by Ray Bodrey | Oct 14, 2021
Tree dieback is a complex syndrome and slow developing. Dieback is essentially a process in which trees lose leaves and limbs. This usually occurs as a result of severe stress to the tree’s bark or root system, but could be a result of a declining life cycle.
It’s important to note that there is a significant balance between a tree’s root system and the number of leaves and limbs it can support. For example, if a tree loses part of its root system, possibly due to disease or lawn equipment damage, the tree will forfeit a portion of its leaves. Dieback doesn’t happen overnight, though. It’s a slow process, with larger trees taking much longer time for signs of stress to emerge. However, a large tree root system is very sensitive to damage, whereas a small tree will adapt quickly and is much more resilient to damage. So, what can be done to prevent dieback in trees?
First and foremost, trees, like all living things, have a natural life cycle. Regardless of how you care for your trees, dieback will occur. The most important management measure in extending the life of a tree is to protect the root system and bark.
With each passing year, a tree grows new bark in the rejuvenation process. The bark replacement process inevitably becomes more difficult as the tree gets older and in turn the tree is more and more susceptible to dieback. If the bark becomes damaged, especially later in the tree’s life cycle, then fungi and insects have a much greater chance to cause serious harm. Treating bark damage with a wound dressing to prevent decay is the recommended procedure.
Lichens come in many forms and are commonly blamed for the decline and death of trees and shrubs, however they do not cause harm. Credit. Sydney Park Brown and Joseph Sewards, UF/IFAS.
A common misconception is that epiphytes, such as lichens and Spanish moss, are tree diseases. Epiphytes are known as “air plants” and thrive in the Panhandle. They survive on moisture and nutrients in the atmosphere and are harmless to trees. However, a tree that becomes inundated with epiphytes may be an indicator of excessive soil moisture, which may lead to root rot.
Lawn weed killers can have detrimental effects to trees, even if the application seems to be from a safe distance. When using a weed killer near a tree’s root system, confirm on the label that the product is designed to kill green growth only. It can’t be overstated that excessively fertilizing an old tree will greatly accelerate the decline of the tree. Some may think this will stimulate a tree and extend its life, but instead it will do the opposite. Young trees can tolerate fertilizer applications, as they need crown growth. Older trees will simply become top heavy, and structural damage will likely occur.
Don’t forget, trees need space too. A mature tree forced to occupy a small space will simply not adapt. Be sure to have adequate spacing when planting younger trees and shrubs in the vicinity of older trees. Also, keep your trees pruned away from touching structures and utilities.
Tree dieback is a complex issue to manage. By following these measures, you can help extend the life of your trees and continue to have a picturesque landscape.
For more information on tree dieback, contact your local county extension office.
Please visit Florida Friendly Landscaping, http://fyn.ifas.ufl.edu/, for more information on maintaining your landscape.
For more general information on lichens, please see UF/IFAS EDIS document “Spanish Moss, Ball Moss and Lichens-Harmless Epiphytes” by Joe Sewards and Dr. Sydney Park Brown: https://edis.ifas.ufl.edu/pdffiles/EP/EP48500.pdf
UF/IFAS Extension is an Equal Opportunity Institution.
by Evan Anderson | Feb 27, 2020
This time of year, owners of woody plants might notice that leaf canopies are thin. Fruit and ornamental trees, shrubs, and bushes might have shed some leaves over the winter or thinned out due to disease, cold damage, or other problems. When this happens, it can call more attention to the stems of these plants, which may sport a fuzzy, frilly growth on them. More than once I’ve heard people ask, “What is this growing on my plant and how do I stop it from killing it?”.
Red Tipped Lichen – Image Credit Evan Anderson UF / IFAS Extension
Lichen is the fuzzy growth in question, and the good news is that it doesn’t harm the plant it grows on. Lichen is an organism that’s a combination of fungus and either algae or cyanobacteria. The algae photosynthesizes and produces energy to share with the fungus, which provides protection and support. Thankfully, they’re pretty self-contained, and don’t need to steal nutrients or water from whatever they’re growing on. That means they can grow just about anywhere – on rocks, fence posts, tree bark, or on the ground (if you’ve seen deer moss growing in the woods, that’s a lichen!). Again, they are NOT parasitic and do NOT hurt plants.
Lichen on Tree Trunk. Image Credit Evan Anderson, UF / IFAS Extension
It’s common to find lichens growing in many different forms and colors. One alarmed tree-owner brought me a branch decorated with a round blotch that had a bright reddish edge. A Christmas Wreath lichen had found a home on her tree, and while the red rings it forms may look alarming, they’re just as innocuous as other lichens. There may be multiple forms of lichen growing in close proximity on a branch, as well. Flat, wavy, rippled, filamentous, bushy, and powdery looking lichen might all mix together to make a strange (or beautiful) looking collection on a tree.
by Eddie Powell | Sep 9, 2014
Throughout the year I get calls asking about this mossy-like stuff growing on the bark of trees. For the most part, the calls are in the spring time when people have come out of winter hibernation and see their landscape plants covered with this alien figure. I am here to say that it is not an alien figure, though it may look like it is. These are lichens.
Photo Credit: Eddie Powell
Lichens often get mistaken for some unusual fungus that is killing trees. However, lichens are not single organisms, but rather a combination of two organisms that live together in a mutually beneficial way. There are over 20,000 different types of lichens found in nature. Lichens consist of a fungus and an algae; the fungus is more dependent upon its algae partner which produces enough food for both to survive. Lichens are very different from plants in that they can survive a complete body water loss. During this time, brittle pieces that flake off can later grow into new lichens. When moisture becomes available again, the lichen absorbs water and returns to its fleshy form.
The lichens growing on trees and shrubs are not parasites and do not harm the plants in any way. The lichens use the landscapes as a structure to become established.
There are four different forms of lichens found, crustose (crust-like, growing tight against the substrate), squamulose (tightly clustered and slightly flattened pebble-like units), foliose (leaf like, with flat sheets of tissue not tightly bound), and fruticose (free-standing branching tubes). Colors range from white to gray, green, red, yellow, and black. Lichens commonly found in our area are in the crustose, foliose, or fruticose form, and are white, gray, or gray-green in color.
Because lichens produce chemicals, they have very few natural predators. However, the most serious threat to lichens is air pollution. Most lichens will not grow in a polluted atmosphere and therefore you should be glad to see lichen here or there in your yard, as this is an indication that the air is relatively clean.
by Julie McConnell | Feb 18, 2014
Lichen on trunk of oak tree. Image: Julie McConnell, UF/IFAS
Spanish moss and lichen have earned an inaccurate reputation for damaging trees and shrubs in the Florida landscape. Although they may be found in plants that are in decline or showing stress symptoms, they are simply taking advantage of space available to survive. Both plants are epiphytes and are obtaining moisture and nutrients from the atmosphere rather than from the plants they rest upon.
Spanish moss. Image: Julie McConnell, UF/IFAS
Lichen are more commonly found on plants that are in poor health because they need a plant that is growing slowly and access to sunlight. These conditions can typically be found in thin canopies of trees and shrubs under stress. Although they are firmly attached to the surface of the plant, they are not taking nutrients from the tree or shrub, but rather from the air and other sources such as organic debris and bird excrement. If you find lichen on your landscape plants, look further into what stress factors might be causing the plant to grow slowly such as compacted soil, extreme weather conditions, drought stress, disease or insect pressure.
Spanish moss does not harm trees and many people find it an appealing asset to their landscapes. Common misconceptions about Spanish moss include that the weight causes branches to break and that it is a host site for chiggers. Spanish moss is very light and any additional weight is typically insignificant. Although it may harbor some insects and provide nesting material for birds and other wildlife, Spanish moss in trees is not a site conducive to chiggers because they favor low-lying moist environments.
To read more about Spanish moss, lichens, and other common epiphytes please read the EDIS publication “Spanish Moss, Ball Moss, and Lichens – Harmless Epiphytes.”
