What is ball moss doing to your tree?
Q: I think few people are aware of ball moss and that only a fraction of them do anything about it. On the internet, you will find that the experts maintain that ball moss is not a parasite, it will not damage trees and it is an aesthetic issue only.
I don't agree that it will not damage trees because I have seen crape myrtles covered with ball moss, and they are obviously stressed. I can barely tell that they are crape myrtles. The crape in my photo had a single ball moss in it two years ago. It now has 40 or 50. In a few years, it will be covered with ball moss if nothing is done. Dozens of crape myrtles in the Clear Lake area have significant infestations of ball moss.
I am afraid that ball moss will become the kudzu of southeast Texas. I appreciate any advice you can give concerning this issue. Roger Gilbertson, Nassau Bay
A: Over the years, readers have asked about ball moss when they’ve spotted the graygreen spiky tufts perched on the branches of live oaks, crape myrtles, vitex and other trees. What is it, and will it harm trees?
Ball moss (Tillandsia recurvata), an epiphytic bromeliad, is a flowering, seed-producing air plant. Like the related Spanish moss, it’s not a true moss.
Yes, experts tell us ball moss is not a parasite that feeds on trees, rather it uses branches for support while absorbing water and nutrients from the air. I’ve heard no one quibble with this,
and I’m convinced because the clumps also live clinging with their pseudo-roots or holdfasts to nonliving structures, including utility lines and screens.
So, if ball moss is not a nutrient-stealing parasite, does it harm trees in other ways? Opinions vary.
Some find the curious tufts decorative and say let them be. While most experts say ball moss does not kill trees, there are those who have determined that when the tufts become extremely dense, they may indirectly stress the tree by shading developing buds or restricting the area for new growth.
I’ve come to agree that too much is not a good thing and base my opinion on observation. Like you, I’ve watched crape myrtles become so heavily clad in the grayish balls that the tree’s foliage and flowers are diminished. I believe that a small amount of ball moss is not harmful, especially to a healthy tree, which, of course, is better armed against any potential pest. So I keep an eye on the health of our crapes and any ball moss that pops up in the big old trees to make sure it doesn’t colonize.
The moderate to heavy ball moss infestations warrant control, not just for aesthetic reasons but because I think dense colonies can affect tree health in the long run.
Matt Petty of Davey Tree’s Houston office has a formula to determine when he takes action. He “divides” a tree into a grid work of 5-foot by 5-foot blocks. If he finds five or more clumps in a section but the rest of the tree is clean, he recommends pruning the area with the ball moss to eliminate the epiphyte. He sprays with Kocide, a copper-based fungicide, if more blocks of the grid have ball moss.
As with all matters in our gardens, awareness is key. Calling attention to dense ball moss in your area gives us another opportunity to identify ball moss and consider whether control is necessary or needed. Field notes are helpful, and I’d like to learn from others who notice a little or a lot of ball moss in their neighborhoods. In researching the latest opinions, I found those expressing no or minor concern to reports from Baton Rouge published to generate awareness and urge action, when needed, as the spiky spheres have been increasingly colonizing in city trees in recent years.
Our warm, humid climate is ideal for ball moss. And wind-blown ball moss seed can jump-start populations elsewhere.
I think the best defense is to keep trees healthy with adequate sunlight, good drainage and an organically enriched soil. Apply an organic fertilizer to encourage new growth. Water slowly and deeply as needed. Mulch to help preserve soil moisture and discourage weeds.
Occasionally check tree canopies. My preferred first go at control: If a few unwanted ball moss tufts pop up in a tree, try knocking them off the branch with jets of water from a garden hose. Destroy the tufts. Or hand pick them, if you can reach them. If the holdfasts have penetrated the bark, scrape the tufts off. Tedious, yes. But it’s easier to take care of a few versus any army.
Prune out limbs with heavier coverage and dead or weakened branches.
Some home gardeners have found a cool-season application of baking soda to be an effective control. Apply at approximately ½ pound per gallon of water. Make sure to saturate the tufts. They won’t disappear overnight. The ball moss dies months after spraying. It will turn dark gray and remain attached to the tree until the holdfasts decay.
Fertilize and deeply water trees after treating.
There are copper hydroxide products that are carefully applied in late winter or early spring. Avoid drift, since it can burn foliage on other plants. The product also can stain.