Lichen might be cute and fuzzy ——But lichen may signal more serious problems for plants. In the winter months, gardeners and homeowners are more likely to notice the grayish green crusty or mossy-looking growth on the stems and branches of trees and shrubs. This common organism, known as lichen (pronounced “liken”), is a primitive form and is the result of two different organisms, an algae and a fungi, living together.
Lichens will grow on almost anything that sits still long enough, which includes fence posts, rocks, and even the ground. Often times when we find lichen on tree trunks and branches, it may simply be a sign that that particular plant is naturally slow growing, or that it is an older plant that is not growing at a fast rate.
Lichens do not harm the plants they grow on, but often plants that are struggling will be covered with them. When lichen are found growing prolifically on a plant that also has lots of dead twigs and branches and that produces few, undersized or off color leaves, it is usually a sign that something more serious is going wrong.
Lichen are rarely found on healthy, fast growing trees and shrubs because they are always shedding bark, making it difficult for lichen to attach to them. If you have a tree or shrub that has recently been inhabited by lichen, there is a very good chance your plant is not healthy. In most cases, the plant’s problem is in its root system. Because roots are rarely seen it is easy to overlook how important they are to plant growth and health, when in fact the root system is the most important part of any tree or shrub. Roots provide plants with the water and nutrients they need to grow and survive. Just consider, a plant can lose all of its leaves and still recover, but if it loses all, or even most of its roots, it will die.
There are several reasons lichen may appear on the branches and trunk of trees and shrubs, roots being one of them. Roots may be growing in oxygen deprived soils due to being in a water logged area or compacted soils. Driving under a shade tree or next to a tree will compact the soil to the point of squishing all the oxygen out of the soil in that area. Even continuous walking on a path or the path the dog takes around the fenced in yard compacts the soil so that no grass will grow in those areas. The Ph or nutrition of the soil may be so bad that the trees of shrubs starts to fail. A soil test will tell you if that is a concern.
Mulching trees and shrubs, sometimes to the drip-line is always a wise investment to the health of your trees and shrubs. This will remind you not to park near the tree. Mulching will also improve the soil conditions under the mulch over a period of time and hold moisture for optimum growing.
There may have been damage to the trunk and/or branches as well. The tree may have been hit by lightning, weed eater, lawn mower or have been climbed too many times causing branches to break. There may be insects, bores, or disease in the tree or shrub making it not grow at an optimal rate or health which in turn encourages the lichen to find a new best tree or shrub.
The trick is figure out the reason the tree or shrub is not doing as well as possible and fix the underlying problems when possible. The first thing I would do is check the soil for compaction and /or water, look at the branches for wounds and insects. If nothing seems to be out of place, then take a soil sample and bring it to the office. There is some reason that tree or shrubs does not like that spot, just be observant. Adding fertilizer to a plant that is not doing well is only going to make it more stressed and do worse.
If you have questions about what is going wrong in your lawn, garden or landscape contact your local Cooperative Extension Office. In Bladen County, call 910-862-4591, bring samples to our office at 450 Smith Circle Drive in Elizabethtown or visit online anytime at http://bladen.ces.ncsu.edu.
This story was revised by Nancy Olsen, an agent with the Bladen County Cooperative Extension Office.