by Mark Tancig | Apr 7, 2022
Despite a sharp increase in costs recently, wood products remain a common landscape and garden material. They can be used for building structures, such as arbors and sheds, or for hardscapes and garden accessories, like raised vegetable garden beds or landscape timbers used for edging. Many homeowners may be confused on the safety of using certain wood products, especially around plants grown for consumption. This article hopes to explain the various options and the known safety concerns.
Raised beds are a common use of treated lumber in the garden. Credit: Molly Jameson/UF IFAS
Gardeners seem to be mostly concerned with the safety of using preserved wood products around food plants. Pressure-treated lumber is usually suggested whenever the material will be exposed to the elements and especially when in contact with the soil. Non-treated lumber, while free of any preservatives, will simply not last as long in the landscape, especially in Florida where we have a long growing season, are wet, and have lots of organisms – termites, fungus, etc. – that love to break down wood. If the wood is in direct contact with the soil, such as in a raised bed garden, you can expect non-treated lumber to last a year, maybe two, compared to three to five years with pressure-treated lumber. Wood products used for structures not in contact with soil can last significantly longer but, even then, non-treated products will need to be protected with sealers or paints to extend their longevity.
To address the safety of pressure-treated wood products, the wood products industry, and the federal government, in 2004, phased out the use of potentially hazardous chemicals used in the process – namely arsenic and chromium. Wood products preserved with these compounds were either chromated copper arsenate (CCA), ammoniacal copper arsenate (ACA), or acid copper chromate (ACC). Since 2004, much of the lumber available at hardware stores is micronized copper azole (CA) or alkaline copper quaternary ammonium (ACQ). The abbreviations for each are usually found on the little label stapled on to the lumber. So, while copper used to prevent fungal damage is still a component of pressure-treated lumber, the arsenic and chromium used to protect the wood from insect damage has been removed. Railroad ties, sometimes still in use and for sale, are much more toxic than even the older pressure-treated products because of the use of creosote and other oil-based compounds to preserve the wood.
Preserved wood products contain the preservation method on the tag stapled to the product. Credit: USDA Forest Products Lab
By removing these potentially hazardous compounds from pressure-treated wood products, gardeners should expect no adverse effects from it’s use. A Human and Ecological Risk Assessment of ACQ treated wood that was done in 2007 found exposure levels well below health benchmarks when directly contacting the wood and even with some ingestion of the material, such as contacting the wood and putting hands directly in mouth.
Even though these hazardous materials have been removed, there are still some precautions you should take when using pressure-treated lumber. These precautions include wearing a mask when cutting the lumber and not burning the lumber. This is to prevent inhalation of the chemically treated sawdust or smoke. It’s also not recommended to compost pressure-treated lumber since the chemicals can affect the microbes in your compost pile.
For those still concerned with the use of pressure-treated wood products around food crops, there are other options. In addition to using non-treated wood products or a plastic liner to separate the pressure-treated lumber from your edible garden plants. There are many other materials that can be used instead. Concrete blocks or other stone materials can be a good option. Logs from cut trees, although will rot like non-treated lumbers, can add a natural type of look to the garden.
Stone, metal, and concrete blocks are good alternatives to lumber. Credit: Mark Tancig/UF IFAS.
For additional information on pressure-treated lumber, visit this Clemson University website – https://hgic.clemson.edu/factsheet/treated-wood-in-the-landscape/. If you have any questions about the use of wood products in the garden or on how to build a raised bed garden, contact your local UF/IFAS Extension office.
by Ray Bodrey | Apr 7, 2022
The thistle has long been an enemy of ranchers, county roadside maintenance crews and homeowners. Often difficult to control, it causes both headaches for producers, in reduction of grazing for livestock as well as being an eyesore for gardening enthusiasts. There are nine different species of thistle in Florida. Most of these are closely related, therefore the control protocols are the same. Only one species is a perennial, and all others are biennial. A biennial plant grows from seed in one year and produces seed for the next.
Thistle that has begun to bolt. Photo Credit: Dr. Jason Ferrell, University of Florida/IFAS Agronomy Department-Weed Science.
It’s important to understand the biology of the thistle in regards of seeking control of this fast spreading weed. This plant will grow a taproot and a cluster of leaves in the first year. This is known as the rosette stage. In the second year, a stalk will appear from the center of the rosette. This is called “bolting”. A seed head will form once the bolting stage is complete. Amazingly, one thistle plant can amass 4,000 seeds. The plant faces its demise after releasing the seeds. The rosette growth stage is mostly during the winter months with bolting occurring from January to July. This is important to note when battling this persistent weed.
As for control, preventing the thistle from producing seed is the most important management measure. Otherwise, little can be done to stop the outbreak of the weed. For homeowners, manually removing the rosette and tap root by hand is effective with small stands. Be careful and wear protective coverings on your hands and arms. Keep in mind, the plant will come back if the tap root is not fully removed.
Other physical control methods, like mowing, have mixed results. This can be effective if mowing occurs after the bolting stage has occurred, but before the seed head forms. However, this is tricky, as thistle plants often do not bloom at the same time.
Thistles in the rosette stage are very susceptible to herbicides. Although, applying a herbicide after the seed head has formed has little effect on control. Herbicides containing 2,4-D are very effective for landscapes. Timing of application is critical. The key to controlling this weed is by scouting and identifying stands as early as possible.
If you’re a beekeeper, there is an upside to this weed. Delicious honey can be made from the thistle bloom.
For more information on thistle, please contact your local county extension office.
Supporting information for this article can be found in the UF/IFAS EDIS Publication, “Thistle Control in Pastures” by Dr. Brent Sellers and Dr. Jason Ferrell.
UF/IFAS Extension is an Equal Opportunity Institution.
by Beth Bolles | Mar 31, 2022
The February Q&A on Growing Tomatoes offered valuable tips for the home gardener to be successful with tomatoes in 2022. Below are the reference materials related to specific questions that were asked.
Let’s start out with the panels favorite tomatoes including hybrids and heirlooms.
Evan: Supersweet 100, Sungold
Larry: Amelia, Brandywine, Cherokee Purple
Sam: Better Boy, Tasti Lee, Sweethearts
Matt: Mountain Magic, Mountain Rouge, Bella Rosa
Daniel: Black cherry and Big Beef
Why are tomatoes red?
Can we grow tomatoes year around?
I have very sandy/loamy soil. Do I have a chance at successfully growing tomatoes?
What is the best time to start tomatoes in North Florida?
If one grows in raised beds, should one rotate where in the bed tomatoes are planted?
If you plant tomatoes in mid-March, how long will they continue to produce fruit?
I’m thinking of trying hydroponic gardening on a few tomato plants this year. Do you think a 50/50 mix of perlite and vermiculite would be a good approach for a soil medium? I’d like to use 5-gallon buckets and keep maintenance to a minimum.
What tomatoes grow best in inland Bay County? Coastal vs inland considerations.
Best type for all day sun (speak to tomatoes light requirements)
What is the best tomato variety for Northwest Florida? I need one go-to variety for both regular tomatoes and cherry type.
How to get more tomatoes, less vine?
My tomatoes get black on the bottom and rot. What causes this and how do I prevent it?
Do tomatoes need a lot of water?
Why do my tomatoes split/burst/crack while on the vine?
Any suggestions for how to handle especially wet years like last summer? My tomatoes really suffered.
How do I keep the leaves from getting dark spots that spread and kills foliage?
How do you string tomatoes vine to a stake?
What causes catfacing?
Every year I’m having trouble with an amazing amount of insect infestations on my tomatoes & peppers I grow in containers. What can I do to help?
How do marigolds (which variety) or basil aid tomatoes?
Please talk about save tomato seeds to grow. Some can’t afford to buy potted tomato plants.
Can you add nutrients into the soil from last year’s tomatoes to reuse again this year?
by Sheila Dunning | Mar 31, 2022
As the temperatures warm into the 70’s and the rain chance remains good, keep an eye open for disease in your lawn. Large patch disease is common in turfgrass this time of the year. It is caused by the fungus Rhizoctonia solani. The fungus is present in the soil and thatch layer year-round. When the temperatures rise into the 60’s and 70’s it begins to spread. Large patch thrives under these conditions, especially when the soil is wet. With frequent showers the disease spreads quickly. The first symptom of large patch is circular, discolored areas within the lawn. The outer borders of the patches are orange to yellowish in color. In the center of the circle there are grass blades trying to green up again. They are usually unsuccessful, resulting in odd-shaped patches of dying grass that begin to connect to each other. A simple field diagnostic techniques to confirm large patch disease is to pull on the diseased grass shoots near the edge of the circle. The blades will come loose from the stolon easily. At the base of the leaves the stem and sheaths will appear dark brown and rotten. Yes, it is large patch. 
If the weather gets colder or hotter very quickly, the disease will go back into dormancy. Looking at the long range temperature predictions, cool night and warm days are likely to continue for awhile. So, start looking for a fungicide or two or contact your pest control service. However, remember fungicides don’t cure existing problems. They are utilized as a protectant for the unaffected portions of the grass. When favorable conditions are present, the turf should be sprayed in order to keep the fungus from penetrating the grass blades. Repeat applications will be needed for as long as the weather is cool and wet. Check the product label for the correct intervals. Several cultural practices promote large patch infection including over-fertilization, over-irrigation, low mowing height, poor drainage and excess thatch. This spring after the grass has greened-up on its own is a good time to look at these factors and make corrections. Keep a close eye because as soon as the temperatures drop again in the fall, large patch can reappear if the corrections were not complete. For more information: https://edis.ifas.ufl.edu/lh044
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.
by Matt Lollar | Mar 31, 2022
Piedmont azalea (Rhododendron canescens) flowers. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County
Native azaleas are stunning this time of year. These deciduous shrubs (and sometimes small trees) often go unnoticed until they bloom in the spring. Three species native to Florida are the piedmont azalea (Rhododendron canescens), the Florida flame azalea (Rhododendron austrinum), and the swamp azalea (Rhododendron viscosum). Piedmont azaleas have whitish to pinkish blooms, Florida flame azaleas have yellow to orange blooms, and the white blooms. All three species have a wonderful honeysuckle-like, sweet fragrance. All three serve as outstanding focal points in the landscape.
Native azaleas and other deciduous azaleas have varying site preferences. Like other azaleas, piedmont and Florida flame azaleas prefer moist, well-drained, acidic soils. However, as the name would suggest, the swamp azalea tolerates wetter locations. All three species prefer partial shade (morning sun and afternoon shade are best) locations and can grow up to 15 feet tall.
Rhododendron x ‘Aromi Sunny-Side-Up’ in bloom. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County
In addition to these beautiful native azaleas, a number of deciduous hybrids have been developed. Aromi hybrids have been bred to tolerate heat and humidity. These azaleas were developed from four native species ()from Gene Aromi in Mobile, AL. He developed more than 100 cultivated varieties (also referred to as cultivars). Popular cultivars in the market include ‘Centerpiece’, ‘Aromi Sunrise’, and ‘Aromi Sunny-Side-Up’.
Deciduous azaleas do not require a lot of fertilizer. A controlled release or slow release, acid forming (specifically formulated for azaleas or blueberries) fertilizer is recommended. A fertilizer nutrient ratio of or close to 2-1-1 (N-P-K) should be selected. Plants should be fertilized in spring or early summer, never in the fall or winter.
More information on azales, native and nonnative, can be found on the UF/IFAS Gardening Solutions website.
