by Carrie Stevenson | Apr 8, 2020
A biologist at Blackwater State Forest monitors endangered woodpecker habitat in a longleaf pine. Photo credit: Carrie Stevenson, UF IFAS Extension
In the Southeastern United States, our forests were once primarily longleaf pine-dominated ecoystems. Frequent summer thunderstorms and their accompanying lightning strikes would routinely set a portion of the forest afire. With plenty of space to move, wild animals relocated to safer portions of the forest or hunkered down in deep, winding gopher tortoise burrows underground. The longleaf pine’s life cycle has co-evolved with fire in such a way that its young growth stage is resistant to fire, and its success as a species requires fire to open up the canopy.
As human populations grew larger in the South, much of that forest land was harvested for timber, pitch, and turpentine, then cleared for agriculture and urban development. The American Southeast now has only 5% of that original longleaf pine forest. Thankfully, continued efforts led by organizations like the Longleaf Alliance and The Nature Conservancy have reminded folks of the species’ importance, and led to conservation and restoration efforts.
University of Florida Extension Agent surveys a planted forest with a producer in Washington County. UF/IFAS Photo: Josh Wickham.
Now, we have a newer mix of forest cover, with specimen trees preserved in parks and yards. In addition, we also have sustainable tree farms. You may have passed a wooded area where you noticed pine trees (mostly loblolly and slash in the south) were in perfect rows—these are being farmed, planted in rows just like any other crops. While they will be harvested eventually, during their lifetimes these trees fulfill all the roles we appreciate in wild forests–animal habitat, oxygen production, carbon dioxide uptake, and cooling via transpiration. The other positive of sustainable forestry is that almost as soon as they’re cut, they’re replaced. Trees are grown in a stepwise fashion to ensure there is always an available harvest. Multiple generations are grown at once to ensure there is rarely a truly bare spot in the landscape.
With 17 million acres in production, forestry makes up the largest agricultural commodity in Florida. When managing, planting, and harvesting trees, modern foresters take tree physiology, invasive species, disease outbreaks, and genetics into serious consideration. These professionals help produce necessary items for life; wood for construction, furniture, books, and the all-important toilet paper, which has emerged as a bartering item in the time of COVID-19. For more information on forestry in Florida, visit the University of Florida’s School of Forest Resources and Conservation.
by Carrie Stevenson | Feb 18, 2020
Several Extension offices in the Panhandle are collecting air potato bulbils for National Invasive Species Week. Photo credit: Esther Mudge, Escambia County
The non-native invasive air potato vine (Discorea bulbifera) has wound its way throughout Florida, from pine forests and creek floodplains to backyards. Their heart-shaped leaves are most noticeable in the spring and fall, where they can take over large areas, not unlike their fellow invasive vine, kudzu. In the fall, the plant produces a potato-like tuber called a bulbil, which grows above ground on the vine. The bulbils drop in the winter and then produce new vines the following spring.
The vine’s growth has been uncontrolled or kept back by herbicide for years, until researchers discovered a biological control insect known as the air potato leaf beetle (Liloceris cheni). In the vine’s native Nepal and China, the beetle controls growth by surviving on the leaves of the air potato, its sole food source. After extensive study, the USDA approved the use of these beetles in Florida to control the air potato vine population here. UF IFAS Extension offices statewide have participated in these beetle release programs, providing thousands of beetles to homeowners and property owners seeking to manage the invasive vine using a chemical-free technique. Left alone, air potato vines can smother full-sized trees, blocking the sunlight and causing them to collapse under the weight of the intertwined vines.
From 2012-2015, beetles were able to reduce air potato vine coverage and bulbil density by 25-70% (depending on location and density of beetle population). The active beetle-production phase of a UF IFAS grant has ended, but researchers are committed to the goal of reducing this nuisance species statewide.
To assist with this process, several Extension offices in the Panhandle are sponsoring a bulbil collection during National Invasive Species Week (NISAW, February 23-29). This effort will serve two important roles: to remove bulbils from the natural environment and to provide a seed source for university researchers seeking to grow air potato vine in a controlled environment, sustaining a continued population of air potato beetles for distribution.
For more information on Air Potato Vines and Leaf Beetles, visit https://bcrcl.ifas.ufl.edu/airpotatobiologicalcontrol.shtml or contact your local County Extension office.
by Carrie Stevenson | Jan 22, 2020
Master Gardeners demonstrate correct tree planting techniques.
Last week, we celebrated Florida’s Arbor Day. “What?” you may say—“Isn’t Arbor Day in the spring?” Well, yes and no. National Arbor Day is celebrated in the spring (April 24 this year), usually within a day or two of Earth Day. However, because of the wide range of climatic environments throughout the United States, each state has its own date based on ideal growing conditions. As it stands, Florida’s is the 3rd Friday in January, as we are situated so very far south. Alabama and Georgia, where so many of us north Floridians experience similar weather, hold their Arbor Days in late February.
Contrary to popular opinion, the optimal planting time for trees is not in the spring, but in fall and winter. Planting during dormancy allows trees to focus their energy resources on growing healthy roots. In the coming spring, a steady supply of warmth, sunshine, and pollinators will bring on leaf growth, flowers, and fruit.
Check with your local Extension offices, garden clubs, and municipalities to find out if there is an Arbor Day event near you! Several local agencies have joined forces to organize tree giveaway events and sales in observance of Florida’s Arbor Day.
Saturday, January 25th
Leon County: UF/IFAS Extension Leon County Master Gardeners will assist with the county’s Arbor Day tree planting at 9 a.m. Martha Wellman Park, 5317 W. Tennessee St., Tallahassee.
by Carrie Stevenson | Nov 7, 2019
A female striped lynx spider protects her egg sac. Photo credit: Carrie Stevenson, UF IFAS Extension
With Halloween just behind us, some of us may still have fake spiders in our yards and cotton webbing all over the shrubbery. Spiders (along with bats) are among those creatures feared and demonized in folklore this time of year. It is important to remember, however, that both organisms are important predators and managers of our insect population.
Last week during a walk on the Extension property, I came across a large brown spider hovering protectively near her egg sac. Perched in a newly planted pine tree, I saw no obvious web. Instead, the spider loosely wrapped the pine’s needles with silk, forming a support structure for the relatively large egg sac.
Newly hatched striped lynx spiderlings on silk scaffolding covering a plant. Photograph by Laurel Lietzenmayer, University of Florida.
On further research, I learned that this female striped lynx spider (Oxyopes salticus) would have mated just once, after responding to a male’s courtship display (involving drumming and elaborate leg touches). She would have produced the egg sac 1-4 weeks after mating, attaching it to the pine needles, and will tend to it until her young emerge 20 days later. Up to five days after hatching, lynx spiderlings disperse by “ballooning” from the plant—they release a silk thread into the air, allowing the wind to carry them off like a tiny skydiver. Those spiderlings will mature into adults by 9 months, living their entire lifespan in just one year.
During that year, though, lynx spiders are important predators of pest insects. Instead of catching bugs in a web, they stalk their prey like a big cat—hence the name, “lynx.” They prey on many fly species, but also on bollworms and green stinkbugs that are major pests of cotton and soybean crops. These spiders are beneficial and highly vulnerable to insecticides.
by Carrie Stevenson | Aug 1, 2019
Reddish, round spots are the first sign of Entomosporium Leaf Spot on Indian Hawthorn. Photo credit: Beth Bolles, UF IFAS Extension
Indian hawthorn (Rhaphiolepis spp.) is one of those great evergreen shrubs with such a reputation for hardiness that most folks tend to plant it and not worry about it. Indian hawthorn is not a Florida native, but is adapted to our weather conditions and is widely used in home landscapes throughout the Southeast.
However, it is important that homeowners and landscape managers pay attention to them, particularly during the warm, often wet weather growing season. During such conditions, the plant is vulnerable to Indian hawthorn leaf spot, caused by a fungus called Entomosporium mespili. Several years back, this fungus spread through the once-popular red-tip plant (Photinia fraser), to the extent that this species is now rarely used.
An Indian hawthorn plant heavily affected with leaf spot fungus can be covered with round circles on the green leaves, eventually leading to plant death. Photo credit: Carrie Stevenson, UF IFAS Extension
Symptoms of leaf spot fungi include small, circular red spots on young leaves, which then expand into larger patches. On older leaves, the spots are gray in the middle with red/maroon borders. Eventually, leaves can drop and entire plants may defoliate and die. The disease typically spreads through rainwater or overhead irrigation.
To manage the disease, it is best to create space between a sick plant and a healthy one to allow better air circulation. This will allow leaves to dry off after rainfall events and prevent expansion of spores. Be sure not to overwater, prune, or fertilize shrubs that show signs of the disease, as this encourages growth—the fungus thrives particularly well on young, vigorously growing leaves.
For leaf spot problems that become difficult to manage with just cultural practices, fungicides containing chlorothalonil, myclobutanil, or propiconazole may be used. Always follow label instructions when using chemical management and apply in the spring or fall. In addition, dead or dying plants should be removed and replaced with cultivars showing resistance to Entomosporium leaf spot, including Eleanor Tabor, Indian Princess, Gulf Green, Betsy, Blueberry Muffin, Georgia Petite, Olivia, and Snow White.
