This is a series of posts on what property owners can do in their own yards to improve the health of their trees and landscapes and contribute to the overall health of our urban forest! We’ll add more posts over time, so please stay tuned to this page. If you have questions or would like a certain topic covered, please email the Tallahassee-Leon County Planning Department.

A healthy urban forest has repeatedly been shown to be a vital component of a vibrant and liveable community. Here in Tallahassee and Leon County, trees are increasingly recognized as critical infrastructure that provide benefits to our environment, economy, safety and community. The City and County employ multiple certified arborists to provide professional care for our trees on public property. The densest canopy coverage tends to be in our residential areas, and 70 percent of our urban forest is on private property.

This map shows tree canopy density, the percentage of ground that is shaded by trees. Tallahassee rates very high in canopy density with an overall canopy density of 55 percent.

As a property owner, you play an important role in the long-term health of our urban forest. The care of trees on private property is usually limited by one main factor – cost. Tree work, including planting, pruning and tree removal, can be very expensive, especially as trees get larger. Many common issues, however, can be prevented early in the life of a tree without the need to hire professionals. Locally, trees are very successful at seeding themselves and growing to maturity with no help from us. It’s simply a great environment for lots of different species of trees!

In fact, this region of Florida is one of the most bio-diverse in the nation when it comes to tree species.

Nevertheless, trees growing near homes and businesses do benefit from intervention to ensure that they provide the intended function, whether it be shading our neighborhoods, providing privacy or contributing to a beautiful landscape. Without proper care and maintenance, trees can easily develop problems that negatively affect their health or cause problems with surrounding plants, structures, pavement or utility lines. Preventing common issues early in a tree’s life is the best way to avoid costly problems in the future.

 

 

By Mindy Mohrman, Urban Forester

Hurricane season is upon us and with that comes the necessity of being prepared. In Tallahassee, we live under a beautiful green tree canopy that provides shade, enjoyment and even protection from storms by acting as a buffer that slows down or redirects high winds. Trees are large organisms, however, and we know that they too can be vulnerable to damage from storms and cause damage to their surroundings if they fail. Healthy, well-structured trees endure storms and high winds better than unhealthy, poorly formed trees, so the best thing a tree owner can do is think in terms of prevention well before a storm hits. As you plan year-round care for your trees, remember that the best time to prune trees is during the dormant season or early spring.

While ultimately good for the tree, pruning does create a wound. Winter and early spring are ideal for pruning because insect and decay activity slows down, giving the tree more time to seal the pruning wound before that activity increases for the year. Photo by Mindy Mohrman

In a previous blog post, we discussed structural pruning (add link) to develop strong branch structure. A tree that has been properly pruned throughout its life will be prepared to endure the stress of storm season. Many of us are fortunate to have mature trees on our property, and these trees can also benefit from structural pruning later in life. For large trees, this is best done by a certified arborist who will know how to identify common defects that can lead to weakness and failure and how to mitigate those defects to decrease the risk of failure. Pruning for storm resilience will reduce the foliage mass and weight, especially toward the end of the largest and longest branches or those with defects. This reduces the weight and vulnerability of those branches, while allowing for more airflow through the tree. Dead or hanging branches should be removed as well.

Pruning for storm resilience should result in a tree with well-spaced branches and a low center of gravity. This will spread the wind load throughout the tree so no single point receives the brunt of the pressure. Tall, thin-trunked trees with top-heavy canopies are vulnerable in storms because the top of the tree catches the majority of the wind load.

After a storm, trees may have sustained damage that they can recover from. Immediate hazards should be removed, but for trees that don’t pose a danger, it is wise to wait and watch. High winds can defoliate trees, but this does not necessarily mean that they are dead. Healthy trees will grow new foliage. On the other end of the spectrum, some trees that seem fine after a storm may brown and defoliate in the months afterward. This is common in pines, which may twist in the wind and sustain internal damage that only becomes apparent as the foliage begins to dry out due to interrupted fluid exchange in the sapwood of the tree. Keep an eye on all your trees in the months after a storm for these types of changes.

Losing a tree in a storm, especially if it caused damage to your home or property, often causes homeowners to make fear-based decisions in regards to their other trees or the option to plant new trees. Before making this decision, consider that the vast majority of our trees, especially those native to our area, withstand many storms throughout their lifetime. In fact, a study of Tallahassee’s tree canopy coverage before and after Hurricane Hermine showed no change to overall tree canopy, even though on the ground we witnessed many fallen branches or trees. It is also worthwhile to note that cleanup of wood debris post-storm consists almost entirely of trees and tree parts from private property. Keeping trees strong through proactive care can help homeowners avoid some of these negative outcomes when a storm passes through. Ensuring the trees on our property are healthy benefits our neighborhoods as well as ourselves.

This pine near Lake Talquin began browning a few months after Hurricane Michael and is now completely dead. Removing dead and declining pines is important, because they can be an attractant to pine beetles. Photo by Frank Dietrich

The City of Tallahassee offers resources to assist citizens in planning for hurricane season at Plan for Readiness and Emergency Preparedness (PREP).

---

 

 

By Mindy Mohrman, Urban Forester

Structural pruning is a proactive type of pruning that is performed early in a tree’s life to encourage the development of a strong framework of branches. Establishing good structure when a tree is young requires less corrective pruning later, when pruning wounds might be larger and require more energy from the tree to seal. Effective structural pruning can reduce the potential for the tree to develop the types of defects that result in limb or whole tree failure. For most trees, the goal is to encourage a strong central trunk with well-spaced primary, or scaffold, branches that have strong attachments and plenty of space to grow.

As with any type of pruning, proper pruning cuts that allow the tree to easily seal the wound are essential. Pruning cuts should be made just outside the branch collar, a slightly ridged or swollen area at the base of the branch where it connects to the trunk or another branch. They should neither be completely flush with the trunk, nor leave a stub that sticks out from the tree.

The red line shows where the pruning cut should be made on this yaupon holly, just outside the branch collar. Photo by Mindy Mohrman

Improper pruning cuts can cause lasting damage to the tree by not sealing properly. This provides an open pathway to live sapwood where insect pests or the spores of decay fungi can easily get inside the tree. An improperly sealed pruning wound can lead to decay that spreads throughout the rest of the tree and may shorten the tree’s life or weaken the tree to the point that it may become at risk of failure. Wound sealing products are no longer recommended by arborists, as they can impede healthy scar tissue from sealing the wound. A healthy tree can seal a proper pruning cut without assistance. Obviously, a larger pruning cut takes longer to seal, which is why proactive structural pruning on small branches is so beneficial.

Two examples of poor pruning cuts on the same tree! A stub remains on the cut on the left, while the cut on the right is a flush cut (a pruning cut made behind the branch collar). This eastern red cedar will be unable to effectively seal scar tissue over these wounds. Photo by Mindy Mohrman

Structural pruning should be performed in multiple sessions spread out over the course of several years. Trees need their leaves to produce and store food, so removing too many branches at one time will be detrimental to the tree’s health. As a rule, try to remove no more than 25% of the tree’s crown at any one time and wait at least a year, probably more, before your next structural pruning session. Consider the tree’s shape before you begin and select the branches that will be pruned. For most species, a strong central trunk is the foundation of good tree structure, so competing limbs should be pruned.

 

 

By Mindy Mohrman, Urban Forester

A landscape with mature, healthy trees adds a great deal of value to your home and to your quality of life. Trees are large, living things that grow and change, and as they react to their environment, they sometimes cause damage or injury. Many tree failures are predictable and are caused by common defects that most property owners can learn to recognize on their own. Interpreting the seriousness of these defects is best done by a certified arborist, but you can save yourself trouble and expense down the line if you recognize these defects and understand when to call in a professional. In many cases, there are solutions or treatments that reduce the risk of failure so that the tree does not need to be removed entirely.

The best way to keep trees healthy is prevention, which means noticing potential problems before they become impending problems. Get into the habit of looking up at your trees each week. Familiarize yourself with what they look like throughout the seasons. This will make it easier for you to notice if something changes.

Hanging or Broken Branches

Often, when dead branches fail, they don’t break completely free or they get hung up in the canopy of the tree. Keep an eye out for these; a windy day can dislodge them and send them to the ground unexpectedly.

This branch was connected to the tree relatively low on the trunk, so it didn’t cause damage when it fell. Photo by Mindy Mohrman

Dead or Dying Branches

It’s best to prune dead or dying branches so that the wound can seal properly to protect the tree from insects or decay organisms. If the branches are small and reachable, you can do this yourself with pruners or a hand saw. Larger branches may require an arborist. Either way, proper pruning technique is essential to allow the tree to seal the wound quickly and easily. Loss of a large branch can cause damage to other parts of the tree and leave a major scar that the tree is unable to seal.

This pine has a few dead branches in the lower canopy that could be pruned off. Otherwise, this tree is in fine shape! Photo by Mindy Mohrman

Included Bark

When branches grow at a tight angle in relation to the trunk or another branch, included bark can form. This bark remains between the limbs as they grow, weakening the attachment as the branch gets larger. Trees often split at locations where included bark is present. This can be prevented as a young tree grows through “structural pruning,” a topic I will cover in a future post. If it is present in an older tree, it is something to keep an eye on. If it affects a large branch that may cause damage if it falls, consider having a certified arborist look at it. For a very valuable tree, reduction pruning to reduce the size and weight of the branch or options, such as installing a cable to support the branch, can reduce the risk of that branch failing.

These are extremely poorly formed branch attachments with included bark. Note how the branches originate from the same location on the trunk. Photo by Mindy Mohrman

Cavities and Decay

There are many variables that need to be considered when a cavity or decay is present. The location in the tree, size and depth of the cavity, health of the tree and species can all influence whether the cavity is a major issue or just something to keep an eye on. Some tree species, such as live oak, are very good at compartmentalizing, or sealing off, an area of decay from the rest of the tree. Other species, such as water oak, are poor compartmentalizers, and areas of decay should be taken seriously and inspected carefully. Look for mushrooms on the wood of the tree or out in the yard underneath, which may indicate that the tree’s roots are affected. Various species of wood decay fungus spread differently in trees as well, and a certified arborist can determine whether the species is a cause for concern. If the tree is near a structure or area where your family gathers, it may be best to call in a professional arborist to evaluate.

This lion’s mane fungus tends to be associated with decay in trees. Photo by Mindy Mohrman

Leaning

Trees will often grow with a natural lean as they compete for sunlight with other trees or structures. This is natural, and the tree compensates for this uneven weight distribution as it grows. A lean caused by root damage or soil changes will appear more suddenly and may be something you only notice if you’ve been observant.

Keeping an eye out for these types of tree problems can prevent costly damage, and it keeps your tree in better health too!

---

 

 

By Mindy Mohrman, Urban Forester

In previous blog posts, we’ve discussed the importance of prevention in maintaining the health of your trees. Healthy trees are longer lived and more tolerant of common stressors like injury, drought, environmental changes, pests and disease. The most efficient way to ensure the health of your tree is to begin with the right tree planted in the right place. A tree that has its preferred soil type, sun exposure and space to grow already has its most important needs met. Today, we will focus on other actions you can take to assist your trees in maintaining good health.

Think About the Roots

Tree roots are very close to the surface of the soil, usually in the top 18” with most of the fine, delicate feeder roots in the top 6” where they have access to water and oxygen. This means that any type of grading or compaction of the soil around the tree can cause root damage and loss. Try to avoid disturbing the soil under the “dripline” of the tree, or the area shaded by branches. Staying further away would be even better, as the root system is usually much wider than the canopy.

I love having an excuse to use these pictures! This tulip tree was growing in very wet soil and failed during Hurricane Hermine. This illustrates how massive, but shallow, a tree’s root system can be. Photos by Mindy Mohrman

Mulch

Using mulch under the canopy of the tree is the easiest and most effective action you can take to keep tree roots healthy. Mulch reduces or eliminates competition from other plant roots. Remember, the tree’s roots are very near the surface, so if you have turf grass, they are competing for the same water and nutrients. Mulch holds moisture in the soil longer, reduces soil compaction and provides a healthy environment for other organisms that benefit both the tree and the health of the soil around it. Mulch should be kept to a thin layer of 2” depth and should not touch the trunk of the tree. If you can, extend your mulch out to the edges of the branches or beyond!

This live oak is growing in a grove with several pine trees. Encompassing the entire area in mulch benefits the trees, reduces weeds and competition from turf grass, and keeps lawn mowers away from the trunks of the trees where they may cause damage. For small trees, you can continuously expand the mulch circle as the canopy grows. Photos by Mindy Mohrman

Water

Water is a crucial need for young or recently planted trees, but even a large, mature tree can benefit from receiving additional water during times of drought. We are lucky here in North Florida that we tend to get consistent rain during the hottest months. If you do need to provide additional water, it should be applied slowly so that it has time to penetrate the soil. A back and forth sprinkler for big trees works great for this, as does a hose set to trickle. A tree watering bag that zips around the trunk of the tree is great for small trees, easy to use, and reusable. Search “tree watering bag” online and you should find several styles and brands.

Signs of Stress

Epicormic shoots, or water sprouts, are often a response to stress. The tree produces these in order to quickly put out more leaves to provide food through photosynthesis. These sprouts are unlike a traditional branch that is embedded into the tree with layer upon layer of seasonal wood. Instead, they are stimulated to grow from dormant buds underneath the bark and are superficially attached. They grow very quickly and are often packed tightly together at one location. As they grow, the branch attachments become weaker. They can become quite dangerous if not removed. Water sprouts should be pruned off as needed. In older trees, this is often a sign of general decline.

There are other tree habits that are useful to take note of as you enjoy your backyard. The timing of flowering, new leaf growth and old leaves dropping varies by species and can give clues about the health of the tree. For example, pecan trees are usually the last to leaf out in the spring and the first to lose leaves in the fall. This is normal for this species. Take note of these habits so that you know if something has changed. A tree that drops leaves earlier than usual or is late to leaf out may be experiencing stress.

A thinning canopy can also indicate stress or can indicate that an older tree is experiencing decline. Take extra care to ensure that other factors of stress are minimized. Now is the time to make sure that the tree is mulched and has adequate water.

This live oak is experiencing canopy decline due to age and probable root damage over many years due to construction. Placing trees an appropriate distance from existing roadways can avoid this type of impact. Photo by Mindy Mohrman

Taking steps to provide for your tree’s needs is the best way to ensure a long life, maximize the beauty that it adds to your landscape and maximize its benefits to us, such as clean air, clean water and lower temperatures. Let’s pay trees back for all they do for us by providing good care!

---

 

 

By Mindy Mohrman, Urban Forester

In Tallahassee and Leon County, trees sprout and grow very well naturally. Learning to recognize what is growing in your own yard helps you make decisions that prevent future problems, while also enhancing your landscape.

The data collected for the Urban Forest Master Plan identifies the tree species growing in our community and their respective total of the population. We’ll focus on the most common species for now and branch out from there in later posts!

In this post, I’m showing these trees as seedlings, so you can recognize them when they’re small and pull or relocate them when you see them growing in inappropriate locations BEFORE they require a professional service and costly price tag. If you are relocating the tree, be sure to look up the mature size of that species and replant it in a location that provides the appropriate space.

As you are determining which tree species you’d like to nurture in your landscape, consider the wind resistance rating. The University of Florida has published research that determines the wind resistance of various regional species. After experiencing recent hurricanes, it is critical to work toward achieving a more storm-resilient urban forest. Our goal is to have a high proportion of trees that are rated in the high to medium-high wind resistance categories to improve the overall storm resilience of our tree canopy (download/read PDF).

Invasive Species

First, let’s focus on invasive species. These are plant types that are not native to this area of Florida and have naturally multiplied at such levels that they are actively damaging local ecosystems. They out-compete native species that are much more valuable to our local wildlife and pollinators. They also tend to have low wind resistance due to their predilection for rapid growth. I included a few recently taken photos here, but for more photos and information, including information on managing and controlling invasive species, please visit these great resources.

Florida Invasive Species Partnership
Florida Exotic Pest Plant Council
Florida Invasive Plant Mobile Field Guide

 

 

By Mindy Mohrman, Urban Forester

One of the most frequent tree mistakes I see is perfectly good trees growing in perfectly bad places. The right tree in the right place can add so much to our landscape, but the same tree growing in a location that doesn‘t provide adequate space for that tree at maturity can cause a host of problems to surrounding structures, pavement or utility lines (download and read COT Utilities' "Planting Trees Near Overhead Electric Power Lines").

If you’re planting a new tree, always consider the mature size of that species. You’ll want to look up the “spread,” or canopy width, and find a location that provides that distance from structures, pavement or utility lines. Ask at your local nursery. Many of us here in Tallahassee and Leon County have wooded lots that we cherish. Spend time walking around your property and noting the seedlings that are sprouting on their own. Pull any species you don’t want. Dig up and move trees you do want to locations where they will have adequate space to grow; you’ll thank yourself later when you avoid a costly removal bill for a tree that’s growing into your roof. Here are a few examples of seedlings and small trees that COULD grow up to be good trees but are growing in problematic locations.

As we all practice social distancing, your backyard can be a source of relaxation, learning, and fascination. Also, as part of a community that cherishes its tree canopy, the plants you nurture on your own property can help to improve the health and resiliency of our urban forest!