Air potato leaf beetle. Photo credit: Les Harrison, UF/IFAS.
A small, but brightly colored beetle has appeared in north Florida: the air potato leaf beetle (Liliocetis cheni), a native of East Asia. The beetle, less than half an inch long, has a candy apple red body that stands out against green leaves and the more muted earth tones of most other bugs. The striking bright glossy red coating would be the envy of any sports car owner or fire truck driver.
Unlike other arrivals to the U.S., this insect was deliberately released in 2012 for biological control of air potato. After years of testing, approval was finally given to release air potato leaf beetles to begin their foraging campaign against this invasive plant species. The beetle has very specific dietary requirements and only can complete its life cycle on air potato. The larvae and adults of this species consume the leaf tissue and occasionally feed on the tubers.
When a population of air potato leaf beetles finish off an air potato thicket, they go in search of nourishment from the next patch of air potato. They are sometimes seen during stopovers while in search of their next meal.
Air potato (Dioscorea bulbifera) is an herbaceous perennial vine which is easily capable of exceeding 60 feet in length. It quickly will climb over any plant, tree or structure unfortunate enough to be in its vicinity. The vine also produces copious quantities of potato-like tubers suspended from its vines. Unless collected and destroyed, most of the easily camouflaged potatoes will germinate and intensify the infestation.
Air potato. UF/IFAS Photo: Thomas Wright.
Air potato came to Florida in 1905 from China and quickly escaped into the wild. By the 1980’s it was a serious pest species in south and central Florida, but has gradually become established in the panhandle, too. Chemical control of the air potato has been difficult. Repeated herbicide treatments are required to kill a thicket with multiple plants.
Unlike the air potato leaf beetle that only eats air potato, kudzu bugs eat their namesake vine (kudzu), but also feed on a number of other plants including a wide selection of valuable legumes and be quite destructive. Kudzu bugs were accidently introduced in north Georgia in 2009 and have spread across the south in the ensuing years and become established in north Florida.
It is a pleasant surprise to know air potato leaf beetles are working to limit the invasive air potato vine, but it is sad to think there is plenty more for them to eat.
To learn more about the air potato and the beetle:
Natural Area Weeds: Air Potato (Dioscorea bulbifera)
Air Potato Leaf Beetle Publication
Being a gardener in the panhandle has its advantages. We’re able to grow a tremendous variety of vegetables on a year-round basis. However, in this climate, plant diseases, insects and weeds can often thrive. Usually, chemical measures are applied to thwart these pests. Some panhandle gardeners are now searching for techniques regarding a more natural form of gardening, known as organic. With fall garden planting just ahead, this may be an option for conventional vegetable gardeners looking for a challenge.
Vegetable Garden at UF/IFAS Extension Wakulla County. Photo credit: Ray Bodrey UF/IFAS.
So, what is organic gardening? Well, that really depends on who you ask. A broad definition is gardening without the use of synthesized fertilizers and industrial pesticides. Fair warning, “organic” does not translate into easier physical gardening methods. Laborious weeding and amending of soil are big parts of this gardening philosophy. This begs the question, why give up these proven industrial nutrient and pest control practices? Answer: organic gardening enthusiasts are extremely health conscious with the belief that vigorous outdoor activity coupled with food free of industrial chemicals will lead to better nutrition and health.
As stated earlier, the main difference between conventional and organic gardening is the methods used in fertilization and pest control. In either gardening style, be sure to select a garden plot with well-drained soil, as this is key for any vegetable crop. Soil preparation is the most important step in the process. To have a successful organic operation, the garden will require abundant quantities of organic material, usually in the form of animal manures and compost or mixed organic fertilizer. These materials will ensure water and nutrient holding capacity. Organic matter also supports microbiological activity in the soil. This contributes additional nutrients for plant uptake. Organic fertilizers and conditioners work very slowly. The vegetable garden soil will need to be mixed and prepped at least three weeks ahead of planting.
Effective organic pest management begins with observing the correct planting times, selection of the proper plant variety and water scheduling. Selecting vegetable varieties with pest resistant characteristics should be considered. Crop rotation is also a must. Members of the same crop family should not be planted repeatedly in the same organic garden soil. Over watering can be an issue. Avoid soils from becoming too wet and water only during daylight hours.
For weed management, using hand tools to physically removing weeds is the only control method. As for insect management, planting native plants in the immediate landscape of the organic garden will help draw in beneficial insects that will feast on garden insect pests. The use of horticultural oil or neem oil is useful. However, please read the product label. Some brands of oils are not necessarily “organic”. Nematodes, which are microscopic worms that attack plant roots, are less likely an issue in organic gardens. High levels of organic matter in soil causes an inhospitable environment for nematodes. Organic disease management unfortunately offers little to no controls. Sanitation, planting resistant varieties and crop rotation are the only defense mechanisms. Sanitation refers to avoiding the introduction of potential diseased transplants. Disinfecting gardens tools will also help. Hydrogen peroxide, chlorine and household bleach are disinfecting chemicals allowed in organic gardening settings as these chemicals are used in organic production systems for sanitation. Staking and mulching are also ways to keep plants from diseases by avoiding contact with each other and the soil.
Organic gardening can be a challenge to manage, but better health and nutrition could be the reward. Please take the article recommendations into consideration when deciding on whether to plant an organic garden. For more information, contact your local county extension office.
Supporting information for this article can be found in the UF/IFAS EDIS publication, Organic Vegetable Gardening in Florida, by Danielle D. Treadwell, Sydney Park Brown, James Stephens, and Susan Webb.
Skunkvine illustration. UF/IFAS Center for Aquatic and Invasive Plants.
North Florida gardeners have many non-native, invasive plants to deal with, but none quite as stinky as skunkvine (Paederia foetida). As the name implies, skunkvine has a noticeable smell, especially when the leaves are crushed, and it is an aggressive-growing vine, capable of smothering desirable landscape plants. Gardeners should learn to recognize and control this plant before it gets a foothold in the garden.
Skunkvine is native to eastern and southern Asia and a member of the coffee family (Rubiaceae). It was introduced to Florida prior to 1897 as a potential fiber crop, but quickly spread and is now considered a Category I invasive plant by the Florida Exotic Pest Plant Council (FLEPPC) and as a noxious weed by the Florida Department of Agriculture and Consumer Sciences (FDACS).
Skunkvine can be identified by the following characteristics:
- Aggressive twining vine
- Leaves are opposite each other
- There is a thin flap of tissue on the stem between the leaves
- Leaves have a strong skunk-like odor when crushed
- Clusters of small, tubular, lilac-colored flowers appear in late summer to fall
- Fruits are shiny brown and can persist through winter
Skunkvine flowering. Photo by Ken Ferrin, UF/IFAS Center for Aquatic and Invasive Plants. Used with permission.
Once you have identified skunkvine in your garden, the next step is to work to remove it. For small patches, pulling by hand can be effective but will require monitoring to ensure it doesn’t resprout. When hand pulling, you want to be sure to get as much of the root as possible. For larger areas, chemical control using herbicide products that contain triclopyr, imazapic, or aminopyralid are most effective. Carefully reading the product label will help determine which product to purchase.
Since skunkvine can be easily spread by seed and fragments of stem, care must be taken when disposing of it. The best solution is to place plant debris into a trash bag and dispose of it with your regular household garbage.
By knowing how to identify and manage skunkvine, north Florida gardeners can keep it from stinking up their own gardens, their neighbor’s gardens, and surrounding natural areas that support our native wildlife.
Langeland, K. A., Stocker, R. K., and Brazis, D. M. 2013. Natural Area Weeds: Skunkvine (Paederia foetida). Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. EDIS document SS-AGR-80.
With all the media discussion of “bad” insects, like mosquitoes, many of the good guys are forgotten. One that has been very active this summer is the blue mud dauber, Chalybion californicum. These wasps are metallic blue, blue-green or blackish in color with very short narrow waists. During the summer, female blue mud daubers build nests by bringing water to abandoned mud nests made by other species of mud dauber wasps. They form new mud chambers, stock them with paralyzed spiders and a single egg, then seal the chambers with more mud. Their offspring stay in the chamber, feeding on the spiders, and then pupate in a thin silk cocoon. They spend the winter in the nest, emerging the following spring as adults.
Blue mud daubers are solitary wasps and not known to be aggressive. When the females have carried water to an old black and yellow mud dauber’s nest, she softens it and remolds it to her needs. The result is a very lumpy version of the originally smooth nest. Next she must fill the nest with food for her future offspring. The blue mud dauber prays on spiders.
If orb weavers, lynx or crab spiders are plentiful, the blue mud dauber is able to land on their web without getting entangled and pluck the web to simulate an insect in distress. When the spider rushes to capture its prey, the poor arachnid becomes the victim of the wasp’s paralyzing sting and is quickly flown to the mud nest. However, the preferred host of the blue mud dauber is the southern black widow. Even without the elaborate web game, this wasp can control a dangerous nuisance. Once at the nest with her spider victim, the blue mud dauber stores the paralyzed arachnid at the bottom of a mud cell and lays a single egg onto its body. When the wasp larva hatches it consumes the remaining body of the spider. With a full belly, the mature larva spins a papery silken cocoon within the mud nest and begins to pupate. The following spring an adult wasp chews a round hole in the end of the mud cell and exits it’s winter home.
As adults, the blue mud dauber feeds on nectar from flowers and honeydew secreted by insects. Should you encounter a large congregation of this normally solitary wasp, don’t be alarmed. It is probably just a bunch of male blue mud daubers gathering together to sleep it off, after a heavy day of “drinking.”
So, rather than having to cover yourself in DEET just to spend the evening on the patio, brave the heat (with water bottle in hand, of course) and spend the daytime hours watching the blue mud daubers prepare their nest for next year’s young. Maybe the media will pick up on wasp that are reducing black widow populations, rather than the dangers of mosquitoes.
Homeowners and horticulture professionals spend time to develop an attractive ornamental bed only to have weeds take over months or a few years later. One common method in the attempt to prevent weeds is to apply a landscape fabric around plants in beds and place a layer of mulch on top to dress it up. The thought is that this barrier on top of the soil will prevent a large number of weeds from emerging. The fabric physically prevents the growth of weeds form the soil below and blocks sunlight from reaching weed seeds. Available fabrics are labeled as porous to allow air and water to move through them and reach ornamental plant roots.
On paper, landscape fabric sounds like a good idea and it may work for a little while. Over time, soil particles and decomposing mulch fill up the porous spaces in the fabric which prevent air and water from reaching plant roots. Even with irrigation or routine rainfall, plant roots often do not receive the needed water and air for healthy growth. Plants may respond by trying to send roots through fabric seams which breaks down the intended weed barrier. Other plants slowly decline or may die quickly due to water stress or lack of sufficient air movement into the soil.
Fabric may initially prevent some weeds but it can also prevent air and water movement. Photo by Beth Bolles, UF Extension Escambia County
Weed seeds also find their way into the mulch that is on top of the fabric from nearby lawns and landscapes. The next thing you know, you have an entire weed crop growing in the mulch on top of your landscape fabric. Perennial weeds such as torpedograss and purple nutsedge eventually grow through fabrics.
Seeds from annuals like Chamberbitter easily get into mulch from surrounding areas and grow on top of fabrics. Photo by Beth Bolles, UF Extension Escambia County
The best place to consider fabric if you want to install it in the landscape is under mulched paths or other areas without ornamental plantings where a synthetic groundcover is needed. In order to have a healthy root environment for your ornamental bed plants, it is best to keep landscape fabric out of these areas.