What is Crown Dieback in Trees?

What is Crown Dieback in Trees?

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.

Video: Tree Planting Basics

Video: Tree Planting Basics

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.

Celebrate Trees in January

Celebrate Trees in January

The best time to plant a tree is twenty years ago.  The second best time is Arbor Day 2024.  Florida recognizes the event on the third Friday in January, so the next one is January 19, 2024.

Arbor Day is an annual observance that celebrates the role of trees in our lives and promotes tree planting and care.  As a formal holiday, it was first observed on April 10, 1872 in the state of Nebraska.  Today, every state and many countries join in the recognition of trees impact on people and the environment.

Trees are the longest living organisms on the planet and one of the earth’s greatest natural resources.  They keep our air supply clean, reduce noise pollution, improve water quality, help prevent erosion, provide food and building materials, create shade, and help make our landscapes look beautiful.  A single tree produces approximately 260 pounds of oxygen per year.  That means two mature trees can supply enough oxygen annually to support a family of four.

The idea for Arbor Day in the U.S. began with Julius Sterling Morton.  In 1854 he moved from Detroit to the area that is now the state of Nebraska.  J. Sterling Morton was a journalist and nature lover who noticed that there were virtually no trees in Nebraska.  He wrote and spoke about environmental stewardship and encouraged everyone to plant trees.  Morton emphasized that trees were needed to act as windbreaks, to stabilize the soil, to provide shade, as well as, fuel and building materials for the early pioneers to prosper in the developing state.

A newly planted tree with water retention berm.
A planted tree with water retention berm. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

In 1872, The State Board of Agriculture accepted a resolution by J. Sterling Morton “to set aside one day to plant trees, both forest and fruit.”  On April 10, 1872 one million trees were planted in Nebraska in honor of the first Arbor Day.  Shortly after the 1872 observance, several other states passed legislation to observe Arbor Day.  By 1920, 45 states and territories celebrated Arbor Day.  Richard Nixon proclaimed the last Friday in April as National Arbor Day during his presidency in 1970.

Today, all 50 states in the U.S. have an official Arbor Day, usually at a time of year that has the correct climatological conditions for planting trees.  For Florida, the ideal tree planting time is January, so Florida’s Arbor Day is celebrated on the third Friday of the month.  Similar events are observed throughout the world.  In Israel it is the Tu B Shevat (New Year for Trees).  Germany has Tag des Baumes.  Japan and Korea celebrate an entire week in April.  Even, Iceland one of the most treeless countries in the world observes Student’s Afforestation Day.

The trees planted on Arbor Day show a concern for future generations.  The simple act of planting a tree represents a belief that the tree will grow and provide wood products, wildlife habitat erosion control, shelter from wind and sun, beauty, and inspiration for ourselves and our children. 

“It is well that you should celebrate your Arbor Day thoughtfully, for within your lifetime the nation’s need of trees will become serious. We of an older generation can get along with what we have, though with growing hardship; but in your full manhood and womanhood you will want what nature once so bountifully supplied and man so thoughtlessly destroyed; and because of that want you will reproach us, not for what we have used, but for what we have wasted.”

 ~Theodore Roosevelt, 1907 Arbor Day Message

Native Fruit Trees – The Common Persimmon

Native Fruit Trees – The Common Persimmon

The Common Persimmon, Diospyros virginiana, is a southern native small to medium fruit tree that is becoming more popular for homegrown fruit. The bark is grey or black and forms chunks or blocks that give it a checkerboard look. Fall color can be a spectacular red in USDA hardiness zones 4 through 8b. It is well adapted to cities but requires fallen fruit maintenance and wildlife control. Its mature height can be 40 to 60 feet, with branches spreading from 20 to 35 feet and a trunk two feet thick, but it is commonly much shorter in landscapes. The trunk can be a single form or multiple trunks and the species tends to form colonies. The leaves are alternate, simple, and a rich green color. The leaf margins can be entire or somewhat serrated. The funnel-shaped flower has four petals and ranges in color from white to cream to gray. 

Full Persimmon Tree, UF
Tree Bark, UF

The Common Persimmon fruit is smaller than a ping-pong ball. This round fruit possesses an orange to reddish-purple color, with a size of 1 ¼ inches across. The flavor is more fermented and sugary-sweet. In Florida, the harvest season is from late August to early November. Fruit do not ripen at the same time. When ripe, the fruit turns from green to burnt orange. They also fall from the tree. The fruit is soft, sticky, and very delicious, but it needs to be separated from its skin and seeds before being used in recipes. They can be eaten when fully ripe and can also be pureed, dried, and used in preserves, chutneys, quick breads, puddings, pies, and sweet and savory dishes. The fruit is very favored by wildlife. Persimmon fruit is an essential food source for songbirds, turkeys, and small and large mammals.

Common Persimmon Fruit, UF
Common Persimmon Fruit, UF

Common persimmon prefers moist, well-drained, bottomland or sandy soils but is known to be very drought- and urban-tolerant. It is a fantastic tree in its adaptability to site conditions, including alkaline soil. It is commonly seen as a volunteer tree in old fields but grows slowly on dry sites. Its fruit is an edible berry that usually ripens after frost. Some cultivars do not require the frost treatment to ripen. Persimmon fruit is hard and astringent when unripe. Most American cultivars require both male and female trees for proper fruiting.

Besides fallen fruit maintenance, persimmon maintenance is easy and is suggested that it persimmon should be planted more often. Due to a coarsely branched root system, transplanting is difficult. The trees should be balled and burlapped when young or grown from containers. The wood from the tree is used for golf club heads because it is tough and almost black.

Common persimmon is troubled by a leaf-spot disease in the South. This disease causes black spots on the leaves and premature defoliation in August in the North and September in the South. The tree will not die from the disease. It is also susceptible to a vascular wilt, which can devastate established trees. There are no severe insect pests fort his native fruit tree, except occasional caterpillars.

For more information, please contact your local county extension Office.

ENH390/ST231: Diospyros virginiana: Common Persimmon (ufl.edu)

The Summer Stress is Starting to Show in Trees

The Summer Stress is Starting to Show in Trees

It has been a hard summer climate wise and as we go into fall it is nice to start getting some relief from the heat. As the heat tones down, we are still facing a drought, which is not as severe as areas to our west but is still significant across much of the Panhandle. In our tree cover, the stress from the harsh summer this year is starting to show. You can see it in trees around the area, and it particularly seems to affect certain trees and conditions more than others. Where you are starting to see it most is in our ever-present pines, which make up the majority of our forest and tree cover in our region. If you keep a look out you may notice some pines in the areas with yellowing or brown needles or that are losing their needles. Those are clear signs of a possible bark beetle attack, which is a common issue when pines are stressed or damaged. Trees planted in the last year that are not yet fully established often show stress in a hot dry summer like this year. Even older and well-established trees in areas are showing some signs of stress from the hot dry conditions we have had this summer.  Some trees are less adapted to dryer areas and when planted off site can experience more stress in dry conditions. If you look around across the Panhandle right now you can see clear signs of stress in some trees. It becomes more evident in late summer and early fall as the accumulated stressors of summer push trees into physiological conditions that cause stress responses. The big question is what to do if you notice a landscape tree that is exhibiting signs of stress, particularly drought stress.

Pine damaged by construction equipment. Barking injuries like this can encourage bark beetle attacks. Photo Credit: Ian Stone

For pines the issue is likely to be bark beetles, of which there are several types. All pine bark beetles are native to our area and the degree of damage they do varies by species and conditions. The issue with stressed trees is that most bark beetles attack those trees. When a hot dry summer occurs bark beetle activity increases as the stressed trees become less able to fend off attacks by these beetles. Unfortunately, when bark beetles attack a pine in an area the best answer is prompt removal and disposal of the infected tree material. To protect high value trees in an area where bark beetles are active there are some injection pesticides that can prevent infestation, but once a tree has been infested and begun to show symptoms little can be done to bring it back. When bark beetles attack a stressed pine, most are effectively finishing off a tree that may have died regardless. The key is to prevent them from spreading to other pines in the area or attracting them to a stressed tree in an area. With trees already stressed in our area the big prevention option is not to damage or stress any pines already on the landscape. Most pine bark beetles are attracted to trees by chemicals in pitch and resin given off by wounds or damage. Often the stress from new landscaping projects or construction around pines can cause several to succumb to bark beetles. Your best prevention is to keep equipment well away from the tree and avoid damaging or injuring the tree, especially scraping areas of bark off. Larger and older trees can be vulnerable, as well as overcrowded trees that are too dense or overtopped by others. As the cooler weather approaches bark beetle activity should decrease along with the risk of losing a pine to these pests.

Recently constructed sidewalk. Construction activities extended well into the root zone of the tree, which can cause stress and damage. Photo Credit; Ian Stone

For other trees there are additional precautions that can be taken to lessen the potential that a tree will succumb to drought and other stress. Newly planted trees or those established in the last several years are particularly at risk and should be watered regularly during this dry period. Until rains return, a good method of slowly applying water deeply to the root zone is best. Properly applied mulch can help keep the soil cooler and moist around a newly planted tree. Drip irrigation, soaker hoses, and similar methods are best, and a method that specifically applies water slowly to the tree’s root zone gives the best results. Watering your lawn does not supply sufficient water to landscape trees, especially in drought conditions. Lawn irrigation is designed to apply irrigation needed to the top portion of the soil that is available to the grass. Trees have completely different requirements and need different watering methods and amounts. If you don’t have dedicated irrigation available and you have a tree that needs water, you can use irrigation donuts or bags. These are often a good solution for a tree that needs watering temporarily. Once a tree is well established it usually can withstand even severe drought, but during the establishment phase paying attention to water needs is critical in a summer drought like we have had.

Large established trees are also not immune from the heat and dry conditions that have plagued the Panhandle this summer. Usually when conditions change these trees recover but may abort some branches or exhibit some leaf drop while stressed. Leaf drop is a phenomenon that can occur when deciduous trees are stressed. It is a method of conserving water needs by reducing the leaf demand. Usually, the tree will recover and leaf out again fine next year. A tree may abort some branches or have some branch tips die back to make it through a rough period. Trees that are overcrowded, overtopped, or have other issues are the most at risk from environmental stress. This is why good tree selection along with proper tree care and maintenance is essential. When a hot dry summer like we have had comes along well cared for and maintained trees do best. Trees that prefer more moisture like bald cypress, red maple, sycamore, and some oaks can be planted in dryer sites, but when a severe drought comes along they often don’t have the ability to handle the moisture stress that trees adapted to dryer sites can. This is why site selection is so important, it is when we have extreme conditions that off site plantings typically suffer the worst and those can be larger more established trees.

With the cool weather hopefully we will get a reprieve and some rain soon. Given that fall is one of our dryer periods it may be likely that drought conditions could persist until early winter. Good care and tree maintenance is essential to getting your trees through stressful periods like this summer. For younger trees watering and care is essential while they get established. For older established trees avoid doing any construction or other disturbing activities around them until conditions improve. If you have trees that are exhibiting signs of decline or pest attacks call your local extension office or Florida Forest Service County Forester office. With any luck, colder weather with winter rains will be here soon and trees in our area will recover over the dormant period.

Screen Trees for Privacy and Noise Reduction

Screen Trees for Privacy and Noise Reduction

Sometimes we just need a little privacy. This is especially true if you live on a busy road or just have annoying neighbors. There are a few things to consider when selecting a screen tree: 1) full-grown size; 2) speed of growth; and 3) aesthetics. With these three factors in consideration, let’s review some screen options for different situations.

Pineapple guava
Pineapple Guava (Acca sellowiana) hedge. Photo Credit: Daniel Leonard, University of Florida/IFAS Extension – Calhoun County

Pineapple Guava (Acca sellowiana)

At one time this shrub was hard to find, but it is slowly becoming more available. Pineapple guava is native to South America, but it adapts well to the Florida Panhandle. This plant can reach 10 to 15 feet in height with an equal spread and has a moderate rate of growth, so it’s a great choice when you just need a small screen. Pineapple guava is moderately salt-tolerant and does well in coastal landscapes. As a bonus, the flowers and fruit are edible. It’s hard to find a more aesthetically pleasing large shrub. Pineapple guava is evergreen with leathery green leaves that have grey undersides. This plant can be grown as a large shrub or pruned to be a small tree.

'Emily Bruner' Holly
A large ‘Emily Bruner’ holly at the Santa Rosa County Extension Office. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

‘Emily Bruner’ Holly (Ilex x ‘Emily Bruner’)

‘Emily Bruner’ holly is a cross between the Chinese holly (Ilex cornuta) and the lusterleaf holly (Ilex latifolia). This evergreen shrub has glossy green leaves. It has a pyramidal growth habit and is listed as reaching 15 to 20 feet tall by 5 to 8 feet wide, however the specimen at the Santa Rosa County Extension Office is about twice that size. ‘Emily Bruner’ holly prefers moist, well-drained soil. This holly has dense, prickly leaves so it does well keeping people out of your yard in addition to buffering sound. The flowers have a sweet scent and are a favorite of honey bees.

Dahoon Holly
Dahoon holly foliage and berries. Photo Credit: University of Florida/IFAS

Dahoon Holly (Ilex cassine)

Dahoon holly is native to North America, is tolerant of wet, shady sites (but can also handle full sun), and displays some salt tolerance. This evergreen, small tree is somewhat shrubby. It can grow to be 25 to 30 feet in height with an 8 to 12 foot spread. Dahoon holly has nice light green leaves that are smooth, not prickly like ‘Emily Bruner’ holly. It has a moderate growth rate.

cultivar magnolia
Bracken’s Brown Beauty as an accent tree in a lawn area. Photo Credit: Beth Bolles, University of Florida/IFAS Extension – Escambia County

Southern Magnolia (Magnolia grandiflora)

It’s hard to beat a majestic southern magnolia in the landscape. Why not utilize it as a screen tree? Now, not all southern magnolias are made equal. There are a few cultivars that do well as screens as well as on their own. ‘Bracken’s Brown Beauty’, ‘Claudia Wannamaker’, and ‘D.D. Blanchard’ are three that come to mind and are readily available in the trade. Southern magnolias can reach up to 80 feet tall and 20 to 40 feet wide depending on cultivar and growing conditions. Not only do these three cultivars have beautiful dark green, leathery leaves, their leaves also have brown undersides. These versatile trees can tolerate are variety of soil conditions and they are very wind resistant. And as another bonus, they have beautiful, fragrant flowers.

Eastern Redcedar
Middle-aged Juniperus virginiana ‘Burkii’: Burk Eastern Redcedar. Photo Credit: Ed Gilman, University of Florida/IFAS

Eastern redcedar (Juniperus virginiana)

If your looking for softer texture in your landscape, then you can’t go wrong with a cedar tree. Unbeknownst to its name, eastern redcedar can be found growing all over the United States. This evergreen conifer prefers well-drained sites in full sun. It can grow 30 to 40 feet in height by 10 to 20 feet wide. Eastern redcedars have good salt tolerance. These trees produce beautiful, blue-green foliage. One key to growing this tree successfully is to give it space. Plant trees 12 to 24 feet apart. If using as a screen, you may consider staggering this tree to give it the space it needs.

There are lots of good options when selecting trees for a screen. It’s important you select plants that fit the site. The University of Florida has an excellent plant selection tool found at the Florida Trees for Urban and Suburban Sites webpage.