Despite what many people think about lichens their mutualistic relationship can become lopsided and harm your tree if not closely monitored. Is the bark on your trees lacking its usual luster? Have little leafy, cabbage leaf-looking growths have started spreading across the bark? If you answered yes you probably have lichens living on your trees. Although they might look unsightly to some, they’re completely harmless. However, their presence could indicate another tree health issue or nutrient deficiency. Continue reading to learn more about lichens, how to identify different types, and when to call an expert from Cody’s Tree Service, Inc. in Katy, Texas.

What are Lichens?

Lichens are fascinating growths that actually consist of two separate organisms – algae and fungi –operating as one. Their structure results from algae growing in the filaments of fungi. The relationship benefits both organisms, resulting in a lasting symbiotic relationship. The algae create food for the fungi, while the fungi trap moisture for the algae.

Together, they can survive practically anything that comes their way, including extreme temperatures and drought. Since they do not have any roots, they don’t usually impact their tree hosts in any way. In fact, they’re often beneficial to the tree due to their ability to retain moisture and provide protection from the elements.

Lichen Types

Since the fungi type can vary, there are over 17,000 types of lichens found all over the globe. Their appearances can differ considerably as a result, although the ones found most often on trees in Texas look like little leafy plants.

Other varieties may look like moss, mold, or even wool. They don’t just set up camp on living trees either. You can also find lichens growing on your rocks, brick pathways, fallen trees, and many other outdoor surfaces. Once you start looking closely at all the surfaces around your yard, you’re sure to find lichens all over.

While the leafy types usually come in green and gray-green tones, lichens come in many different hues, including yellow, orange, and black. The color usually brightens up a lot when the lichens get wet and then turns back to their natural hue as it dries out.

Why Lichens Grows on Trees

Lichens grow on trees to get ample sunlight and rainfall, giving both organisms what they need to grow and thrive. Since algae produce food through photosynthesis, it greatly benefits from getting as close to the sun as possible. The fungi benefit from the moisture collected off the tree during rainy days.

The lichens do not take any nutrients from the tree itself, so they’re not considered pests. There are no treatments available for lichen as a result. You can usually just let them keep growing, although it’s wise to keep a close eye on their prevalence because lichen overgrowth can sometimes indicate another tree health program.

When to Call Your Arborist for Tree Care Services

An overgrowth of lichens does not indicate causation of your tree’s declining health. In the presence of heavy lichen cover on a sick tree, instead, look to other common culprits that make trees ill. Plant pathogens, insects, and even over-watering or under-watering could instead be causing your tree’s health to decline. If lichens are allowed to take over the majority of the tree’s bark there is a risk of them blocking the exchange of oxygen and moisture barrier. This could contribute to the demise of an already sick tree’s health, but lichens are not pests and they do not require treatment. Whether or not lichens are present on your trees, call a certified Arborist if you have a malnourished or sick-looking tree.


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In order to slow down the growth of the lichens, you have to figure out what’s wrong with your tree. Fortunately, that’s easy to do with an ISA licensed Arborist on your side. You just have to give your tree care specialist in Katy, Texas, a call and they’ll come out to take a look.

At their visit, your arborist will complete a thorough examination of the tree to figure out what it might need. Then, they’ll let you know what treatments could help restore its vigor, including fertilization and proper watering. Through that process, their efforts will help promote healthy canopy growth and reduce the lichens to a reasonable amount.

Contact Cody’s Tree Service Inc. for an Assessment or Service

If you notice that your trees have an abundance of lichens or you just want a professional to take a look, call 281-391-3450 to schedule a visit from your arborist or email us an appointment request. Our team of tree service experts at Cody’s Tree Service has the skills and experience needed to see what’s going on with your trees and restore their health. So, please feel free to reach out whenever you need help caring for your trees.