Being a gardener in Florida is exciting. We have many plants to choose from and the weather is mostly pleasant but always seeming to surprise us. One disadvantage of living in such a place, in addition to having so many growing zones, landscape nurseries, and major shipping ports, is that invasive species that land in Florida don’t like to leave. One newcomer in the lineup of invasive pests is the crape myrtle bark scale (Acanthococcuslagerstroemiae). This invasive insect pest made its way from Texas and, as of a few weeks ago, the only Florida sighting had been in Santa Rosa County. Unfortunately, this pest has now been confirmed in Leon County. Landscapers and gardeners in north Florida should learn how to identify this pest and what options are available for control.
The crape myrtle bark scale, as the name suggests, has a pretty specific host – the crape myrtle (Lagerstroemia spp.). However, in the United States, this scale has also been found feeding on our native beautyberry (Callicarpa americana). Due to the widespread planting of crape myrtles, these should be the gardeners primary focus when looking for this new pest. If present on the tree, it is hard to miss. These scales feed on the bark and are a snow-white color. Being a scale, they produce honeydew that is then covered in black sooty mold. So, if you see a crape myrtle with black branches, look closely and you may see the white scales. If you crush these scales and they leave a pink goo on your fingers, then you very likely have crape myrtle bark scale. Of course, you can send a picture or sample to your local county extension office for confirmation.
Black sooty mold and white scales along the trunk and branches are a tell-tale sign of crape myrtle bark scale. Credit: Mark Tancig, UF/IFAS.
If you do happen to find crape myrtle bark scale in your own landscape, or one that you manage, proper control is important to prevent it from moving along any further. Since scales suck on sap and are protected by an outer shell, systemic insecticides are the preferred product for effective control. These include the neonicotinoids, such as imidacloprid (Merit) and dinotefuran (Safari). The larval stage can be controlled with a horticultural oil, sometimes mixed with another insecticide like bifenthrin (Talstar), however, this will not control the adults. Another option is to completely remove the tree and burn all of the plant material.
Excessive sooty mold has turned these branches black. Be on the lookout for crape myrtles looking like this to help identify crape myrtle bark scale. Credit: Jim Robbins, Univ. of Ark. CES. Retrieved from bugwood.
The crape myrtle bark scale can significantly reduce the aesthetic value of crape myrtles due to the black sooty mold that covers the bark. It is also known to reduce flowering and can lead to thinning of leaves. Since crape myrtles make up a big part of our managed landscapes, let’s all work together to scout for this pest and control it when found. If you have questions, please contact your local county extension office.
Difference in flowering due to crape myrtle bark scale damage. Credit: Jim Robbins, Univ. of Ark. CES. Retrieved from bugwood.
The Florida Forest Service implements the tree champion program in Florida. Credit: Florida Forest Service.
Humans love to measure and rank things. Whether it’s the tallest, the widest, or the most of something, we want to know about it, rank it, and, of course, brag about it if it’s ours. The biggest pumpkin, cheeseburger, truck tires, and so on. Gardeners and plant people are no exception. Actually, when you combine the pride of something you’ve grown with some type of measurement or rank of grandeur, it drives even more competition. Hence, fairs! So, it’s no surprise that there is an official rank of largest tree for each state. These large specimens are known as “Champion Trees” and every landowner I know of would love to have one on their property.
The idea of recognizing Champion Trees goes back nearly a century when the American Forestry Association, now known simply as American Forests, launched a campaign to engage the public in forestry activities. To tap into our desire to rank things and compete, the campaign encouraged a competition to find the largest specimens of selected trees. American Forests still maintains a registry of the national Champion Trees and their current goal of the program is to help people identify tree biodiversity and foster a desire to preserve and protect trees.
The Senator – no longer with us – was the state champion cypress. Credit: Creative Commons.
In Florida, the Division of Forestry (DOF), part of the Florida Department of Agriculture and Consumer Services (FDACS), maintains a statewide registry of these Champion Trees. According to FDACS’s Florida Champion Trees website, the largest native tree in the state is a bald cypress (Taxodium distichum) with a trunk measuring 537 inches in circumference (nearly 15 feet wide), stands 101 feet tall, and has a crown spread of 49 feet. That’s a big ol’ cypress tree! Just in case you were wondering, the smallest Champion Tree is a corkwood (Leitneria floridana) with a trunk measuring nine inches in circumference (almost three feet in diameter), 17 feet tall, and a crown spread of eight feet. That is a big ol’ corkwood!
Corkwood (Leitneria floridana), a native wetland tree, is the smallest state champion. Credit: Creative Commons.
Now comes the exciting part. The Florida Champion Trees website (https://www.fdacs.gov/Forest-Wildfire/Our-Forests/Florida-Champion-Trees) has the entire list of trees for you to peruse and includes a list of trees that are yet to have a champion specimen designated. There is a nomination form that, when submitted, will prompt a visit by a County Forester with DOF who will confirm the tree’s measurements. If all checks out, your tree could be a champion!
Math isn’t always fun! Here is Euclid explaining math in Raphael’s The School of Athens. Credit: Creative Commons.
There are a lot of things gardeners need to know to cultivate a beautiful landscape. Between plant zones, scientific names, soil chemistry, and pest identification, being a gardener takes curiosity and willingness to learn new things. Unfortunately, one topic that needs to be well understood, especially when it comes to applying pesticides and fertilizers, is a subject that many cringe when they hear it – mathematics!
Some of the most common mathematical concepts to have a good grasp on for gardening include area, converting decimals to percentages and vice versa, estimating volume and converting units, and determining how much fertilizer to be applied based on your fertilizer grade.
Here’s a couple tips to help you gardeners out with math.
Area
Most often, we need to know the square footage of our gardens. Rectangles are straightforward, you multiply length (in feet) by width (in feet) to get feet squared. Since most yards are not rectangles, we sometimes need to use other shapes to best calculate the area, such as circles and/or triangles. The area (A) of a circle is , where “π” is 3.14 and “r” is the radius (half of the diameter or the distance from the center to the edge). Remember that the little raised 2 means you multiply the radius by itself twice, not by two.
Most of the time, square feet is the best area unit to use. But just in case you need to know, one acre equals 43,560 square feet. So, if you find your lawn is 10,000 square feet, that means you have 0.23 of an acre (10,000/43,560).
Get your calculator’s out! Credit: iStockphoto.
Percent Conversions
This one may be better understood by most, but this becomes important later when we determine fertilizer needed or doing volume conversions. Basically, any percent can be divided by 100 to convert it to a decimal that can be used easily in other calculations. For example, 15% is the same as 0.15 (15/100). The easy way to remember is that 100% is the same as one, and 50% is the same as 0.5.
Volume Estimation and Conversions
Determining volume is required when figuring out how much mulch is needed for a garden bed or soil required for a raised bed. Converting one unit to another is especially important when determining how much pesticide product is needed to prepare a mixture.
For mulch and soil, the cubic feet (cf) or cubic yards (cy) are needed to figure out how many bags or truckloads will be needed. Most bulk products are sold by the cubic yard. Since we are dealing with volume, we need three measurements, the length, width, and depth. If we want to add three inches of mulch to a 500 square foot garden, we multiply the 500 by 0.25 feet (3”/12” equals 0.25 inches) to get 125 cubic feet. That is about 62 bags of mulch from the hardware store, which are often sold in 2 cubic foot bags. If we divide 125 cubic feet by 27 (three feet in a yard so 3’ x 3’ x 3’ = 27) we now have the answer in cubic yards and find that we need about 4.5 cubic yards of mulch. One cubic yard is roughly a half of a full-size pickup truck bed.
When it comes to converting liquid volume units to help with pesticide mixtures, fortunately we have the internet to help. However, it is a good idea to at least be familiar with converting ounces to gallons and vice versa. Since 128 ounces equals 1 gallon, to go from gallons to ounces you multiply by 128. For example, 0.5 gallons equals 64 ounces (0.5 x 128). To go from ounces to gallons, we just divide by 128. For example, 192 ounces equals 1.5 gallons (192/128).
Applying the proper amount of fertilizer keeps your landscape healthier and protects local waterbodies. Credit: UF/IFAS.
Calculating Fertilizer Needed
Okay, bear with me, as we are about to do some hard math and piece together several of the above concepts. First of all, most fertilizer rates are provided by extension resources and given in terms of pounds of a particular nutrient for a set area, usually 1,000 square feet. For example, when using slow-release fertilizer a homeowner should apply no more than one pound of nitrogen for every 1,000 square feet of lawn. To figure out how much actual fertilizer to apply to meet the recommendation, we will need 1) the recommended rate, 2) the size of the lawn, and 3) the fertilizer grade on the product (the three numbers that represent the percent N, P, and K). Our rate is one pound nitrogen per 1,000 square feet. The size of our lawn is 50 feet by 30 feet, so 1,500 square feet. We are going to use a 16-0-8 fertilizer. Now, here is the hard part! To figure out how much of our 16% nitrogen fertilizer will provide one pound of nitrogen, we need to convert 16% to a decimal (16/100 = 0.16) and then divide the amount of fertilizer we need by that number – 1 pound/0.16 – to find that 6.25 pounds of our fertilizer product are required for each 1,000 square feet. Since we have 1,500 square feet, we need to multiply our answer by 1.5, which gives us a total of 9.4 pounds.
Math is hard and there are usually many methods to get the same solution. When using pesticides and fertilizers in the home landscape, it’s important to make sure we’re using the right amount of materials to minimize the chance of harming ourself, our plants, and the local environment. If you need help, or would like someone to check your work, contact your local extension office.
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.
Gardeners delight in finding a versatile and resilient landscape plant, especially one that is easily shared. Unfortunately, when a plant checks off those characteristics, it usually finds itself on the invasive species list (see IFAS Assessment). Well, in the case of yarrow (Achillea millefolium), we get a tough plant that is easily propagated, has attractive blooms and foliage, attracts butterflies, and is considered native! As I’ll discuss below, it doesn’t come totally flawless.
Yarrow, in the Asteraceae family, is a great addition to the landscape.
Yarrow is considered a cosmopolitan species. It is found across the entire northern hemisphere and there has been a lot of mixing of native and introduced plants, causing much confusion amongst botanists. It is currently considered a single, though complicated, species. Much of the mixing is due to its history with man, being carried along all sorts of expeditions, even the mythical character Achilles, where the plants genus name comes from. The species name comes from the finely divided leaves – like a thousand leaves. It is in the daisy and sunflower family, called the Asteraceae, or composite family, due to the flower heads being composed of many individual flowers.
The cluster of flowers over the feathery leaved foliage is what makes yarrow stand out. The classic yarrow is white-flowered, but breeders have developed many cultivars in an array of colors, including red (‘Rosea’ or ‘Paprika’), pink (‘Cerise Queen’), purple (‘New Vintage Rose’), and yellow (‘Gold’ or ‘Lemon’). Yarrow is also great for its drought tolerance and has few pests or diseases that bother it. It is even reported to be deer resistant! It can be propagated by seed and is easily divided.
Yarrow ‘Paprika’ is a commonly found yarrow cultivar. Source: Timeh87, Creative Commons license.
The common yarrow shows off beautiful white blooms over the feathery foliage. Credit: Rachel Mathes, UF/IFAS.
With all these great attributes comes one potential problem – it is considered toxic to dogs, cats, and horses. Yarrow contains a toxic alkaloid, called achilleine, that can poison some mammals. So, if you have an adventurous pet that likes to chew on random plants, then you may want to skip adding yarrow to your landscape. Achilleine is the same compound that has led it to be used by humans for centuries as a blood clotting agent. Achilles was said to have carried yarrow to the battlefield in Troy for his soldiers and the plant has been known as herba militaris and soldier’s woundwort. Of course, always consult a doctor for medical advice!
