by Les Harrison | Mar 18, 2018
It is easy to notice the display of bright pink puffs erupting on low-growing trees along roadsides. This attractive plant is the Mimosa tree, Albizia julibrissin.
These once popular small trees are commonly found in the yards of older homes in Florida where the display of prolific blooms starts up as the weather warms.
This species is also classified as invasive native to southwest and eastern China, not Florida. Many Florida residents may not realize this tantalizing beauty is actually an aggressive invader in disguise.
The beautiful mimosa is found throughout the Florida panhandle.
Photo: Les Harrison
It has spread from southern New York west to Missouri south to Texas. It is even considered an invasive species in Japan.
Worse yet, mimosas are guilty of hosting a fungal disease, Fusarian, which will negatively affect many ornamental and garden plants. Some palms as well as a variety of vegetables will succumb to this pathogen.
In natural areas the invader will disrupt not only other plants, but also the birds, mammals, amphibians, and insects which depend on the displaced plants for food, shelter and habitat. Other negative traits include the disruption of water flow and aiding the incidence of wildfires.
In natural areas, mimosas tend to spread into dense clumps blocking the light to native plants which prevents them from growing. They are prominent along the edges of woods and wetland areas where seeds scatter easily and take advantage of sheltered, sunlit spots.
Mimosa tree seeds can stay viable for many years in the soil. These seeds will float without damage to their germination potential until they wash ashore to colonize a new site.
Additionally, Mimosa tree seeds are attractive to wildlife. One tree in a yard can infest many acres with the aid of birds and small mammals.
Cut or wind snapped trees quickly regrow from the stump, making this one invader that is difficult to eradicate.
Fortunately, there are a variety of small trees which can replace the Mimosa tree in home landscapes. Many are attractive, but without the unrelenting need to populate the entire subdivision.
This is a beauty-and-the-beast combo tree with too many problems to compensate for its looks.
by Sheila Dunning | Jan 19, 2018
We plant trees with the intention of them being there long after we are gone. However, many trees and shrubs fail before ever reaching maturity. Often this is due to improper installation and establishment. Research has shown that there are techniques to improve survivability. Before digging the hole:
- Look up. If there is a wire, security light, or building nearby that could interfere with proper development as it grows, plant elsewhere.
- Dig a shallow planting hole as wide as possible. Shallow is better than deep! Many people plant trees too deep. A hole about one-and-one-half the diameter of the width of the root ball is recommended. Wider holes should be used for compacted soil and wet sites. In most instances, the depth of the hole should be LESS than the height of the root ball, especially in compacted or wet soil. If the hole was inadvertently dug too deep, add soil and compact it firmly with your foot. .
- Find the point where the top-most root emerges from the trunk. If this is buried in the root ball then remove enough soil from the top so the point where the top-most root emerges from the trunk is at the surface. Burlap on top of the ball may have to be removed to locate the top root.
- Slide the plant carefully into the planting hole. To avoid damage when setting a large tree in the hole, lift the tree with straps or rope around the root ball, not by the trunk. Special strapping mechanisms need to be constructed to carefully lift trees out of large containers.
- Position the plant where the top-most root emerges from the trunk slightly above the landscape soil surface. It is better to plant a little high than to plant it too deep. Remove most of the soil and roots from on top of the root flare and any growing around the trunk or circling the root ball. Once the root flare is at the appropriate depth, pack soil around the root ball to stabilize it. Soil amendments are usually of no benefit. The soil removed from the hole and from on top of the root ball makes the best backfill unless the soil is terrible or contaminated. Insert a square-tipped balling shovel into the root ball tangent to the trunk to remove the entire outside periphery. This removes all circling and descending roots on the outside edge of the root ball.
- Straighten the plant in the hole. Before you begin backfilling have someone view the plant from two directions perpendicular to each other to confirm that it is straight. Break up compacted soil in a large area around the plant provides the newly emerging roots room to expand into loose soil. This will hasten root growth translating into quicker establishment Fill in with some more backfill soil to secure the plant in the upright position.
- Remove synthetic materials from around trunk and root ball. Synthetic burlap needs to be completely removed from the root ball; treated burlap can be left in place. String, strapping, plastic, and other materials that will not decompose and must be removed from the trunk at planting. Remove the wire above the soil surface from wire baskets before backfilling.
- Apply a 3-inch-layer of mulch. To retain moisture and suppress weeds cover the outer half of the root ball with an organic mulch. Do not cover the stem of the plant or the connecting root flare.
- Water consistently until established. For nursery stock less than 2-inches in caliper, this will require every other day for 2 months, followed by weekly 3-4 months. At each irrigation, apply 2 to 3 gallons of water per inch trunk caliper directly over the root ball. Never add irrigation if the ground is saturated.
by Sheila Dunning | Dec 15, 2017
According to Druid lore, hanging the plant in homes would bring good luck and protection. Holly was considered sacred because it remained green and strong with brightly colored red berries no matter how harsh the winter. Most other plants would wilt and die.
Later, Christians adopted the holly tradition from Druid practices and developed symbolism to reflect Christian beliefs. Today, the red berries are said to represent the blood that Jesus shed on the cross when he was crucified. Additionally, the pointed leaves of the holly symbolize the crown of thorns Jesus wore on his head.
Several hollies are native to Florida. Many more are cultivated varieties commonly used as landscape plants. Hollies (Ilex spp.) are generally low maintenance plants that come in a diversity of sizes, forms and textures, ranging from large trees to dwarf shrubs.
The berries provide a valuable winter food source for migratory birds. However, the berries only form on female plants. Hollies are dioecious plants, meaning male and female flowers are located on separate plants. Both male and female hollies produce small white blooms in the spring. Bees are the primary pollinators, carrying pollen from the male hollies 1.5 to 2 miles, so it is not necessary to have a male plant in the same landscape.
Several male hollies are grown for their compact formal shape and interesting new foliage color. Dwarf Yaupon Hollies (Ilex vomitoria ‘Shillings’ and ‘Bordeaux’) form symmetrical spheres without extensive pruning. ‘Bordeaux’ Yaupon has maroon-colored new growth. Neither cultivar has berries.
Hollies prefer to grow in partial shade but will do well in full sun if provided adequate irrigation. Most species prefer well-drained, slightly acidic soils. However, Dahoon holly (Ilex cassine) and Gallberry (Ilex glabra) naturally occurs in wetland areas and can be planted on wetter sites.
Evergreen trees retain leaves throughout the year and provide wind protection. The choice of one type of holly or another will largely depend on prevailing environmental conditions and windbreak purposes. If, for example, winds associated with storms or natural climatic variability occur in winter, then a larger leaved plant might be required.
The natives are likely to be better adapted to local climate, soil, pest and disease conditions and over a broader range of conditions. Nevertheless, non-natives may be desirable for many attributes such as height, growth rate and texture but should not reproduce and spread beyond the area planted or they may become problematic because of invasiveness.
There is increasing awareness of invasiveness, i.e., the potential for an introduced species to establish itself or become “naturalized” in an ecological community and even become a dominant plant that replaces native species. Tree and shrub species can become invasive if they aggressively proliferate beyond the windbreak. At first glance, Brazilian pepper (Schinus terebinthifolius), a fast-growing, non-native shrub that has a dense crown, might be considered an appropriate red berry producing species. However, it readily spreads seed disbursed by birds and has invaded many natural ecosystems. Therefore, the Florida Department of Environmental Protection has declared it illegal to plant this tree in Florida without a special permit. Consult the Florida Exotic Pest Plant Council’s Web page (www.fleppc.org) for a list of prohibited species in Florida.
For a more comprehensive list of holly varieties and their individual growth habits refer to ENH42 Hollies at a Glance: http://edis.ifas.ufl.edu/mg021
by Erik Lovestrand | Feb 27, 2017
Fruits on HLB infected trees ripen prematurely, are small, and often drop from tree. Photo credit: Erik Lovestrand
If we look at the big picture when it comes to invasive species, some of the smallest organisms on the planet should pop right into focus. A microscopic bacterium named Candidatus Liberibacter asiaticus, the cause of Citrus Greening (HLB), has devastated the citrus industry worldwide. This tiny creature lives and multiplies within the phloem tissue of susceptible plants. From the leaves to the roots, damage is caused by an interruption in the flow of food produced through photosynthesis. Infected trees show a significant reduction in root mass even before the canopy thins dramatically. The leaves eventually exhibit a blotchy, yellow mottle that usually looks different from the more symmetrical chlorotic pattern caused by soil nutrient deficiencies.
HLB, referred to as “Yellow Dragon” in China, causes an asymmetrical pattern of chlorosis in citrus leaves. Photo credit: Erik Lovestrand
One of the primary vectors for the spread of HLB is an insect called the Asian citrus psyllid. These insects feed by sucking juices from the plant tissues and can then transfer bacteria from one tree to another. HLB has been spread through the use of infected bud wood during grafting operations also. One of the challenges with battling this invasive bacterium is that plants don’t generally show noticeable symptoms for perhaps 3 years or even longer. As you would guess, if the psyllids are present they will be spreading the disease during this time. Strategies to combat the impacts of this industry-crippling disease have involved spraying to reduce the psyllid population, actual tree removal and replacement with healthy trees, and cooperative efforts between growers in citrus producing areas. You can imagine that if you were trying to manage this issue and your neighbor grower was not, long-term effectiveness of your efforts would be much diminished. Production costs to fight citrus greening in Florida have increased by 107% over the past 10 years and 20% of the citrus producing land in the state has been abandoned for citrus.
Many scientists and citrus lovers had hopes at one time that our Panhandle location would be protected by our cooler climate but HLB has now been confirmed in more than one location in backyard trees in Franklin County. The presence of an established population of psyllids has yet to be determined, as there is a possibility infected trees were brought in.
Another symptom of citrus greening is small, lopsided fruit that are often bitter. Photo credit: Erik Lovestrand
A team of plant pathologists, entomologists, and horticulturists at the University of Florida’s centers in Quincy and Lake Alfred and extension agents in the panhandle are now considering this new finding of HLB to help devise the most effective management strategies to combat this tiny invader in North Florida. With no silver-bullet-cure in sight, cooperative efforts by those affected are the best management practice for all concerned. Vigilance is also important. If you want to learn more about HLB and other invasive species contact your local UF/IFAS Extension office.
by Sheila Dunning | Jun 3, 2016
According to the Atlas of Florida Vascular Plants, there are more than 4,200 plant species naturally occurring in the state. Nearly 3,000 are considered native. The Florida Native Plant Society (FNPS) defines native plants as “those species occurring within the state boundaries prior to European contact, according to the best available scientific and historical documentation.” In other words, the plants that grew in natural habitats that existed prior to development.
Native plants evolved in their own ecological niches. They are suited to the local climate and can survive without fertilization, irrigation or cold protection. Because a single native plant species usually does not dominate an area, there is biodiversity. Native plants and wildlife evolved together in communities, so they complement each other’s needs. Florida ranks 7th among all 50 states in biodiversity for number of species of vertebrates and plants. Deer browse on native vines like Crossvine (Bignonia capreolata), Trumpet Creeper (Campsis radicans), Yellow Jessamine (Gelsemium sempervirens) and Trumpet Honeysuckle (Lonicera sempervirens). The seeds and berries of Black-eyed Susan (Rudbeckia fulgida), Flowering Dogwood (Cornus florida) and Dahoon holly (Ilex cassine) provide vital food for songbirds, both local and migratory. Saw palmetto (Serenoa repens) provides cover for numerous birds and small mammals, as well as, reptiles.
Non-native plants become “naturalized” if they establish self-sustaining populations. Nearly one-third of the plants currently growing wild in Florida are not native. While these plant species from other parts of the world may provide some of the resources needed by native wildlife, it comes at a cost to the habitat. These exotic plants can become “invasive”, meaning they displace native plants and change the diverse population into a monoculture of one species. Chinese privet (Ligustrum sinense), Popcorn trees (Triadica sebifera) and Cogongrass (Imperata cylindrica) have changed the landscape of Florida over the past decade. While Water hyacinth (Eichhornia crassipes) and Hydrilla (Hydrilla verticillata) have changed water flow in many rivers and lakes. These invasive species cost millions of taxpayer dollars to control.
By choosing to use native plants and removing non-native invasive plants, individuals can reduce the disruptions to natural areas. For more information one specific native plants that benefit wildlife go to: http://edis.ifas.ufl.edu/uw384
It learn which plants are invasive go to: http://www.fleppc.org/list/2015FLEPPCLIST-LARGEFORMAT-FINAL.pdf
by Sheila Dunning | Jan 23, 2016
The best time to plant a tree is twenty years ago. The second best time is for Arbor Day. Florida recognizes the event on the third Friday in January, but planting any time before spring will establish a tree quickly.
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.
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 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 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 some day 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
