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.
Homeowners and businesses will often send in plant and insect pictures to the Extension Office. This is a convenient practice for both clientele and Extension Agents, but sometimes it may make diagnosis more difficult and more time-consuming. More often though, a fresh or living specimen is necessary for proper identification.
In an age when high quality pictures can be taken and viewed within milliseconds, plant, disease and insect ID can still take time. Often it is due to the fact we simply don’t know the answer right away and research is required. Sometimes poor picture quality and scale can make the diagnostic process more difficult. To improve identification turnaround time follow these basic steps:
When it comes to taking pictures for diagnostic purposes, more is better. The more pictures depicting angles and magnifications received for a sample the better. If you want a plant identified, take a picture of the entire plant including flowers, leaves, and roots. Take pictures of various stages of spots on leaves, stems, and fruits if you suspect a disease or nutritional disorder. Take pictures from multiple angles and of various body parts for insect identification.
Place an item in the frame of the picture to give a good idea of the size of the specimen through the concept of scale. You could use a ruler, a coin, or even a ballpoint pen. Objects such as coins work well for tiny insects when the measurements on a ruler may be too hard to see in the photo. You can even place the insect on the coin.
A computer keyboard used to show scale for a photo of an aphid. Photo Credit: Julie McConnell – UF/IFAS Extension Bay County
Pay attention to focus on the subject. This is especially true when taking closeup photos and photos of small things with a cell phone camera. Cell phone cameras tend to focus on the background instead of the foreground. Sometimes the quickest solution is to place your hand behind the subject to change the automatic focus and then either leave it in the picture for scale or remove it and snap the picture quickly. It is also important to have a contrasting background such as placing a white or black paper or plastic card behind the subject.
A poor picture of carpetweed growing in a peanut crop.
A good picture of carpetweed using a hand for focus and perspective.
Although it is quicker and easier to email or text plant and insect pictures, the most accurate identification can be accomplished with a fresh sample. Whether you are bringing a sample into your local Extension Office or one of the diagnostic clinics located throughout the state, it is important to follow the guidelines detailed in this publication http://edis.ifas.ufl.edu/sr007.
Extra Credit – If you want to improve you ability to take magnified photos, you may want to build the device featured in the following video “Turn Your Smartphone Into a Digital Microscope”.
Humans have used animal manures to fertilize food crops for thousands of years. Manures are an organic source of plant nutrients and are often a waste byproduct that must be properly managed when raising animals. Today, many farmers and backyard gardeners continue to use animal manures to provide nutrition to their crops. However, a recent experience at our local extension office brought to our attention the need to know what else, besides nutrients, is in the manure used.
A local backyard gardener brought in samples of tomato plants that had strange new growth. She had purchased the tomato plants, along with other vegetable plants, from a local nursery. When she repotted the tomato plants into larger pots, she added horse manure from her own horses to the soil mix. She then noticed this strange growth on the tomatoes, but not in the other vegetable plants that were repotted without adding horse manure. Herbicide damage was one of the first potential causes we suggested, since the new growth was twisted and distorted, a common symptom of plants that have been sprayed by herbicides. The gardener was sure she had not sprayed any herbicides near these plants, or in the pasture where she keeps her horses.
Herbicide damaged tomato plants. Photo by: Mark Tancig
Photos of the tomato plants were shared with other NW District agents and an agriculture agent with livestock and hay producer experience had the probable answer – herbicide damage due to the horses being fed hay from a hayfield that was treated with a particular herbicide. Interestingly, this agent also had experience with these symptoms after their neighbor had similar issues using manure to fertilize the garden.
Herbicides with the active ingredients picloram or aminopyralid are able to cause this kind of unexpected damage to many gardeners’ crops. Herbicides containing these active ingredients are used in hayfields to control broadleaf weeds. These herbicides are especially effective at controlling hard to manage weeds such as thistle, nightshade, and nettle. They also provide long-lasting weed control. Unfortunately, the persistence of these ingredients extends into the hay, and also persists in the manure and urine of animals who eat hay from treated fields. These ingredients pass through the animal unchanged and remain active as an herbicide. Since many vegetable crops are broadleaf plants, the herbicide’s ingredients cause injury.
So what can a farmer or backyard gardener do to prevent this problem? When purchasing hay for livestock, ask the seller if they know whether the hayfield has been treated with herbicides that contain either picloram or aminopyralid. Most herbicides are known by their common names, rather than their chemical name. If they give you a common name or brand name, the active ingredient can be obtained by contacting your local extension office. If the seller can’t tell you, then, as a precaution, do not use the manure to fertilize broadleaf vegetable crops. The same question should be asked if purchasing hay for mulch as well. Composting the manure or hay does not break down the active ingredient, and may even concentrate it.
While we continue to use animal manures to fertilize our crops as our ancestors did, it’s important to remember that many of the tools and products we use today are much more advanced. These advanced products require that we stay informed of all precautions, use them responsibly, and, in this case, inform end users of any precautions. Remember to always read and follow the label and ask questions. And if a science-based answer is what you’re looking for, your local extension office is a good place to go!
Burweed, Soliva Sessilis. – Image Credit: Joseph M. DiTomaso, University of California – Davis, Bugwood.org. Creative Commons License
This spring, lawn burweed has been an especially noticeable problem in lawns. Extension offices throughout Northwest Florida have been fielding many questions and finding solutions to lawn burweed infestations!
On the top of my list of lawn related annoyances is stepping into a patch of burweed, Soliva sessilis, which is in the sunflower family and is also known as spurweed. The leaves are opposite along the stem and sometimes resemble parsley. The main ways in which burweed can irk the casual gardener are sticking to socks, sneaking in with the dog, or littering flower beds with its nuisance. It can also hide in the house and reappear when shoes are removed. This causes pain in both the foot and the ear.
Aside from herbicides, maintaining a healthy vigorous lawn will prevent weeds from taking over. If your lawn is reasonably healthy and only a few instances of this weed exist, try to mechanically remove them and encourage the lawn to outgrow them.
If cultural methods aren’t sufficient, science has given us several options to control this irksome pest. Herbicides containing the active ingredients dicamba, 2,4-D or atrazine are good at controlling burweed as a post emergence control when applied from December through March. Be careful to use reduced rates on centipede and St. Augustine lawns, and never use more than the labeled rate since injury can occur when using these products on these species. Later applications have less effect on burweed because as it matures it is harder to control. Additionally the burs, once present on the lawn, are hard to remove. As the daytime temperatures rise to 90ºF, some of these herbicides may cause lawn damage. Try to keep the spray residue outside of the root zone of desirable plants to avoid injury and always follow label directions.
Be aware that burweed reproduces by seed, so mowing it down will only increase the problem by burying the seed for fall germination. Although we are now in the month of May, control of actively growing burweed might still be warranted if it is still flowering and setting seed. As temperatures warm up burweed will die, as it is a winter annual. In cases where it is already dying, control is not warranted since the natural cycle of winter annuals is concluding.
If an infestation of burweed has occurred this year, take note. The best time to apply pre-emergent herbicides to control burweed is in October. A widely used preemergence product for burweed control is isoxaben, which is sold under the brand name of Gallery as well as others. It prevents the weed from emerging from the ground when it germinates and can be used on St. Augustine, centipede, bahia and zoysia lawns, as well as in ornamental shrub beds. In northwest Florida, this herbicide needs to be applied in October for best results. A second application later in the season might be warranted. For more information about control, please consult this excellent article on lawn burweed management.
The active ingredients mentioned above are present in a variety of ‘trade name’ products* available from your local garden center, farm supply or co-op. Be sure to read label instructions carefully and contact your local extension office for any assistance. I hope all the northwest Florida lawn managers prevent burweed during the upcoming fall so that lawns will be burweed free next spring.
Doveweed (Murdannia nudiflora) is a summer annual weed species that belongs to the dayflower family. Over the last three years, this weed has become an important weed problem in residential lawns and sod production.
This weed has two key characteristics that make it successful. First, its seeds germinate late during the spring when soil temperatures reach 65-70°F. This represents a problem because at this time the effect of preemergence (PRE) herbicides applied in February or March might be too low to provide good doveweed control. Second, the leaves of this weed can be confused with St. Augustinegrass and centipedegrass leaves, and many people do not notice doveweed until the plants are large and are displacing the turf. Doveweed leaves are thick with a shiny rubbery texture. The plant produces creeping stems (stolons), and mowers can break these stolons spreading this weed across the field.
It is very important to keep in mind that doveweed prefers wet areas, so drainage issues or over-watering will favor the establishment and growth of this weed. For this reason, ensuring irrigation is not excessive is a key management practice to control this problem. Another cultural practice that plays a major role on doveweed management is mowing. Mowing too short and too frequently will favor doveweed because its leaves will grow horizontally avoiding the mower blades. Chose a mowing height that allows good ground cover , yet only removes a third of the turf leaf blades.
___________Figure 2. Individual doveweed plant showing flowers, fruits, and stolons with root in nodes.________
Control
Doveweed is easier to control before emergence than when plants are well established. Atrazine is one of the most effective herbicides to control doveweed. A maximum rate of 1 lb. of active ingredient (ai) per acre (A) and no more than 2 lb. ai per year are recommended to achieve both adequate control and avoid turfgrass injury. Atrazine should be applied right before or soon after doveweed emerges to maximize control.
For PRE control, S-metolachlor (Pennant Magnum™), dimethenamid-P (Tower™), and indaziflam (Specticle™) are herbicides that can considerably reduce doveweed establishment, especially if the application is done closer to doveweed emergence timing. These herbicides also provide good control of other important weed species such as crabgrass and goosegrass, which emerge earlier in the spring. In order to control early emerging weeds and doveweed, split applications are preferred. For example, the first application is done at the end of February or early March and the second one 4 to 6 weeks after. In this way, we can extend PRE control until doveweed starts emerging.
If we observe doveweed emerging after PRE applications, we have several postemergence (POST) herbicides that will provide control, as long as the plants are less than 2 inches in size and have not produced stolons. Products containing 2,4-D and dicamba can provide fair control of doveweed. However, repeated applications or applications in combination with other herbicides will be required for adequate control. There are commercial products with formulations that combine 2,4-D or dicamba with other herbicides such as mecoprop-p, carfentrazone (Quicksilver™), thiencarbazone and iodosulfuron (e.g., Celsius™, Tribute Total™). This type of three− or four−way combination can provide enhanced doveweed control. If doveweed has fully displaced the turf in spots, it is probably easier and more effective to kill doveweed with a directed application of glyphosate (RoundUp™) and re-seed or re-sod the area.
Because doveweed seeds can live for several years in the soil, it will take two to three years of continuoous control to eliminate doveweed populations. Although herbicides are useful tools to control doveweed, the most important factor to prevent doveweed problems is to have vigorous healthy turf. Doveweed requires a lot of sunlight, so if the turf effectively shades the ground, doveweed will have a hard time growing and producing new seed.
For more information on managing turf weeds download:
Lawn Burweed, Soliva Sessilis, Closeup – Image Credit: Joseph M. DiTomaso, University of California – Davis, Bugwood.org, Create Commons License
On this bright and sunny early fall morning I was thinking about all of the great gardening opportunities the cooler fall weather is bringing us in the Florida Panhandle. However, my thoughts drifted to the annoyances that the gardeners find when trying to enjoy their lawn or garden.
On the top of my list is stepping into a patch of burweed, which is in the sunflower family and is also known as spurweed. The leaves are opposite along the stem and sometimes resemble parsley. The main ways which burweed can irk the casual gardener are sticking to socks, sneaking in with the dog, or littering flower beds with its nuisance. It can also hide in the house and reappear when shoes are removed. This causes pain in both the foot and the ear.
Aside from herbicides, maintaining a healthy vigorous lawn will prevent weeds from taking over. If you lawn is reasonably healthy and only a few instances of this weed exist, try to mechanically remove them and encourage the lawn to outgrow them.
If cultural methods aren’t sufficient, science has given us several options to control this irksome pest. A widely used pre-emergence product for burweed control is isoxaben, which is sold under the brand name of Gallery as well as others. It prevents the weed from emerging from the ground when it germinates and can be used on St. augustine, centipede, bahia and zoysia lawns, as well as ornamental shrub beds. In northwest Florida, this herbicide needs to be applied in October for best results.
Burweed, Soliva Sessilis. – Image Credit: Joseph M. DiTomaso, University of California – Davis, Bugwood.org. Creative Commons License
Herbicides which contain the active ingredients dicamba, 2,4-D or atrazine are good at controlling burweed as a post emergence control when applied from December through early March. Be careful to use reduced rates on centipede and St. augustine lawns, and never use more than the labeled rate. Later applications have less effect on burweed because as it matures it is harder to control. Additionally the burs, once present on the lawn, are hard to remove. As the daytime temperatures get a few degrees over 80, some of these herbicides may cause lawn damage so immediate application is advised. Try to keep the spray residue outside of the root zone of desirable plants to avoid injury and always follow label directions. Be aware that burweed reproduces by seed, so mowing it down will only increase the problem by burying the seed for fall germination.
The active ingredients mentioned above are present in a variety of ‘trade name’ products* available from your local garden center, farm supply or CO-OP. I hope all the northwest Florida lawns prevent burweed so that the spring lawns will be burweed free. Happy Gardening!
Common Name
Manufacturer / Distributor
Brand Names
Type
Atrazine
Many
Many
Pre and Post Emergent
2,4-D +
MCPP + dicamba (3 way combined herbicide)
Bayer, + others
Many
Post-Emergent
Isoxaben
Dow, Others
Gallery, others are now on the market
Pre-Emergent
*Table reproduced from sections of the 2012 version of University of Florida’s Pest Control Guide for Turf Grass Managers.
