During a recent hike through wooded property in Walton County, our Florida Master Naturalist class came across a stunning example of an American Beech tree (Fagus grandifolia). As we looked closely at its thick, sinewy trunk (often compared to an elephant’s skin), the bark changed hues from a deep red to silvery gray and brown. A hardwood, it has been used over the years to make furniture, railroad ties, and beer barrels. Like many of the local hardwood species, beech wood holds up to decay when exposed to water and early settlers used it to build mills and water wheels.
The colorful, smooth bark of a beech tree is eye-catching and strong. Photo credit: Carrie Stevenson
During the growing season, the beech tree can be identified by its distinctive dark green, tooth-edged leaves. Beeches are deciduous but have the unique quality of usually keeping dead leaves on their branches all winter, which also helps with identification in the forest.
The most fascinating observation, to me, was the series of tightly swirled branch buds ready to sprout at the tips of each new branch. So pointed that they’re easily confused as thorns, these long protrusions will eventually grow into new branches.
These four buds formed as an “emergency” response to the branch being cut and will eventually replace it. Photo credit: Carrie Stevenson
At the end of one branch that had been cut, the tree’s internal “emergency response” system formed four new immature branches, which had the intimidating appearance of a claw. Eventually, one of these buds will outcompete the others and grow into a new branch.
Beeches are of course known for the beech nut, eaten by humans and wildlife alike. If you’re considering a beech for a home landscape, be sure you have a wide open space with moist soil, as a mature beech can grow up to 75 feet high and 40-60 feet wide. Its low branches create a lot of shade, so understory plants are usually unnecessary or even impossible to grow.
Dr. Ramon Leon, Extension Weed Specialist, West Florida Research and Education Center
Herbicides simplify weed management by allowing you to cover extensive areas in a relatively short time, and reduce the need for time-consuming control practices such as hand weeding. Additionally, many herbicides have the advantage of selective control. Selective herbicides are those that kill weeds without significantly injuring the desired plant. In turfgrass, selective herbicides are particularly important because we do not have the option of using cultivation or non-selective herbicides, as is commonly done in other agricultural systems such as row crops and orchards.
A common misconception is that when a herbicide is registered for use on a given turfgrass species, this herbicide has little negative effect on the turf. In reality, even when the herbicide is registered for a specific turfgrass species, it can cause a certain level of injury. If the herbicide is applied at the recommended label rate, and the growing conditions are ideal, the turfgrass will only suffer minor, temporary injury that may go completely unnoticed. Conversely, the weeds that are susceptible to the herbicide will be severely affected resulting in the desired control.
Over the last few summers, there has been an increase in complaints about herbicide injury on sod farms, golf courses, and home lawns after applications of herbicides, especially during the summer months. Many of those complaints originated from situations in which the application was done properly, using the recommended label rate, and thus the level of injury observed was not justified. After studying all these cases, it was determined that at the time of herbicide application the turf was under a moderate level of stress, but not high enough stress to cause visible symptoms. However, when the herbicide was applied the combined effect of the existing stress, and the stress caused by the herbicide made it harder for the turf to maintain the desired quality. For example, Figure 1 below shows that the turf looked fine before the application (A), but after the herbicide was applied, there was a significant loss in turf cover and quality (B). The interesting aspect is that the injury was not present across the entire treated area, but only on patches (C). Those patches corresponded with sand pockets where soil moisture, especially on hot days, was considerably lower than the rest of the area. In that particular case, the irrigation system was providing enough water to help the turf tolerate the moderate stress of high temperatures and limited moisture, but not enough for the turf tolerate the combined stress that occurred after the herbicide was applied.
Figure 1. Centipedegrass growing during the summer in Florida before herbicide application (A), 3 weeks after herbicide (sulfentrazone and metsulfuron-methyl) application (B). Herbicide injury pattern with highlighted areas showing where sand pockets caused drought and heat stress that contributed to herbicide injury (C).
In Florida, there are a combination of environmental factors such as high temperatures and sandy soils that can create stressful conditions limiting turfgrass growth, especially when irrigation is not sufficient to keep the turf hydrated. Furthermore, we also experience periods of excess rainfall, and areas of turf growing under shade. Additionally, pest problems that affect roots and leaves are frequently found in our state. All these conditions affect turfgrass health and its ability to tolerate herbicide applications. For these reasons, turf producers and managers need to be proactive to help turfgrass overcome the injury that herbicides might cause. To achieve this goal, you need to follow five simple steps:
1) Identify weed problems early. Most weed problems will start in the spring for summer weeds and in the fall for winter weeds. Controlling them when they are small not only increases the effectiveness of our applications, but also allows us to implement our control when the turfgrass is less likely to be stressed.
If herbicide applications are needed when conditions might be stressful for the turf (high temperatures and/or dry conditions)
2) Make sure irrigation is adequate (increase frequency or duration if needed) for up to three weeks following application.
3) Reduce mowing frequency and increase mowing height 0.5 inches for up to 3 weeks following a herbicide application, to allow the turfgrass to continue producing energy to support its recovery. Mowing too short and too frequently immediately after the application weakens the turfgrass.
4) Fertilize with a small amount of nitrogen (0.25 to 0.5 lb N/acre) a week or two after herbicide application to help the turf recover and produce new leaves.
5) If the turfgrass is suffering from serious pest problems (pathogens, nematodes or insect infestations) do not apply herbicides on the affected areas until the turfgrass has recovered.
Maintaining optimal turfgrass growth is the best way to ensure that herbicide applications will maximize weed control while still protecting the health and aesthetics of your turfgrass.
For more information on growing turfgrass in Florida, please see the following:
Saltbush seed in “bloom” stands out in a salt marsh dominated by black needlerush. Photo credit: Zach Schang, FDEP
In the spring and summer, no one notices the little green shrub hidden among wax myrtle and marsh elder at the edge of the salt marsh. However, if I’m leading a group of students or a Master Naturalist class through the same area in the fall, it’s the first plant people ask about. The saltbush or groundsel tree (Baccharis halmifolia) blooms dramatically in late September and October, with feathery, dandelion-like white “flowers” on female plants. These seeds are dispersed far and wide by the wind. Male plants typically grow side-by-side with females, and produce yellowish, tubular blooms at the same time. Characterized as both a large shrub and a small tree, the saltbush typically branches from multiple trunks and ranges in height from 2-10 feet. The leaves are rough to the touch and slightly succulent, enabling the plant to hold onto moisture in the sandy, hot environments on the uphill edges of wetlands in which it thrives.
The leaf of Baccharis angustifolia is narrower than B. halmifolia. Both are succulent, enabling the plants to hold on to moisture in a salty environment. Photo courtesy Shirley Denton, Florida Plant Atlas.
The leaf of Baccharis halmifolia is lobed and wider than B. angustifolia is narrower. Both are succulent, enabling the plants to hold on to moisture in a salty environment. Photo courtesy Forestry Images.
The plant is often confused with its near relative, false willow (Baccharis angustifolia), which is typically co-located with saltbush in coastal wetlands. It also blooms white in the fall, but can be differentiated by its slender, almost needle-like (but also succulent) leaves.
Saltbush is not typically used in the home landscape, as some people are allergic and the seeds are poisonous if ingested. Properly planted, however, it is a perfect addition to a butterfly garden because the male plants’ fall flowers provide nectar to numerous butterfly species, including the monarch. Another ideal location for saltbush would be a rain garden or the edges of a stormwater pond. Coastal property owners on the bay or Gulf would find it an excellent addition due to its tolerance of the year-round salt spray. The species is very hardy–tolerant of both wet and dry soils–along with a variety of soil pH levels. Plant saltbush in full sun with at least 3-5 feet between young plants.
For additional information on the characteristics of saltbush, please see the UF publication, Baccharis halmifolia Saltbush, Groundsel Bush and check out this entertaining video from our Lee County colleague, Stephen Brown, as he immerses himself in a stand of saltbush.
Summer is full of simple pleasures—afternoon rainstorms, living in flip flops, and cooling off in a backyard pool. Among these, one of my favorites is walking out my door and picking handfuls of figs right from the tree. Before we planted our tree, my only prior experience with the fruit was a Fig Newton—I’d never eaten an actual fig, much less one picked fresh. Now, they are my favorite fruit.
When ripe, figs are a deep shade of pink to purple. Larger green figs will ripen over the course of a few days. Photo credit: Carrie Stevenson
Native to Asia Minor and the Mediterranean, figs were introduced to Florida in the 1500’s by Spanish explorers. Spanish missionaries introduced these relatives of the mulberry to California a couple hundred years later. Figs are best suited to dry, Mediterranean-type climates, but do quite well in the southeast. Due to our humidity, southern-growing figs are typically fleshier and can split when heavy rains come through. The biggest threats to the health of the trees are insects, disease (also due to our more humid climate) and root-knot nematodes.
Fig trees can grow quite large and produce hundreds of fruit each year. Photo credit: Carrie Stevenson
Our tree started out just a couple of feet tall, but 12 years ago we replanted it along a fence in our back yard. It has grown so large (easily 25 feet tall and equally wide) that it hangs over our driveway, making it handy to grab a few as I hop in the car to run errands. The tree is in full sun at the bottom of a slope, and seems to be a satisfied recipient of all the runoff from our backyard. This position has resulted in a thick layer of soil and mulch in which it thrives.
We usually see small green fruit start to appear in early May, becoming fat and ripe by the second half of June. The tree produces steadily through early August, when the tree’s leaves turn crispy from the summer heat and there’s no more fruit to bear. The common fig doesn’t require a pollinator, so only one tree is necessary for production. The fiber-rich fig is also full of calcium, potassium, and vitamins A, E, and K. As it turns out, the “fruit” is actually a hollow peduncle (stem) that grows fleshy, forming a structure called a synconium. The synconium is full of unfertilized ovaries, making a fig a container that holds both tiny flowers and fruit in one.
The insides of a fig show the small flowering structures that form the larger fruit. Photo credit: Carrie Stevenson
With the hundreds of figs we’ve picked, my family has made fig preserves, fig ice cream, baked figs and of course eaten them raw. We typically beg friends and neighbors to come help themselves—and bring a ladder—because we can’t keep up with the productivity. Often you can tell you’re near our tree from around the block, as the aroma of fermenting fruit baking on the driveway is far-reaching.
No matter what you do with them, I encourage planting these trees in your own yard to take full advantage of their sweet, healthy fruit and sprawling shade. As Bill Finch of the Mobile (AL) botanical gardens has written, “fresh…figs are fully enjoyed only by the family that grows them, and the very best figs are inevitably consumed by the person who picks them.”
As a University of Florida/IFAS Weed Specialist, I have been receiving multiple phone calls and e-mails from homeowners, homeowner associations (HOA), lawn care companies and contractors, municipalities, and county managers requesting a list of herbicides that are “safer” than glyphosate. When I ask them the reason for this particular preference, all of them acknowledged that their concern originated from hearing about the IARC report.
The first point that I always explain to people concerned about this issue is that most of the scientific evidence indicates that glyphosate does not have a higher carcinogenic risk compared to many other substances that they are normally exposed to in their daily activities. The second point is that it is important to continuously monitor how chemicals we use affect our health and the environment in the long run. The IARC report is a reminder that we should keep a close eye on glyphosate, the most widely used herbicide in the world, but it is not necessarily a call to stop using it, because at this point there is no direct evidence that it causes cancer in humans.
Very frequently, regardless of the technical details, many homeowners and citizens in urban areas are considering not using glyphosate in their gardens and landscapes, and they would like to use “safer” herbicides.
What do you mean by “safer?”
If you mean lower risk as a carcinogen, then most herbicides registered for use in urban areas would be acceptable because none of them are considered “probably carcinogenic” by IARC or any other regulatory agency. Therefore, you have multiple options to choose from. However, many of the conversations have lead to the statement, “No, I want something that is less toxic than glyphosate!”
Toxicity in pesticides is predominantly assessed using the lethal dose 50 (LD50), which indicates the amount of a chemical that kills 50% of a reference population of test animals (e.g. mice, rabbits, rats). When the LD50 is high, this means that the chemical has low toxicity, and when the LD50 is low it is considered that toxicity is higher because small amounts of the chemical can cause mortality. Glyphosate has one of the highest LD50s for herbicides. In other words, glyphosate is one of the least toxic herbicides available based on the LD50 standard. Therefore, if we want an alternative herbicide that is less toxic, we do not have any options for urban areas.
What about organic herbicides?
Many people associate “organic” with “safer.” This can be misleading because it depends on how safety is measured. For example, there are multiple organic herbicides that are considered to have the same or even higher toxicity when compared with glyphosate, because many of them have irritant and corrosive properties. Furthermore, organic herbicides have dramatically different herbicidal properties that make them unlikely alternatives to effectively replace glyphosate.
Glyphosate has one of the broadest spectrums of control, so it kills many different weed species effectively. Also, glyphosate works systemically. This means that it is absorbed by leaves and then moves inside the plant to growing points, roots, and other propagating structures. This systemic effect increases the ability to kill relatively large plants. In contrast, the majority of organic herbicides have a contact effect, so they only kill the tissue they touch without being able to move inside the plant. Therefore, they are effective at killing very small plants (<2 inches tall). Large plants can suffer leaf burning after treatment with organic herbicides, and if the application is done properly, the user will see a lot of control shortly after the application (Fig. 1). However, the plants will soon recover and the control level will decrease because, unlike plants treated with systemic herbicides, they can produce new growth from tissues that were not directly expose to the herbicide.
Figure 1. White clover (4 inches tall) control after treatment with glyphosate and twelve different organic herbicides based on natural oil extracts from plants. The green bars represent the level of control 7 days after treatment (DAT) and the yellow bars indicate control 21 DAT.
Considering the lack of alternatives to replace glyphosate, if you want to stop using this herbicide, and you do not want to use any other synthetic herbicides, because their toxicity might be higher, then you need to recognize that weed management will be more challenging. It is unfair to ask lawn care companies or members of HOAs to stop using the tools they have to control weeds and yet expect “weed free” lawns, gardens, and landscapes. Controlling weeds in these scenarios without glyphosate and other synthetic herbicides will require more intensive use of mechanical control approaches and hand weeding. Also, if relying on organic herbicides, these herbicides will have to be frequently applied (probably once or twice a week) in order to kill the weeds at the right time (before they get too big). Also, all these activities will increase weed control costs and the results will likely be not as satisfactory. Thus, you might end up paying more to have lawns and landscapes that will have more weeds escaping control. If this is not acceptable to you, then you probably should be more open to consider the weed control tools we have available. Also, you should be more vigilant about what are the appropriate ways to use them to minimize their risks to humans and the environment, while obtaining the benefits that you are seeking. Otherwise, you should get used to seeing more weeds in the landscape, and to be fair… this might not be as bad as some people think.
