by Mark Tancig | Aug 28, 2025
A healthy coneflower in Leon County’s Demonstration Garden. Credit: Jessica Thrasher
My last Gardening in the Panhandle article was about the many diagnostic services provided by UF/IFAS Extension. In this article, I get to share the results of those services concerning samples recently submitted to the North Florida Education and Research Center (NFREC) Plant Disease Diagnostic Clinic (PDC).
Anthracnose in Dogwood (Cornus florida)
Before you get too concerned, this is not the dogwood anthracnose (Discula destructiva) that many of us have heard about from friends and colleagues up north, but one of the more common anthracnose species (Colletotrichum gleosporoides) that infects a variety of fruits, vegetables, and ornamentals.
Typical leaf symptom of common anthracnose disease on a magnolia. Credit: UF/IFAS.
This sample came from a homeowner who brought us a branch from a sick looking dogwood. As many of you know, due to a host of issues, from a short lifespan to living in the southern end of its range in a warming climate, dogwoods have been faring pretty bad lately, with most landscape plantings showing signs of decline or death. While Florida extension agents are informed that it is not the terrible anthracnose from up north, some couldn’t help but think the worst. I was delighted to get a good sample for identifying the disease – one that showed both healthy tissue and diseased tissue – and finally confirm what is causing the common decline symptoms seen in Leon County dogwoods. We bagged up the sample and delivered the next day to the NFREC PDC.
Within a week, the results came back and confirmed the run-of-the-mill anthracnose. This Anthracnose, caused by the fungus Colletotrichum gleosporoides, causes lesions (spots) and/or blights (larger areas of the leaf browning) beginning at the leaf margins that tend to expand and end up causing premature leaf drop. Unfortunately, once we see the damage, typically in the summer, it is too late for any remedy, as the infection begins in the spring. In addition to good practices to encourage good airflow – proper spacing, pruning – and minimize moisture on leaves – irrigate the soil, not the leaves, water in the morning – you will also need to be able to handle some amount of damage. Removing fallen leaves and branches is also helpful to reduce the chance of it cycling back the following spring. Chemical control options include 2-3 applications of preventative fungicide sprays containing chlorothalonil, myclobutanil, mancozeb, or thiophanate methyl early in the spring according to label directions.
Aster Yellows in Purple Coneflower (Echinacea purpurea)
The deformed blooms of a coneflower with Aster Yellows. Credit: Jessica Thrasher
I’ve had a few questions about Aster Yellows (Candidatus phytoplasma asteris) over the years but have never positively identified the disease in plant material. So, I was somewhat excited to see some of the purple coneflowers in our demonstration garden showing peculiar symptoms. Actually, I was alerted to the strange looking plants by a Master Gardener Volunteer who had been weeding the area. We delivered a sample to the NFREC PDC and in just over a week had results.
Aster Yellows is a disease caused by a phytoplasma and the sample can only be diagnosed with molecular techniques and genetic sequencing. Phytoplasmas, by the way, are a type of bacteria that lack a cell wall and are transmitted plant to plant via insect vectors, typically leafhoppers. Once inside the plant, these phytoplasma can move with plant sap and begin to disrupt the vascular system, causing malformed and discolored flowers, plant deformations, and stunted growth. While members of the Aster family – daisy, sunflower, goldenrod – are common hosts of the disease, Aster Yellows has been found to infect over 300 species in at least 38 plant families. Other species of phytoplasma, also causes lethal yellowing and lethal bronzing of palms and several witch’s-broom diseases.
Since there are not any chemical treatments for Aster Yellows, prevention is key. Once observed, it’s best to remove the infected plants as soon as possible to prevent spreading to other nearby species. In agricultural settings, the leafhopper spreading the bacteria becomes the main target to control using various insecticides. However, in ornamental settings, simply removing the infected plants is the recommended practice.
Stay Observant
Many common diseases are present in every landscape. By ensuring soil and plant health, many of these diseases can be tolerated with little damage. It is important for gardeners and landscapers to be on the lookout for problems so they can be dealt with before they get out of hand. UF/IFAS Extension provides assistance through our county offices and diagnostic clinics to help confirm identification of the pest and provide science-backed control options. If you think you have an issue in your landscape, please reach out to your local county extension office.
Article co-authored by Fanny Iriarte, Diagnostician with NFREC PDC.
by Joshua Criss | Aug 23, 2025
Identifying the plants present in your gardens and landscapes is a critical skill. These plants are the sculptors of our local environment. As such, it’s important to understand how they affect local ecology, and what services they may provide. Three overarching categories you’ll find as you delve into plant ID are “native”, “introduced”, and “invasive”. The latter of these is the subject of this post. Invasive is often a misunderstood term but hopefully this will clear up some of that misconception.
Definitions
Before any other conversation can even take place, it’s important to define terms. The first, and most important of these is “Invasive”. Believe it or not, there is an official definition laid out by the USDA under Executive Order 13112. It states, “an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.” Alien in this instance being any propagation material of a species not native to a particular ecosystem.
Invasive contrasts with “Native” or “Introduced” species which either naturally occur in an ecosystem or were brought to said system through human activity. Keep in mind that many introduced species have served gardeners very well providing food, beauty, and pollinator support without the risks associated with invasive plants. You can find all these terms defined on the USDA’s website.
Chinese Tallow “Popcorn Tree” Photo: J. LaForest UGA
What’s the Damage
So why is it important to know these species, and more importantly what can gardeners do about them? The primary issue with these plants is how they impact our natural areas. They compete for real estate crowding out more desirable species. They also deprive these species of resources such as sunlight or nutrients often denying nectar to our pollinators.
Not worried about the impact on natural areas? On an economic front, it costs Florida’s taxpayers roughly $179 million per year to manage invasive species, the majority of which is applied to plant species. This number may seem high, but considering a single invasive insect has cost the citrus industry billions in lost production it seems appropriate.
Economics not persuasive? Some invasive plants such as castor bean (Ricinus communis) are very dangerous for humans. Ingestion of this plant carries a high potential of illness and often results in fatality.
Castor Bean Plant
Photo: J. Hollinger
Summing it all up
The bottom line is that invasive plants are not innocuous. The plants we grow in our landscape can and do have detrimental effects on the surrounding environment, the economy, and are potentially deadly to humans. It’s incumbent upon all gardeners to know how to identify these plants. Once you have identified them, it’s important to learn how to eliminate them so they don’t return.
There are many resources out there to help with identification. UF/IFAS has an assessment tool here. This tool allows you to search for individual plants and provides their known status. Another great way to discover the invasive status of your plants, is through the Florida Invasive Species Council or FISC. They are the convergence point between scientists, land managers, and local governments which inform a list of plants with invasive tendencies. That list may be found here.
For more information on controlling invasive species or any other gardening topic, please contact you local UF/IFAS Extension office.
by Donna Arnold | Aug 15, 2025
Kalanchoe Species in Florida: Invasive Threats and Management
Several species of Kalanchoe, widely distributed through horticulture as popular containers and landscape plants, have escaped cultivation and become invasive in Florida. Of the approximately seven species reported outside of cultivation, two have been documented as particularly problematic: Kalanchoe pinnata (commonly known as Cathedral Bells) and Kalanchoe × houghtonii (known as Mother of Millions). Both are listed as Category II invasive plants by the Florida Invasive Species Council (FISC), indicating they have the potential to disrupt native ecosystems. “In Central and South Florida, the plant is listed as invasive; hhowever, there is a cautionary note for North Florida.”
Photo Credit: Donna Arnold, FAMU Extension
Kalanchoe × houghtonii is a hybrid of K. delagoensis and K. daigremontiana, which has led to some confusion in reporting and distribution records. These species belong to the Crassulaceae family and are characterized as succulent herbs with hollow, fleshy stems. K. pinnata features rounded, scalloped leaves, while K. × houghtonii has slender, pointed, fleshy leaves. Their bell-shaped, pendulous flowers range in color from green to red. In Florida, these plants are primarily found in South Florida and along the East Coast, extending as far north as Nassau County.
Photo Credit: Donna Arnold, FAMU Extension
The ecological impacts of Kalanchoe species are significant. Reproduction occurs both sexually and vegetatively, with plantlets forming along leaf margins and even on inflorescences. This species high reproductive rate and ability to thrive in dry, arid environments allow them to invade coastal dune habitats, where they form dense carpets that crowd out native species. Shallow root systems contribute to destabilization of sandy areas by displacing native plants such as sea oats, which are essential for anchoring sand and preserving dune integrity.
Effective management begins with prevention. Homeowners are advised not to plant Kalanchoe species and to avoid dumping landscape material in natural or disturbed areas. Physical control methods include hand-pulling and secure disposal of plant material to prevent regrowth. Chemical control can be achieved using a 5% glyphosate foliar spray, which is effective in killing individual leaves that might otherwise produce new plantlets. Follow-up removal of detached leaves is essential to prevent further spread. Currently, there are no known biological control methods for these species.
For more information and personalized management recommendations, homeowners should consult their local UF/IFAS Extension office. Additional resources are available through the UF/IFAS Center for Aquatic and Invasive Plants, and the Florida Invasive Species Council Plant List.
by Beth Bolles | Aug 9, 2025
You have probably heard about the SoilKit testing option that is available at local UF IFAS Extension offices. Why would you want to use a new testing kit when the traditional soil testing kit is still available ?
UF IFAS Extension SoilKit is an option for those who want their turfgrass test results based on the latest evidence-based science. This is especially important when dealing with the application of phosphorus, a potentially polluting nutrient. If your soil measures adequate phosphorus for our warm season turfgrasses, you don’t want to add more.
UF IFAS Extension SoilKit. Photo by Beth Bolles, UF IFAS Extension Escambia County.
The good news is that UF IFAS turfgrass research has established thresholds for when nutrients like phosphorus are needed. SoilKit is aligned with these thresholds and will only recommend nutrients based on the evidence-based science.
SoilKit does cost more than the traditional soil testing. The convenience is that it includes postage so you put it directly in your mailbox for pickup. Another positive is that when you register your kit online, you can locate your home on a map and mark the square footage of the lawn area. When you get your results in a few days, there is no guess work. You will get a list of products and amounts to purchase for your size lawn.
SoilKit can be used to test other plant groups including gardens and shrubs. If you have questions about using SoilKit, your local Extension office can help.
by Donna Arnold | Jul 6, 2025
Zinnia Woes: What’s Causing Terminal Shoot Curling?
On a quiet stroll to the greenhouse early Monday morning, something unusual caught my eye—our zinnia plants looked noticeably different. Their vibrant green shoots had begun to curl at the tips, a subtle but clear sign that all was not well. Do not be alarmed if your zinnias are showing similar symptoms—it is a common issue. Curling at the terminal shoots is often a plant’s way of signaling stress. Whether it is due to environmental factors, pest activity, or nutrient imbalance, these twisted tips are clues worth investigating. Understanding the “why” behind the curl is the first step toward helping your zinnias return to their radiant, blooming selves
Common Culprits Behind Curling Zinnias
Environmental Stress: Zinnias are sun-lovers, but extreme heat, strong winds, or sudden temperature swings can cause their terminal shoot to curl as a defense mechanism.
Watering Woes: Both overwatering and underwatering can lead to leaf curls. Too much water suffocates roots, while too little causes drought stress—either way, the plant reacts by curling its leaves.
Pests: Aphids, thrips, and spider mites are notorious for feeding on tender new growth. Their sap-sucking habits distort leaves and can transmit viruses.
Diseases: Fungal infections like powdery mildew or bacterial leaf spot can cause curling, especially when combined with poor air circulation.
Nutrient Deficiencies: A lack of nitrogen, magnesium, or manganese can lead to curling and yellowing of new growth. Soil testing can help pinpoint the issue.
What You Can Do:
- Ensure consistent watering—moist but not soggy soil is ideal.
- Inspect regularly for pests and treat with neem oil or insecticidal soap.
- Improve air circulation by spacing plants properly and pruning overcrowded areas.
- Feed with a balanced fertilizer and consider a soil test if symptoms persist.
- Remove and destroy severely affected plants to protect the rest of your garden.
Healthy zinnias reward you with bold, cheerful blooms. A little detective work now can keep your garden dazzling all season long. For more information on Zinnias, contact your local Extension office or follow the links below.
https://gardeningsolutions.ifas.ufl.edu/plants/ornamentals/zinnia/
https://edis.ifas.ufl.edu/publication/FP623
https://nwdistrict.ifas.ufl.edu/hort/category/annuals-2/page/2/#:~:text=When%20planting%20zinnias%2C%20it’s%20recommended,than%20the%20foliage%20whenever%20possible.
by Beth Bolles | Jun 20, 2025
Shade is a wonderful feature in the landscape as we move into our summer months. It can also offer an opportunity to include a different palette of beautiful plants the bring color and brighteness to some filtered shade or full shade locations.
Here are a few plants to consider for those low light areas of the yard.
The native oakleaf hydrangea, Hydrangea quercifolia will do well in dappled shade spots. The leaves are attractive on their own but the addition of large flowers make it very showy. This native hydrangea will like a little moisture but soils should be well drained. A little morning sun is fine but afternoon shade is very helpful as the summer months progress.
The old standard Japanese aucuba, Acuba japonica, is a favorite with it’s green leaves speckled with yellow. New growth is damaged by sun so this evergreen shrub is best with a good amount of shade. Be sure to place in a spot with good air circulation to make the environment less conducive to some plant pests.
Each Aucuba leaf has a unique pattern. Photo by Beth Bolles, UF IFAS Extension Escambia County.
One of the shrimp plants that really needs shade is the White shrimp plant, Justicia betonica. Although this can be damaged in freezing weather, it is worth replanting every spring in a small grouping. Plants are easily started from cuttings and sometimes they will return from roots in the protected shade areas.
White bracts with pink flowers of White shrimp plant. Photo by Beth Bolles, UF IFAS Extension Escambia County.
An annual that is very showy for shade is related to the shrimp plant. Persian shield, Strobilanthes dyerianus is grown for it’s iridescent purple and silver foliage. It thrives in our heat with a little water when rainfall is lacking. It grows well either planted in the ground or in a container to provide bright color amongst the green foliage plants of your shady spot.
A bit of dappled morning sunlight on the Persian shield leaves. Photo by Beth Bolles, UF IFAS Extension Escambia County.
Most people know the Cast iron plant, Aspidistra elatior, which is a full shade plant. Plants that receive too much sunlight with have scalding spots. Although green foliage is attractive in summer, consider one of the cultivars with various types of variegation. You may choose a selection with white or yellow stripes through leaves or a plant with lots of white spots throughout green leaves.
