caused by an infestation of ball moss.

“Once (ball moss) populations get over 50% canopy coverage in an individual (tree), it can be almost impossible to recover from and may reduce the tree’s photosynthetic ability to a point where dieback occurs,” Cooper said.

A tree that is stressed or sickly may be more susceptible to infestation, causing further decline of the tree, he said.

Ball moss can survive on utility lines, fences or rocks, and will take about three years to mature and flower and then will bloom for about the next seven years.

You can spot ball moss in the upper crown of the tree. It grows well in areas with low light, little airflow and high humidity, an environment commonly provided by southern shade trees, often the southern live oak.

It looks like gray clumps on branches of trees and bushes.

The “Bag the Ball Moss!” campaign, promoted on billboards donated by Lamar Advertising, is designed to help property owners spot it and help contain it to prevent further spread.

Here's how to treat it:

1. Remove it by hand or with a focused stream from a garden hose. (Caution: Using a pressure washer will damage the bark and cause significant injury to the tree if used incorrectly). If the moss is out of reach from the ground, call a tree service professional. 

2. Once removed, bag the ball moss before discarding it to prevent further spread. Removal of dead tree limbs after the ball moss has been discarded also is recommended.

For information on how to treat ball moss, visit

This information is presented in conjunction with Louisiana Master Naturalists of Greater Baton Rouge, which seeks to advance awareness, understanding and stewardship of the natural environment. For more information, email