In the last couple of weeks, I’ve had multiple questions regarding trees and shrubs that aren’t looking too hot. These types of calls are common this time of year – it has gotten hot and dry, and plants have fully emerged from winter, causing issues that have been hiding under the surface during the dormant season to manifest as crown or branch dieback. While there are a wide variety of things that can cause dieback, in most cases a little detective work can help pinpoint the issue. Let’s look at a few of the most common causes of dieback and some corrective measures that may help restore the plants to health.
The first thing to do when you notice a plant in decline is nothing. Don’t try and oversaturate it with water. Don’t run out and dump a bunch of fertilizer around it. Many times, these panic measures exacerbate the stress the plant is already under. Instead, I encourage you to give us a call at your local UF/IFAS County Extension Office. We can likely help identify the cause of the problem through a site visit to your property or by you sending us diagnostic photos of the plant with a description of what’s been going on with it – the more information you can provide about the plant and the management practices it has experienced, the better (you can email diagnostic images/information to d.leonard@ufl.edu).
The most common cause of tree/shrub dieback that I see arises from improper planting practices. Most landscape plants should be planted at or just above the surrounding soil level, preferably where the topmost root arises from the trunk. To accomplish this, planting holes should be dug slightly shallower than the rootball’s height and about twice as wide. Planting any deeper than that is probably too deep and can cause problems like trunk and root decay, which lead to crown dieback. Unfortunately, once a plant is planted too deep, it cannot be corrected other than digging up and replanting at the proper depth, which may or may not be possible depending on the size of the tree. Another common issue that can arise after planting is girdling roots. This occurs when plants are grown in plastic containers and develop a root system that circles the inner wall of the pot. If not trimmed, the plant’s root system will continue to grow in this manner, eventually encircling the plant’s trunk, cutting off water and nutrient flow, and leading to crown dieback. Fortunately, this condition can be prevented by cutting, removing, or redirecting these roots at planting.
The next most common cause of plant dieback occurs due to soil disturbance by people. It’s easy to forget but the root zone of trees and shrubs can reach out several times farther than the plant is tall and is easily damaged. Disturbances to the root zone from digging or trenching near trees or compaction from prolonged vehicle travel over the area cause damage that might be slow to appear but can lead to plant decline. If you are doing construction or building near a shrub or tree, try to keep digging machinery as far out of the root zone as possible and avoid repeatedly parking or driving vehicles over the root zone area. Like below ground root damage, trunk damage that occurs from injury by string trimmers, mowers, or animal feeding activity can all disrupt the flow of water and nutrients in plants and prove deadly. There is no cure for this type of damage, so employing physical barriers to prevent damage is key.
The last major stress is environmental in nature and is caused by a water imbalance – either too much or not enough. Dry soil conditions during the planting and establishment phases (first several years after planting) should obviously be avoided if possible – keeping the developing rootzone moist and allowing plant roots to establish in their native soil is critical. Too much water can also cause problems for trees planted in poorly drained soil. Excessive moisture leads to root diseases, which ultimately presents as dieback in the canopy. If planting in an area that tends to stay wet, select a species of plant adapted for that sort of site – some species are more tolerant of “wet feet” than others. While many people expect disease and insect damage to be the cause of an unhealthy plant, they’re often not the biggest culprit and, if they occur at all, are generally secondary to one of the above issues.
The crown of a tree is the leaf bearing twigs and branches and the spreading green foliage that we see. A heathy, full crown is a good indication of a healthy and vibrant tree. The crown and the foliage it supports is the energy collector and the center for photosynthesis, which is how the tree produces the energy it needs to live. For a tree to live and thrive, a full crown of leaves is essential, and an unhealthy and thin crown is an indicator the tree has issues. Crown dieback is often not noticed until it is relatively severe and at that point it can be too late. If a tree drops below a certain percentage of live crown it can no longer support itself and continues to decline. The good news is that if you notice your tree is starting to show signs of crown thinning and dieback you can likely intervene to improve its health or diagnose a problem early.
Tree Showing crown dieback, note the dead branches and lack of foliage on the outer branch tips. Photo Credit-Ian Stone
Crown dieback, which is also referred to as crown decline, is a progressive issue that starts small and can progress to the point that only small sparse areas of foliage are left. It is a tree’s response to various stressors, including environmental conditions and severe rot/decay. As a response to severe stress, the tree begins to abort part of the leaves and some of the small branch tips. If the stress continues to worsen, the tree will continue to abort more of the crown, producing progressively more dead wood. The tree is essentially trying to prune itself back to a manageable level of foliage based on the stress it is encountering. This can occur in both small, young trees and mature, established trees. A variety of conditions cause the stress that begins this process. For instance, you may notice crown dieback in young trees planted in compacted urban conditions such as parking lots and paved areas. Trees in these conditions experience stress from the compacted soil and encounter subsequent issues with water and nutrient stress. Large mature trees in an area that experienced recent construction may also exhibit dieback, especially if buffers and setbacks are not maintained or significant fill dirt is brought in. Issues from root disturbance and compaction cause stress and root dieback, which in turn causes visible crown dieback. Additionally, trees that are experiencing rot, decay, and other vascular disease issues will often begin to exhibit dieback. As the rot or vascular disease progresses, the tree is less able to transport water to the crown, which results in the crown dieback that can be seen as the crown thins. Often, in cases of rot, crown dieback will be the primary visible symptom that rot is occurring, as the rot can be concealed deep in the tree. While multiple stressors can be the cause of crown dieback, it is a clear indicator a tree is stressed and in trouble. If this condition goes unnoticed, it can progress past the point that the tree can be saved. However, if noticed and caught early, good tree care techniques can be applied that may restore the tree to heath. In cases of severe rot and decay, having the tree examined may prevent structural failure of a tree exhibiting crown dieback.
If you have a tree on your property that is exhibiting crown dieback, it is a good idea to have the tree examined by a professional to determine the extent and nature of the issue. Key signs of dieback are bare branch tips and dying foliage during spring and summer. It is natural to have some dead wood in a tree, but extensive dead wood around the entire perimeter of the crown is a cause of concern. With good diagnosis, the proper tree care techniques can be applied to help a tree recover. Waiting and hoping a tree with crown dieback will recover on its own is not a good course of action. Recognizing crown dieback and taking early action is the key to success. Contacting a Certified Arborist (www.treesaregood.org ) is a good step in getting an opinion on the extent of dieback, if the tree is recoverable, and how to best address the issue. You can also contact your local County Extension Office or Florida Forest Service County Forester for assistance.
Our winter season is a good time to install many trees and shrubs. Here is a basic review of a few planting practices to make sure that your new plants get off to the good start.
Florida has a diverse array of birds. Warblers, raptors, shorebirds, and more may be spotted now in North Florida. Your yard or landscape can serve as an ideal habitat for wildlife, particularly birds. Even a modest quarter-acre plot can be intentionally designed to offer a supportive environment for a variety of birds. Transforming your backyard into a sanctuary for birds might allow you to witness these fascinating visitors firsthand.
“Rudbeckia’ photo by UF/IFAS
CONSIDER NATIVE PLANTS
Bring a touch of local charm to your yard by choosing native plant species whenever you can. Native birds have a natural connection with these plants, having evolved alongside them. What’s more, landscapes featuring Florida-native plants demand less attention and resources compared to those with non-native varieties. Native plants are well-suited to the local soil conditions, usually need less fertilizer, and boast better resilience against common pests and diseases. Embrace the beauty of native flora while making your yard a low-maintenance haven for both birds and nature.
“Snags” photo by UF/IFAS
MAKE SAFE COVER AVAILABLE
When trees face disease or reach the end of their life, think about leaving them as standing snags—imperfect yet invaluable shelters for wildlife to feed and nest. Additionally, creating a couple brush piles, especially near other plants, offers fantastic cover and feeding spots for birds. These piles not only provide a feeding opportunity for our feathered friends but also act as protective hideouts in open spaces. Embrace the natural cycle by turning aging trees and brush into welcoming havens for local wildlife.
INCLUDE A VARIETY OF LAYERS
Birds take to the skies, and for a thriving habitat, it’s essential to have various levels in your environment—tall trees, medium-sized trees, high and low shrubs, and groundcover. The more diversity, the better, as different bird species rely on different layers for their needs.
Tall trees play a crucial role, creating a sort of continuous woodland environment where birds can gracefully move from tree to tree. The choice of trees and shrubs you plant significantly influences the overall health of your landscape. Opt for species that suit your specific site and soil conditions to ensure a welcoming and supportive environment for our avian friends
“Birdbath” photo by UF/IFAS
ADD A WATER SOURCE
Water is a vital ingredient for wildlife environments, and birds reap the rewards from any water source you offer. It can be as easy as placing a shallow dish or bowl filled with water or adding a small fountain to your outdoor space. Just remember to switch out the water regularly to thwart mosquito breeding and ensure a clean and refreshing oasis for our feathered companions.
UTILIZE BIRD FEEDERS
A delightful way to connect with nature and witness birds up close is by using bird feeders. Not only does this provide an opportunity for observation, but it also supplements the natural food sources available to birds near your garden. For those interested in incorporating bird feeders, it’s important to remember proper care and maintenance. Neglected feeders can become breeding grounds for mold and bacteria, posing a risk to the health of the birds. A recommended practice is to clean feeders at least once every 1-2 weeks, or more frequently in wet or humid conditions, using a diluted bleach solution. For nectar feeders, a simple wash with soap and hot water is sufficient. Always ensure the feeders are thoroughly dry before refilling them with bird feed. This way, you not only create a welcoming space for our feathered friends but also ensure their well-being through responsible feeder care.
WINTER WANDERERS
Creating a bird-friendly backyard in North Florida is not only a satisfying project but also a meaningful way to help protect our feathered friends. By making smart choices in your landscaping, you can turn your outdoor space into a welcoming sanctuary for birds. The benefits are twofold: you get to enjoy the colorful variety of bird species visiting your backyard while also contributing to the conservation of biodiversity in the area. Let your backyard showcase the harmonious relationship between humans and nature’s nomads. For tips on landscaping that supports birds, reach out to your local county extensions office.
Florida’s natural areas—a great source of pride and enjoyment to its citizens—provide recreation, protect biodiversity and fresh water supplies, buffer the harmful effects of storms, and significantly contribute to the economic well-being of the state. Unfortunately, many of these natural areas can be adversely affected by invasive plant species. An estimated 25,000 plant species have been brought into Florida for use as agricultural crops or landscape plants. While only a small number of these have become invasive, Chinese tallow (Triadica sebifera) is one of them.
As the trees begin to turn various shades of red, many people begin to inquire about the trees. While their autumn coloration is one of the reasons they were introduced to the United States, it took years to realize what a menace the trees become. Triadica sebifera, the Chinese tallow is locally referred to as popcorn tree due to the appearance of the developing seed heads, white three-chambers seeds covered in a fatty wax. It was introduced to Charleston, South Carolina in the late 1700s for oil production and use in making candles. However, the seeds are also tasty snacks for birds and can float long distances in the water, enabling it to spread to every coastal state from North Carolina to Texas, and inland to Arkansas. In Florida it occurs as far south as Tampa, displacing other native plant species in those habitats. Therefore, Chinese tallow was listed as a noxious weed by the Florida Department of Agriculture and Consumer Services Noxious Weed List (5b-57.007 FAC) in 1998, which means that possession with the intent to sell, transport, or plant is illegal in the state of Florida.
Fall color of Chinese tallow
Individuals can help mitigate the problem of Chinese tallow trees in Florida’s natural areas by removing them from their property. Mature trees should be felled with a chain saw by the property owner or a professional tree service. The final cut should be made as close to the ground as possible and as level as possible to facilitate application of an herbicide to prevent sprouting. Stumps that are not treated with an herbicide will sprout to form multiple-trunked trees. If it is not objectionable for dead trees to be left standing, certain herbicides can be applied directly to the bark at the base of the tree (basal bark application).
Herbicides that contain the active ingredient triclopyr amine (e.g., Brush-B-Gon, Garlon 3A) can be applied to cut stumps to prevent re-sprouting. The herbicide should be applied as soon as possible after felling the tree and concentrated on the thin layer of living tissue (cambium) that is just inside the bark. Herbicides with the active ingredient triclopyr ester can be used for basal bark applications. Only certain triclopyr amine products may be applied to trees that are growing in standing water. If trees are cut at a time when seeds are attached, make sure that the material is disposed of in such a way the seeds will not be dispersed to new areas where they can germinate and produce new trees.
Space in a landscape left after removal of Chinese tallow can be used to plant a new native or noninvasive tree for shade, or some other landscape purpose. Although Florida is not known for the brilliant fall color enjoyed by other northern and western states, there are a number of trees that provide some fall color for our North Florida landscapes. Red maple, Acer rubrum, provides brilliant red, orange and sometimes yellow leaves. The native Florida maple, Acer floridum, displays a combination of bright yellow and orange color during fall. And there are many Trident and Japanese maples that provide striking fall color. Another excellent native tree is Blackgum, Nyssa sylvatica. This tree is a little slow in its growth rate but can eventually grow to seventy-five feet in height. It provides the earliest show of red to deep purple fall foliage. Others include Persimmon, Diospyros virginiana, Sumac, Rhus spp. and Sweetgum, Liquidambar styraciflua. In cultivated trees that pose no threat to native ecosystems, Crape myrtle, Lagerstroemia spp. offers varying degrees of orange, red and yellow in its leaves before they fall. There are many cultivars – some that grow several feet to others that reach nearly thirty feet in height. Also, Chinese pistache, Pistacia chinensis, can deliver a brilliant orange display.
There are a number of dependable oaks for fall color, too. Shumard, Southern Red, and Turkey are a few to consider. These oaks have dark green deeply lobed leaves during summer turning vivid red to orange in fall. Turkey oak holds onto its leaves all winter as they turn to brown and are pushed off by new spring growth. Our native Yellow poplar, Liriodendron tulipifera, and hickories, Carya spp., provide bright yellow fall foliage. And it’s difficult to find a more crisp yellow than fallen Ginkgo, Ginkgo biloba, leaves. These trees represent just a few choices for fall color. Including one or several of these trees in your landscape, rather than allowing the popcorn trees to grow, will enhance the season while protecting the ecosystem from invasive plant pests.
For more information on Chinese tallow tree, removal techniques and native alternative trees go to: http://edis.ifas.ufl.edu/ag148.
