by Julie McConnell | Oct 23, 2017
Cypress twig galls on bald cypress leaves. Photo: J_McConnell, UF/IFAS
Bald cypress Taxodium distichum is a native tree that is commonly planted in landscapes because it is adaptable to many sites and grows quickly. It is an interesting tree because it has soft flat leaves that fall off in the winter like other deciduous shade trees; however, it belongs to the Cypress family which consists mostly of needled evergreens.
Like the other cypresses, bald cypress produces cones in the fall, which is a primary means of reproduction for the species in natural settings. During the same season that cones are maturing, you might also see what looks like cones forming at the tips of branches among the leaflets rather than along the stem. These mysterious growths are not cones but rather twig galls.
Bald cypress twig galls are abnormal growths of leaf bud tissue triggered by the attack of the cypress twig gall midge Taxodiomyia cupressiananassa. In late spring, adult midges lay eggs on new leaves of the bald cypress. As the eggs hatch and midge larvae start feeding on the bald cypress leaves the growth of a twig gall is induced. The larvae take advantage of this gall using it for food and shelter throughout the larval stage and into the pupal stage. After pupation, adults emerge from the galls, mate, and females lay an average of 120 eggs over a two-day lifespan as an adult. This first generation lays eggs on mature leaves which starts the cycle again. The galls formed by the second generation of the year fall off and overwinter on the ground.
The galls do not appear to affect the health of trees overall, although the weight of heavily infested branches may cause drooping. There are many natural enemies of the twig cypress gall midge, so applying insecticides are not recommended since they may cause harm to non-target insects. The simplest management option is to collect and destroy the galls in the spring and fall to reduce populations the following season.
To read more about bald cypress trees or the twig gall please see the following publications:
by Beth Bolles | Oct 23, 2017
Trees are a landscape asset for many homeowners. When a new tree is installed in our landscapes, we can’t wait for it to mature to provide shade or landscape interest. The heartbreak for many homeowners comes when this important part of their landscape, begins to decline five to ten years after establishment. We often consider a pest as the cause. The common culprit is often hidden below the mulch and soil and is easily preventable.
When larger specimen trees are installed in residential and commercial landscapes, they may be delivered with materials that help hold the rootball in place. Strapping often runs over the rootball and when trees are young is several inches away from the trunk. Installers or homeowners often do not cut the strapping during installation.
As this tree continue to grow, the rootball straps will interfere with normal trunk development. Cutting the straps takes only a few seconds at the time of planting. Photo by Beth Bolles, UF / IFAS Extension Escambia County
Over the years, tree trunks will grow in diameter and eventually reach the strapping. Because the strapping is still firmly in place, it can cut into a growing tree, resulting in girdling. Although many trees try to overcome the injured area by forming new wood over and around the girdling, this is a major stress that interferes with water and food movement in the plant. What we see is a tree that may be slower to leaf out in the spring, a thinning canopy, and twig dieback. These symptoms may be confused with another cause since the strapping is normally hidden from view.
The crape myrtle on the right has a very thin canopy. Investigation found a severe area of girdling from strapping left uncut at planting. Photo by Beth Bolles, UF / IFAS Extension Escambia County.
If you do have a tree that exhibits the above listed symptoms, it never hurts to look at the trunk and root flare just below the mulch and soil surface. If you find strapping still in place, cut it so that it is loose. Depending on the severity of the problem, this may not save the tree but it is worth a try on your important investment.
by Mark Tancig | Sep 18, 2017
Hopefully, by this time of year, most north Florida gardeners have harvested their figs and are enjoying fig preserves or fig bars. But if you’ve noticed your fig leaves dropping a little early, it may be a sign of the fungal disease Fig Rust (Cerotelium fici).
Figs are a great fruit tree for the north Florida home garden. Not only do they provide a tasty reward (if you can keep the birds and squirrels away), but they are fairly easy to maintain and are bothered by relatively few pests and diseases. One of the few diseases that can be common, however, is fig rust, especially when conditions are favorable. In the case of fig rust, a fungus, warm humid weather is what it likes and well, we have plenty of that.
Figs are a great fruit tree for North Florida. Credit: Mary Derrick, UF/IFAS.
The first signs of the fig rust disease are small yellow to yellow-green spots/lesions on the upper surface of the leaf that turn a reddish-brown color as they get larger. A heavy infestation causes the leaves to turn yellow and drop early. While fig rust does not injure the fruit, repeat occurrences of premature leaf drop can adversely affect the overall health of the tree, resulting in yield loss. Another concern is that if the leaves drop too early, the tree will flush out with new growth heading into winter. This new growth can be injured by early freezes and cause a loss of fruit the following season.
Fig rust on leaves. Credit: UF/IFAS.
What can you do to prevent and/or cure fig rust? Unfortunately, once you see the yellowish-green/reddish-brown spots on the leaves, it’s too late to provide any control. As always, proper cultural practices can help. Pruning the tree to provide adequate airflow keeps the leaves as dry as possible during our humid summers. Remember to prune fig trees in Florida after fruit harvest, not in the dormant season, since fruit is borne on previous year’s growth. Another cultural control to prevent fig rust is to rake diseased leaves out from under the tree. The fungal spores in the fallen leaf litter pass the disease on to next year’s leaves. Other cultural controls include providing adequate moisture and placing a healthy dose of mulch around the tree. Figs require minimal fertilizer. Using a general complete fertilizer with micronutrients (such as a 10-10-10), young trees should receive 1 cup (1/2 pound) and mature trees 4-8 cups (2-4 pounds) per year.
There are currently no chemical controls approved for fig rust in Florida. The classic Bordeaux mix is recommended by various authors to be used as a preventative fungicide during the dormant season, before the lesions appear on the leaves. The Bordeaux mixture is a mix of copper sulfate, lime, and water in a 1:1:10 ratio and is considered an organic pesticide. This mix has been used since the late 19th century and was discovered by accident after botanists and farmers realized that grapevines sprayed with the mix to deter theft had less fungal problems. As with any pesticide, be cautious when using. Overuse of copper-based fungicides can cause copper to build up in soils, leading to potential issues to plant and human health.
While figs are generally worry free for our area, fig rust is one disease to be on the lookout for. Good gardening practices can reduce the occurrence of this disease and ensure a bountiful harvest. For questions on growing figs or about the fig rust disease, visit the UF/IFAS EDIS website – edis.ifas.ufl.edu – or contact your local Extension office.
by Carrie Stevenson | Sep 8, 2017
Trees are often among the first victims of hurricane-force winds. Photo credit: Mary Duryea, University of Florida.
Well, it is the peak of hurricane season (June 1-November 30), and this one is proving to be no joke. After having all summer to heat up, Gulf and Atlantic water temperatures peak in late August-mid September, feeding storms’ strength. Legendary hurricanes like Harvey, Katrina, and Andrew all made landfall during this time of year. The models for Irma show likely impacts in Florida, and due to its extreme size, most of the state is in line to endure heavy rain and wind regardless of location.
From a landscaping perspective, hurricanes can be truly disastrous. I will never forget returning home after evacuating from Hurricane Ivan and realizing all the leaves had been blown from nearly every tree in town. Mid-September suddenly looked like the dead of winter. A Category 3 storm when it landed near the southwest corner of Escambia County, Ivan was responsible for a 40% loss of tree canopy in our county.
Even if the Panhandle is not directly impacted by a storm, it is always smart to prepare. Research conducted by University of Florida arborists and horticultural specialists have yielded some practical suggestions.
To evaluate trees for potential hazards;
- Know your tree species and whether they are prone to decay or wind damage (more below).
- Look for root or branch rot—usually indicated by very dark spots on the bark.
- Tree structure—is there a single, dominant central trunk? Are branches attached to the trunk in a U-shape (strong) or V-shape (weak)?
- Smart pruning—never “top” (cut the tops from trees) but instead prune crowded limbs and remove limbs that are dead, dying, or hanging above power lines.
As for species selection, keep in mind that pines generally do not perform well in gale-force winds. Longleaf pines are quite strong, but common slash pines often snap or lean in storms. Even if a pine tree survives, it can be vulnerable to damage or death from pine bark beetles. It is wise to monitor pines for up to 2 years after a storm.
In addition, a survey conducted throughout the southeastern United States after hurricanes from 1992-2005 yielded important information on the most (and least) wind-resistant tree species. Live oaks and Southern magnolias topped the list, while pecans and cherry laurels performed poorly. This full, user-friendly report from the study is a useful tool.
For more hurricane preparedness information, visit the UF IFAS Extension Disaster Manual online or contact your local Extension office or Emergency Management agency.
by Beth Bolles | Sep 8, 2017
Trees are a valuable resource. They add beauty to our community, serve as food and shelter for animals, filter the air, and cool urban environments. Trees can also be a liability when poorly maintained, damaged, or diseased. There are often times when an arborist is needed to help determine the best course of action for the tree.
There are many individuals who are involved in the tree care and removal business. Not all of these people are certified in the care of trees. Arborists are people who receiving training in the planting, care, and maintenance of trees.
Professional arborists have specialized training to create safe, structurally sound trees, even when damaged by storms. Photo by Beth Bolles, UF IFAS Extension Escambia County
Certified arborists go through a voluntary certification process with the International Society of Arboriculture which means that they have at least three years experience and have passed a comprehensive examination developed by tree experts. A certified arborist maintains certification by attending regular training courses.
An arborist may also be a member of another organization which helps professionals stay up-to-date on tree care techniques and information. These include the National Arborist Association and the American Society of Consulting Arborists.
Hiring an arborist to work on your trees is important for several reasons. An arborist can evaluate the tree and determine the steps necessary to create a healthy specimen. In regards to pruning, the professional will determine what type of pruning is necessary and remove branches properly.
Professionals will also perform tree care practices that are recommended by University research. A few practices that the arborist would not perform include topping trees, using climbing spikes on trees which are not being removed, and making flush cuts against the trunk.
Flush cuts are damaging to trees and can create a future hazard in your landscape. Photo by Beth Bolles, UF IFAS Extension Escambia County
Finally arborists have the skills and equipment to safely and efficiently prune or remove trees. This includes personal and property damage insurance and workers compensation insurance.
Next time you need tree work or advice, hire a professional for the job. It will definitely be worth the investment.
by Sheila Dunning | May 25, 2017
As oak trees are now fully leafing out and people start hanging out in the shade of the canopy, many of you are noticing strange growths on the branches. They look like potatoes, spiky cones and fuzz balls on the leaves and stems. Don’t worry. It’s just a harmless wasp that chose that tree to create a nursery for her young.
Galls are abnormal plant growth or swellings comprised of plant tissue. Galls are usually found on foliage or twigs. These unusual deformities are caused by plant growth-regulating chemicals produced by tiny wasps. The chemicals produced by these insects interfere with normal plant cell growth.
The life cycles of the various gall-forming wasps are highly variable. Two or more years are required for gall wasps that develop in woody twig galls to reach maturity. Gall-forming wasps usually overwinter as adults in protected places away from the host tree. As the buds break in the spring and the leaves begin to expand, these small wasps start to lay their eggs in expanding plant tissue. During the egg-laying process or early larval-feeding period, specialized body glands secrete growth-regulating chemicals that interact with certain plant chemicals to produce these abnormal growths.
After a brief period of cell growth, gall development stops completely. Once these galls are formed, they do not continue to use nutrients from the host plant. The insect is confined within “its house” and feeds only on gall tissue during the remainder of its development. The galls provide shelter, protection, and food for the immature wasps. Inside a gall, the larvae are surrounded by tissues rich in nutrients
There are a variety of gall-forming species of small wasps that commonly infest oak, Quercus spp ., trees. Galls generally are aesthetically objectionable to homeowners who find them unattractive and fear that galls will cause damage to the health of their oak trees. Most leaf galls on oak cause little or no harm to the health of a tree. However, twig or branch galls may cause injury by distorting branch development in a heavily infested tree.
Chemical control is seldom suggested for management of leaf galls on oak. Cultural methods of control may be effective in reducing the impact of these insects. Some fallen leaves may harbor various life stages of gall-producing pests. Therefore, it may be useful to collect and destroy all infested leaves. Some of these pests overwinter in twigs and branches of oak. Where such woody galls are detected, prune and destroy the infested plant material when the galls are small and have just started to develop. But, remember every bug needs a home!
All photos by Eileen Buss, UF Entomologist
