by Daniel J. Leonard | Jul 22, 2021
If you’ve taken care of your yard properly from spring green-up to now (mid-July), you might think you can comfortably coast into the cool temperatures of fall without any problems. You would be mostly right, save for one extraordinarily tough weed that waits until the depths of summer to rear its troublesome head: Doveweed (Murdania nudiflora).
Doveweed seedlings just emerged on July 9, 2021. Photo courtesy of Daniel Leonard.
Doveweed is an insidious invader of Panhandle lawns. In the Panhandle, Doveweed germinates (sprouts) long after most other summer annual weeds, from late May-June when soil temperatures reach ~70°F. This allows it to sneakily avoid spring pre-emergent herbicide applications and even early summer post-emergent applications that target common weeds like Florida Pusley, Spurge species, and others. Doveweed also looks an awful lot like many of our common lawn turfgrasses, especially Centipede and St. Augustine Grass. It possesses thick, shiny, grass-like foliage and even grows in a spreading, low to the ground fashion. This mimicry causes many homeowners to not realize there is a problem until it’s too late. Once Doveweed is mature and displaying its characteristic purple flowers, it is very difficult to control. Finally, Doveweed is extremely tough and aggressive, particularly thriving in moist areas of the lawn. In these areas, Doveweed can easily outcompete the desirable turfgrass and, without intervention by you, will soon have the whole lawn to itself.
Controlling Doveweed is no easy task and requires a combination of practices to keep it out of your lawn. The first line of defense against any weed, Doveweed included, is through proper cultural practices. In turfgrass lawns, this means ensuring that you mow your lawn regularly and at the proper height (2.5” or so for Centipedegrass), keeping the lawn irrigated during droughty periods, fertilizing based on a soil test, etc. Being diligent in the above tasks will go a long way to ensuring that your turfgrass is healthy and better able to ward off a Doveweed invasion. However, even when homeowners maintain their turf perfectly, chemical herbicides are usually required to keep Doveweed at bay.
Doveweed patch in St. Augustine Sod.
While many commonly used homeowner herbicides are not effective on Doveweed, there are several quality options at your disposal.
- Doveweed is most easily controlled with preemergent herbicides, specifically one of the following: Atrazine, Pennant Magnum (S-metolachlor), Tower (dimethenamid), and Specticle (indaziflam). The issue with pre-emergents is that most folks shelve them after spring application in February or March. Since these products lose their efficacy after 4-6 weeks, Doveweed’s emergence in May is undeterred. To obtain control on Doveweed with these products, split the spring application and apply once in late Feb/early March and again in mid-late April.
- Doveweed can also be controlled by post-emergent herbicides after it is up and growing, though multiple applications may be required. The most effective formulations contain a combination of 2,4-D or Dicamba and other herbicides. While most of these products have at least fair efficacy on Doveweed, stronger, more expensive products like Celsius, Tribute Total and others provide better results.
- If Doveweed has already displaced turfgrass in large areas of your lawn, you may unfortunately be better off to make an application of a non-selective herbicide like glyphosate (Roundup), kill out the entire area of infestation and start over by resodding.
While Doveweed is a major problem in Panhandle lawns, it doesn’t have to be in yours! By keeping your turf healthy with proper cultural practices and making timely applications with effective herbicides, your lawn can be a Doveweed free zone! For assistance in Doveweed identification in your lawn, help choosing herbicides and calculating application rates, or any other horticultural information, contact us at the UF/IFAS Calhoun County Extension office! Happy Gardening!
by Larry Williams | Mar 25, 2021
As a boy in a small town in Georgia we had a St. Augustinegrass lawn. My dad started the lawn before I was born. That lawn was still doing fine when I left for college at age seventeen. I don’t remember weeds in the lawn during summer months. I do fondly remember winter “weeds” in that lawn.
To see clumps of winter annuals in our yard and in neighbors’ yards was a natural part of the transition from winter to spring. They added interest to what
Blue Easter egg hidden in chickweed. Photo credit: Larry Williams
would have been a plain palette of green. It was expected to see henbit with its square stiff stems holding up a display of small pinkish purple flowers in late winter and early spring. A clump of henbit was a great place to hide an Easter egg, especially a pink or purple one.
Wild geranium, another common winter annual, offered another good hiding place for Easter eggs with its pink to purple flowers. Large clumps of annual chickweed would nicely hide whole eggs. Green colored eggs would blend with chickweed’s green leaves.
Pink Easter egg hidden in crimson clover & hop clover mix. Photo credit: Larry Williams
Crimson clover with its reddish flowers, hop clover and black medic with their bright yellow flowers were good hiding places for Easter eggs. Plus clovers add nitrogen back to our soils.
I never remember my dad using any weed killer, he rarely watered. The lawn was healthy and thick enough to be a deterrent to summer weeds. But during fall and winter as the lawn would naturally thin and go dormant, winter annual weeds would run their course.
I’ve heard that the sense of smell provides our strongest memories. I remember the first mowing of the season with the clean smell of chlorophyll in the spring air. It was refreshing. Once mowed and as the heat took its toll, by late April or mid-May, these winter annual weeds were gone. What was left was a green lawn to help cool the landscape as the weather warmed. The lawn was mowed high as St. Augustine should be, played on and typically not worried with.
Most people have winter weeds in their lawns that let us know spring is near. Perhaps we worry too much with these seasonal, temporary plants that may have wrongly been labeled as weeds. Besides, how long have we been doing battle with these weeds and they are still here. Most lawns have countless numbers of winter annual seeds awaiting the cooler temperatures and shorter days of early winter to begin yet another generation. By May they are gone.
by Matthew Orwat | Mar 25, 2021
Stinkbugs and their relatives are not always problematic in the flower or vegetable garden, but when they become so, they can suck the life out of our fruits and vegetables, create ugly abrasions, and destroy flowers such as roses.
Over-wintering adult leaffooted bug emerging from hibernation . Image Credit Matthew Orwat, UF / IFAS Extension
The green stink bug Acrosternum hilare (Say). Image and caption credit EDIS, Dr. Russ Mizell
What is a Stink Bug?
The stink bug (Pentatomidae family) is a major garden pest of a variety of fruits and vegetables including squash, peppers, tomatoes, peaches, plums, pecans and a variety of other edibles. They are known as a “piercing and sucking” insect because that’s the way they feed, by using their mouth, or proboscis, just like a needle to pierce the fruit and suck out the juices. This feeding leaves a damaged area of the fruit which may develop discoloration, rot or fungal disease and render the fruit unsaleable or inedible.
Who are “their relatives”
The leaf footed bug, Leptoglossus phyllopus (L), is a relative of the stinkbug and feeds in the same way, has a similar lifecycle and causes similar damage. They are usually slightly larger and have “leaf like” appendages on their legs which are their namesake.
What is their lifecycle?
In Florida, overwintering adult stink bugs will place a clutch, or tight group of eggs, on a host plant early in the growing season. If their preferred plant is not available, they use a variety of weeds and grasses to lay eggs upon and provide food for their young. After eggs hatch, they go through several nymph stages before they finally reach the adult stage. Stink bugs have multiple generations in a year, often four to five. They readily move to find preferable food sources and might appear in a garden without warning to feed and cause destruction.
Nymph of the leaffooted bug, Leptoglossus phyllopus (L.). Photograph by Lyle J. Buss, University of Florida.
How are they best controlled?
First of all, many stink bugs use weeds as host plants to gather and feed upon, so controlling weedy plants around vegetable and fruit gardens might limit their numbers. If stink bugs are a major problem, planting trap crops, such as sunflowers, is beneficial. Stink bugs prefer to feed on sunflowers more than some other vegetables. This situation can be used to the gardener’s advantage by mechanically killing or spraying stink bugs on trap crops while avoiding treating food crops with pesticides. More information on trap cropping can be found here.
Additionally, stink bug traps are available. These mechanically trap stink bugs, thus reducing their numbers in the garden, but need to be monitored and serviced regularly. Several species of parasitic Tachinid flies are also predators of stink bugs. These flies lay their eggs on adult stink bugs. The fly larva use the bug as a buffet, slowly killing the bug.
Stink bugs are difficult to control with insecticides, but some measure of control can be achieved at their nymph stage with various approved fruit and vegetable insecticides containing pyrethrins. These products are readily available at local garden centers and feed & seed stores.
For more information, please check out the following resources:
by Pat Williams | Oct 21, 2020
Normally, you will have one of four answers: “yes”, “no”, “I don’t know” or “what are super bugs?” The answer to the last one is an insect or other pest that has become resistant to chemical treatments through either natural selection (genetics) or an adaptive behavioral trait.
The next question is do you treat insect or pest problems at home with a purchased EPA registered chemical (one purchased from the nursery or other retailer)? If you answered yes, then the next question is how many times in a row do you apply the same chemical? If you only use one chemical until the product is used up, then you might be creating super bugs. Do you ever alternate chemicals and if you answer yes, do you understand chemical Modes of Action (how the pesticide kills the pest)? If you do not, then chances are the rotating chemicals might act in the same way. Thus, you are creating super bugs because in essence you are applying the same chemical with different labels.
Click on image for a larger view. Taken from https://edis.ifas.ufl.edu/in714.
One of the first ways to reduce creating super bugs is to practice Integrated Pest Management (IPM). The very last step of an IPM philosophy is chemical control. You should choose the least toxic (chemical strength is categorized by signal words on the label: caution, warning, and danger) and most selective product. A chemical label advertising it kills many pests is an example of a non-selective chemical. You want to choose a chemical that kills your pest or only a few others. In Extension education, you will always hear the phrase “The label is the law.” To correctly purchase a chemical, you must first correctly identify the pest and secondly the plant you want to treat. If you need help from Extension for either of these, please contact us. Before purchasing the chemical, always read the whole label. You can find the label information online in larger print versus reading the small print on the container.
IRAC phone app.
You now have the correct chemical to treat your pest. Wear the recommended personal protective equipment (PPE) and apply according to directions. If your situation is normal, the problem is not completely solved after one treatment. You might apply a second or third time and yet you still have a pest problem. The diagram explains why you still have pests or more accurately super bugs.
Now the last question is how do we really solve the problem given that chemicals are still the only treatment option? A bit more work will greatly help the situation. You need to download the Insecticide Resistance Action Committee (IRAC) guide and find the active ingredient on your chemical label (http://edis.ifas.ufl.edu/pi121 or https://irac-online.org/modes-of-action/ and select the pdf). If you are like me, you can just download the IRAC MoA smartphone app and type in the active ingredient; otherwise, Appendix 5 in the pdf has a quick reference guide. Either way, you will know the Group and/or Subgroup. A lot of commonly purchased residential chemicals fall within 1A, 1B or 3. The successful treatment option is to select chemicals from different group numbers and use them in rotation. If you start practicing this simple strategy, your treatment should be more successful. Then when someone asks if you are creating super bugs, your answer will be no.
If you have any questions about rotating your chemical Modes of Action, please contact me or your local county Extension agent. For more resources on this topic, please read Managing Insecticide and Miticide Resistance in Florida Landscapes by Dr. Nicole Benda and Dr. Adam Dale (https://edis.ifas.ufl.edu/in714).
by Daniel J. Leonard | Oct 14, 2020
Article by Jessica Griesheimer & Dr. Xavier Martini, UF/IFAS North Florida Research and Education Center, Quincy
Dioscorea bulbifera, commonly known as the air potato is an invasive species plaguing the southeastern United States. The air potato is a vine plant that grows upward by clinging to other native plants and trees. It propagates with underground tubers and aerial bulbils which fall to the ground and grow a new plant. The aerial bulbils can be spread by moving the plant, causing the bulbils to drop to the ground and tubers can be spread by moving soil where an air potato plant grew prior. The air potato is commonly confused with and mistaken as being Dioscorea alata, the winged yam which is also highly invasive. The plants look very similar at first glance but have subtle differences. Both plants exhibit a “heart”-shaped leaf connected to vines. The vines of the winged yam have easily felt ridges, while the air potato vines are smooth. They also differ in their aerial bulbil shapes, the winged yam has a long, cylinder-shaped bulbil while the air potato aerial bulbil has a rounded, “potato” shape (Fig. 1).
In its native range of Asia and Africa, the air potato has a local biocontrol agent, Lilioceris cheni commonly known as the Chinese air potato beetle (Fig. 2). As an adult, this beetle feeds on older leaves and deposits eggs on younger leaves for the larvae to later feed on. Once the larvae have grown and fed, they drop the ground where they pupate to later emerge as adults, continuing the cycle. The Chinese air potato beetle will not feed on the winged yam, as it is not its host plant.Current methods of air potato plant, bulbil, and tuber removal can be expensive and hard to maintain. The plant is typically sprayed with herbicide or is pulled from the ground, the aerial bulbils are picked from the plant before they drop, and the underground tubers are dug up. The herbicides can disrupt native vegetation, allowing for the air potato to spread further should it survive. If the underground tuber or aerial bulbils are not completely removed, the plant will grow back.
The Chinese air potato beetle is currently being evaluated as a potential integrated pest management (IPM) organism to help mitigate the invasive air potato. The beetle feeds and reproduces solely on the air potato plant, making it a great IPM organism choice. During 2019, we studied the Chinese air potato beetle and its ability to find the air potato plant. It was found the beetles may be using olfactory cues to find the host plant. Further research is conducted at the NFREC to increase natural aggregation of the beetles on air potato to improve biological control of the weed.
Chinese Air Potato Leaf Beetle.
If you have the air potato plant, or suspect you have the air potato plant, contact your local UF/IFAS Extension Agents for help!
by Mary Salinas | Sep 8, 2020
Perennial milkweed, Asclepias perennis, with oleander aphids; notice the brown aphid mummies that have been parasitized. Photo credit: Mary Salinas UF/IFAS Extension.
Milkweeds are appreciated for their beauty, but often we cultivate it for the benefit of the monarch butterflies who lay their eggs only on this plant genus. Avid butterfly gardeners want the monarch caterpillars to eat up the milkweed and become beautiful butterflies. Often instead, thousands of aphids show up and compete for space on the plants. These bright yellow aphids are known as oleander aphids.
Just how do aphids build up their populations so quickly? It seems that one day you have a small number on a few plants and then a few days later, thousands are all over your milkweed. Oleander aphids have a few advantages for quickly building their populations:
- All oleander aphids are female and do not need to mate to produce their young
- Aphids give birth to live young who immediately start feeding on the plant
- Aphids start reproducing when they are 4 to 10 days old and keep reproducing during their one-month life span
- When populations get heavy or the plant starts to decline, winged individuals are produced to migrate to new areas and plants.
Parasitic wasp and aphid mummies. Photo credit: University of California.
What can or should you do to control this pest?
One option is to do nothing and let the natural enemies come in and do their job. One of the best is a very tiny wasp that you will likely never see. This parasitoid lays its eggs only inside aphids. The wasp larva feeds on the inside of the aphid and turns it into a round brown ‘mummy’ and then emerges when mature by making a round hole in the top of the aphid. Look closely with a hand lens at some of those brown aphids on your milkweed and you can see this amazing process. Another common predator I see in my own garden is the larvae of the hover fly or syrphid fly. You will have to look hard to see it, but it is usually there. Assassin bugs and lady beetles also commonly feed on aphids. The larvae of lady beetles look nothing like the adults but also are voracious predators of aphids – check out what they look like.
Lady beetle larva feeding on aphid on tobacco. Photo credit:
Lenny Wells University of Georgia Bugwood.org.
If you think your situation requires some sort of intervention to control the aphids, first check carefully for monarch eggs and caterpillars, keeping in mind that some may be very small. Remove them, shoo away any beneficial insects, and spray the plant completely with an insecticidal soap product. Recipes that call for dish detergents may harm the waxy coating on the leaves and should be avoided. The solution must contact the insect to kill it. Always follow the label instructions. Soap will also kill the natural enemies if they are contacted. One exception is the developing wasp in the aphid mummies – fortunately, they are protected inside as the soap does not penetrate. Oils derived from plants or petroleum can serve the same purpose as the insecticidal soap.
Syrphid fly larva and oleander aphids. Photo credit: Lyle Buss, University of Florida.
You also can squish the aphids with your fingers and then rinse them off the plant. If you only rinse them off, the little pests can often just crawl back onto the plant.
There are systemic insecticides, like neonicotinoids, that are taken up by plant roots and kill aphids when they start feeding on the plants. However, those products also kill monarch caterpillars munching on the plant and harm adult butterflies, bees, and other pollinators feeding on the nectar. So those products are not an option. Always read the product label as many pesticides are prohibited by law from being applied to blooming plants as pollinators can be harmed.
In the end, consider tolerating some aphids and avoid insecticide use in landscape.
Happy butterfly gardening!
