by Sheila Dunning | Sep 30, 2013
Most trees are not well adapted to saturated soil conditions. With nearly daily rainfall this spring and summer, sometimes in record amounts, the ground became inundated with water. When the root environment is dramatically changed by excess moisture, especially during the growing season, a tree’s entire physiology is altered. This condition may result
in the death of the tree.
Water saturated soil reduces the supply of oxygen to tree roots, raises the pH of the soil, and changes the rate of decomposition of organic material; all of which weakens the tree, making it more susceptible to indirect damage from insects and diseases. Additionally, with heavy rainfall there is erosion and sediment movement. Exposed roots or roots covered by excess soil add stress to plants. When the rain finally stops, often the tree’s system has been so compromised that it can’t perform the vital functions necessary to survive – it just dies.
When the ground becomes completely saturated a tree’s metabolic processes begin to change very quickly. Photosynthesis is shut down within five hours; the tree is in starvation mode, living on stored starches, unable to make more food. Water moves into and occupies all available pore spaces that once held oxygen. Any remaining oxygen is utilized within three hours. The lack of oxygen prevents the normal decomposition of organic matter which leads to the production and accumulation of toxic gases such as carbon dioxide, methane, hydrogen sulfide and nitrogen oxide. 
Additionally, within seven days there is a noticeable root growth loss. Roots only develop when soil oxygen levels are at 5% -15%. Over time, the decaying roots are attacked by pathogens. The loss of root mass from decay and fungal attack leave the tree prone to drought damage. After only two weeks of saturated soil conditions the root crown area can have so many problems that decline and even death are imminent.
For plants to function there is a need for nutrient uptake. However, in saturated soil anaerobic organisms, primarily bacteria, replace the aerobic organisms that once existed in the soil. These bacteria convert the nitrogen into forms that are unavailable to plants. Also, manganese, iron and sulfur become limited because the soil pH has increased, making the elements unrecognizable. With little to no functioning root system, the trees in saturated soils do not have the means to uptake nutrients, even if they were available.
When a tree experiences these anaerobic soil conditions it will exhibit symptoms of leaf loss with minimal to no new leaf formation. This usually appears two to eight weeks after the soil dries out again. Many trees will not survive, especially the more juvenile and mature trees. However, well established trees may still decline several years later, if they experience additional stresses such as drought or root disturbance from construction.
There is little that can be done to combat the damage caused by soil saturation. However, it is important to enable the tree to conserve its food supply by resisting pruning and to avoid fertilizing until the following growth season. Removal of mulch will aid in the availability of soil oxygen. Basically it is a “wait and see” process. While water is essential to the survival of trees, it can also be a detriment when it is excessive.
by | Sep 16, 2013
While the recently passed Labor Day is often is touted as the traditional “end of summer,” according to the calendar, fall officially will begin with the fall equinox on Sept. 22nd at 4:44 EDT. In north Florida, however, we know good and well that our summer season extends a good bit longer.
Still, even if it just feels right, there is something going on now. When you walk out in the morning, the air feels just a bit more comfortable. The days are getting shorter, and that is beginning to have an effect. Perhaps it’s just wishful thinking, but if you squint just right, you can ALMOST see the end of our long and brutally hot summer.
The word “fall” commonly conjures up images of harvest, falling leaves, the end of the growing season and the beginning of dormancy leading into winter. For gardeners in North Florida, however, the traditional fall period is not a time of winding things down in the garden or even landscape but of revival and renewed effort. It’s a time when we finally can get back into outside and enjoy ourselves as the debilitating heat of summer starts to lose its grip on the weather.
For the next couple of months we will experience a gradual shift to milder weather. There will be cool spells followed by decidedly hot, summer-like weather, but as we move into late October, cooler weather will begin to dominate the scene. Not until mid-to late November do we generally experience the nippy cold weather and changing leaves that tell us, yes, indeed, fall has finally arrived.
One thing you that you might notice that may surprise you may be an increase of vigor in your warm-season bedding plants in September. Even heat-tolerant flowers do not always look their best in August.
Since shorter days mean fewer hours of intense heat, even though the daytime highs may stay about the same, plants begin to experience less stress. This encourages a “second wind”, if you will, in the flower garden that may last well into October or early November. Given this, consider cutting back some of your summer bedding plants and flowers that have grown tall and leggy over the just passed long growing season. This should be done in by the second or third week in September at the latest – and generally involves cutting plants back about one-third to one-half their height.
While you’re at it, it might be a good idea to impose some order on those overgrown flower beds. In addition to cutting back, groom plantings to remove dead flowers and unattractive foliage.
If plants are leaning or have fallen over onto nearby neighbors, prop them up or stake them so they will stand upright. Just about every year at this time I find the remains of some unfortunate plant that was overwhelmed when larger, more vigorous, nearby plants leaned over it.
In addition, if you haven’t done so already, gently trim your everblooming rose bushes, including such popular groups as Hybrid Teas, Grandifloras, Floribundas, Miniatures, Teas, Polyanthas, Bourbons, Chinas and English roses, to name just a few. This should be a very light trimming, little more than deadheading, since the main pruning of everblooming types is done in mid February. On the other hand, keep in mind that many old-fashioned climbers, ramblers, Lady Banks roses and some bush roses that bloom heavily only in spring to early summer will bloom next year on the growth they made this summer. Those roses should not be cut back at all now.
Even though you can get back into the garden to work, it is still too early to plant hardy trees, shrubs, ground covers and vines in the landscape. Temperatures in the 80s and 90s likely will be common in September, and that is still too stressful for new plantings. Wait at least until the cooler weather of October, since the ideal planting season for hardy trees, shrubs and ground covers really is from November through February. And for those that like to plant pecan trees, these are often done in bare root when the trunk of the tree is about the size of a pencil. These MUST be done when completely dormant or you will not have a successful outcome.
While Fall is for Planting, be sure that you don’t start too early!
Keep in mind that even though they will begin to show up in area nurseries this month, it is also is too early to plant cool-season bedding plants. Even if you have an area where your summer flowers have finished and have been removed, it is still too hot to plant most cool-season bedding plants. Instead mulch the area now and wait until the reliably cooler weather of October or November before you plant your bedding plants.
Spring-flowering bulbs, such as tulips and daffodils, become available this month, but there is absolutely no hurry to plant them. Purchase them if you like while the selection is good, but wait to plant your spring flowering bulbs from mid-October through early December.
Keep in mind that insects and diseases stay active through the fall, so continue to control any pest problems with timely applications of the proper material. In addition, don’t forget, now as always, water well during dry periods, and you should have an excellent crop of flowers in October through November.
I guess if you think about it, it’s best to say that Labor Day really marks that time in north Florida when we can anticipate the soon-to-arrive milder weather and look forward to enjoying the delights of gardening over the next few months. When the fall equinox arrives later this month, don’t get carried away. For us, summer will still be lingering for a little while longer.
by Carrie Stevenson | Sep 2, 2013
One of the natural phenomena I’ve loved watching this rainy summer is the dramatic “life and death” cycle of the resurrection fern (Pleopeltis polypodioides). Found most often along the branches and trunks of stately mature live oaks, this plant turns from a dry, crackly brown to a vibrant green in the span of a day.
Dry, brown resurrection fern on a live oak after a period without rain. Photo credit: Carrie Stevenson
Like Spanish moss this epiphyte, or “air plant”, uses a host plant (live oak, pecan, or sabal palm) as its growing surface. Yet the fern does not damage the tree. Its root system is composed of long, winding rhizomes that tuck into the nooks and crannies of the tree’s bark, collecting rainwater and nutrients from airborne dust and nutrients leaching from the trees themselves.
The fern’s unusual response to dry weather is an adaptation that allows the fronds to curl inward, reducing water loss by decreasing surface area exposed to the elements.
Blades of turf-grass will respond similarly to drought, folding in half after several days with no water. However, the resurrection fern takes drought tolerance to a whole new level, capable of losing up to 97% of its water content without dying. As a comparison, most plants will start to die back at a 10% water loss. Several researchers estimate the fern can live 100 years in its dry state. However, true to its name, the resurrection fern will spring back to life after a rain or an increase in humidity.
The fern that was completely dry one day will turn a vibrant green just after a rainfall. Photo credit: Carrie Stevenson
The resurrection fern has earned its place in history for several other reasons. According to literature from early pioneers and indigenous people, members of the Florida Seminole and Miccosukee tribes used the fern in baths to treat insanity. They also made a root mixture of the resurrection fern and Shoestring fern (Vittaria lineata) to treat chronic health conditions and sick babies.
Because of its unique attributes, resurrection ferns were taken in space along with the shuttle Discovery in 1997 as part of a mission to better understand natural phenomena from the perspective of space.
The thin, elongated rhizomes of the resurrection fern root into the crevices of a live oak’s bark. Photo credit: Carrie Stevenson
The plant is native to the eastern United States west to Texas and throughout the American tropics. A variety of the species is also native to southern Africa. It can be propagated by cutting several inches of the rhizomes and placing them into crevices of another tree, log, or rocky area. Dry fronds will respond to being sprayed with water in under an hour, so it’s also a fun experiment to show kids!
For more on resurrection ferns, check out the UF School of Forest Resources.
by Matthew Orwat | Aug 19, 2013
Florida Pecan Field Day and Florida Pecan Growers’ Association Annual Meeting
Jefferson County Extension Office 2729 West Washington Street
Monticello, Florida 8:30 AM, EDT
Thursday September 5th
Harvest time is coming for Florida pecan growers. Demand is up, irrigation needs are down, and fungus pressure has been a serious problem over the entire Southeast.
Producers will meet in Monticello on Thursday, September 5 for the annual field day and Pecan Growers’ Association meeting. If you’re a pecan grower, or just considering it, the morning’s topics and speakers will be a great opportunity to learn more about the pecan business.
The agenda is below. For more information, contact Jed Dillard at 850-342-0187
or dillardjed@ufl.edu. Please make a lunch reservation by noon Tuesday, September 3.
Agenda-
- 8:30 Registration
- 9:00 Welcome……… Mark Brown, President Florida Pecan Growers Association and Jed Dillard, Jefferson County Extension Agent
- 9:10-9:45 “Florida Water Policy and Its Impending Effects on Pecan Production” ……. Carlos Herd, Director Division of Water Supply, Suwannee River Water Management District
- 9:45-10:15 “Management strategies and tactics for suppression of pecan arthropod pests: chemicals, trap crops and everything in between.”
- Dr. Russ Mizell, University of Florida Entomologist, Quincy
- 10:05-10:35 “Controlling scab and other pecan diseases” Dr. Tim Brenneman University of Georgia Department of Plant Pathology
- 10:35-10:55 Break
- 10:55-11:25 “Tree Spacing, Alternate Tree Pruning and Removal, and Tree Transplanting”. Dr. Lenny Wells, UGA Extension Pecan Specialist, Tifton
- 11:25- Noon “Direct Marketing of Pecans – What do I need to Know?”…………..Elena Toro, Suwannee County Extension Agent
- Noon…………… Sponsored Lunch
- 1PM Annual Meeting Florida Pecan Growers’ Association
- 1:15 Tour (Tentative)
- CEU’s: two half ceu’s for ag row crop, tree nut, private applicator and demonstration categories
by Blake Thaxton | Aug 19, 2013
It is that time of year where mysterious webs have invaded pecan trees throughout the Southeast United States. This is definitely the case in the panhandle of Florida. Many have called into the extension office asking for identification of the web mass in their pecan trees. It is the Fall Webworm that has made a home in the pecan tree this fall.
Photograph by James Castner, University of Florida.
Photograph by Andrei Sourakov, University of Florida.
Fall Webworm
The adult fall webworm is a moth that is bright white in color and may have darker spots on its wings. The larvae of the moth are what lives in the tent web masses. Immediately when the larvae webworm hatches out of the eggs it begins to create its webs around foliage in which it will feed on.
Damage
The damage cause by the feeding of the larvae on the pecan trees is isolated to the leaves and they will not eat the nuts. If Defoliation is severe enough it can reduce the current years crop and the following years crop. Several years of defoliation can lead to death of the tree but this is not likely. Obviously the webs are ugly as well and if the tree is not only a producer of pecans but also functioning as an attractive shade tree in a ornamental since this can be a problem.
Control
In most commercial pecan production settings webworms are not very prevalent because of the spray programs implemented. For residential settings the best solution is to manually prune them out because of the lack of proper spray equipment to cover the entire tree. If the problem is bad enough call your local extension agent to get recommendations on products that could be used.
Sources:
Andrei Sourakov and Thomson Paris (2011, April) Fall webworm,Hyphantria cunea (Drury) (Insecta: Lepidoptera: Arctiidae: Arctiinae). Retrieved from http://edis.ifas.ufl.edu/pdffiles/IN/IN87800.pdf
Michael J. Hall. Fall Webworm. Retrieved from http://www.lsuagcenter.com/NR/rdonlyres/68665E57-A2F4-4030-A4E6-55821DCFBDD6/16783/FallWebworm_sheet_.pdf
by Sheila Dunning | Jul 29, 2013
With hurricane season upon us, evidence of preparation is all around us.
Tree trimmers, contracted by the local electrical utility companies, have been removing trees, branches and other vegetation that is “too close” to power lines. Many homeowners are concerned over the practice.
In order to prevent power outages, the federally approved Vegetation Management Reliability Standard, FAC-033-2, requires utilities to manage vegetation growth along the path of power lines to prevent contact. A minimum clearance of fourteen (14) feet between trees and transmission lines in the right-of-way must be maintained at all times in order to achieve service reliability and public safety.
By Florida Statute 163, an electric utility is granted easement or right-of-way on private property in order to build and maintain electric power lines. Vegetation maintenance allows for the mowing of vegetation within the right-of-way, removal of trees or brush within the right-of-way and selective removal of tree branches that extend within the right-of-way by the electric utility personnel, licensed contractors or International Society of Arboriculture (ISA) Certified Arborists. The choice of how to trim trees and manage vegetation growth near a power line (e.g. pruning, herbicides, or tree removal) is primarily made by the electric utility, subject to state and local requirements and laws, applicable safety codes, and any limitations or obligations specified in right-of-way agreements. An individual may contact the utility company to obtain a copy of the right-of-way agreement for their property.
Sometimes, it appears to some that excessive vegetation has been removed. But, remember the utility companies are required to maintain the appropriate clearance “at all times.” For example, in the summer, power lines sag as they expand from rising air temperatures and heavy use. Also, wind and future growth must be taken into account when determining where to prune. Electric utilities usually prune or remove vegetation to a distance greater than the minimum clearances to account for all these factors.
Tree trimming around power lines may seem like a local issue, but vegetation growth also affects interstate transmission lines. The U.S. Department of Energy estimates that electric utility service interruptions cost businesses and communities tens of billions of dollars annually. Tree contact with transmission lines was the leading cause of the August 2003 blackout that affected 50 million people in the Northeastern United States and Canada. In fact, that particular blackout prompted Congress to pass the Energy Policy Act of 2005, which lead the Federal Energy Regulatory Commission (FERC) to establish the Vegetation Management Reliability Standard.
Should we have a storm that impacts Northwest Florida, remember that the clearing of trees and branches provides faster access for first responders, line repair crews, and other emergency service personnel. So, as you watch the preparation work being done, think about where you will be planting a tree so that it can reach full maturity without threatening power lines, therefore, not requiring “ugly pruning!”
