Fall oak tree leaves abound and can be recycled as landscape mulch. Photo credit: Larry Williams
Weed control is not top on my list as a reason to use mulch. There are weeds that can push through mulch such as nutsedge (nutgrass) or that can germinate and grow in the mulch. But done correctly, mulching plant beds and gardens can help inhibit some weeds. Tree leaves can be used as a mulch.
In addition to weed control, mulch provides other benefits. It can make landscapes look more attractive. It keeps roots evenly moist, acts to insulate roots from extreme heat and cold and can help decrease loss of soil from wind and water erosion. Mulch serves as a barrier to some soil-borne diseases, especially in the vegetable garden. And, as organic mulch breaks down, it improves the soil’s fertility, aeration, structure and drainage.
Tree leaves make good mulch. They can be placed on the soil surface beneath and around shrubs, trees, perennials, annuals and vegetables.
Fall leaves are abundant. Some people feel overwhelmed by the volume. One resident reported raking more than 100 large bags of leaves from his half-acre property. One large oak tree can contain over 250,000 leaves!
Tree leaves can be placed in landscape beds or around vegetables “as is” or chopped up with a shredder or mower into smaller pieces and then spread around vegetables, shrubs and trees. Mixing leaves from several different species of trees can make better leaf mulch. Leaves of the same size tend to mat together and produce a shingling effect that can shed water and reduce gas exchange in the soil. Shredded leaves stay seated better on the landscape than whole leaves.
A mulch layer three inches deep after settling is enough for most plants. If possible, extend the mulched areas out to the outermost leaves (called the drip line) and beyond. And be sure to pull the mulch back a few inches from the main trunk. Never pile mulch around the trunk.
Using those fallen tree leaves as mulch recycles a natural resource and saves you money, enriches your soil, fertilizes your plants and keeps them out of the local landfill.
So, instead of putting all those leaves curbside in plastic bags to be hauled off, use them to benefit your landscape, which may include less weeds.
For additional information on landscape/garden mulch, contact the UF/IFAS Extension Office in your County or access the following sites.
Most lawn weeds are annoying, appearing in unwanted places and numbers, but few actually cause physical harm like the pest plant Lawn Burweed (Soliva sessilis)! This infamous small, spreading winter weed’s seeds generally germinate when temperatures begin to cool in the fall (late October-November). Burweed then grows mostly unnoticed through the winter until spring, when it then produces the hard, spiny burs that contain the plant’s seeds and the plants finally die. Once the burs have formed, Burweed’s presence makes walking on newly greened-up spring turf extremely painful for pets and people (barefoot of course, the burs aren’t large enough to puncture shoe soles). At this point of the plant’s life, once it has made its unwanted presence known, control is not feasible as the Burweed plants have set seed, ensuring a new crop next year, and killing the remaining foliage doesn’t remove the burs. What is a homeowner to do?
Newly germinated Lawn Burweed. Photo courtesy of the author.
Fortunately, Lawn Burweed is relatively easy to control chemically if one pays close attention to seasonal changes and uses herbicides (either pre-emergent or post-emergent herbicides) effectively.
Pre-emergent Herbicide Options: The first chemical control option for Lawn Burweed is a timely application of the pre-emergent herbicide Isoxaben (sold under various brand names at most farm or garden stores) to prevent Burweed seeds from germinating, greatly reducing plant populations. However, pre-emergent Isoxaben applications must be made before the plants sprout and begin to grow to be effective. For Burweed, this generally means application in October, once nighttime temperatures dip into the 55-60 degrees F range for several nights in a row, as consistent temperatures in this range give Burweed seeds the signal to germinate. Though we’re already past the point of pre-emergent herbicides being an option for control this year, homeowners should plan to include this method in their Lawn Burweed control plan for fall 2020!
Post-Emergent Herbicide Options: If you haven’t already used a pre-emergent herbicide this fall for Burweed control, you must turn to post-emergent options. Like pre-emergent herbicides, timing is critical if you want your post-emergent applications to work! These herbicides are most effective when Burweed plants are young, small, vigorously growing, and haven’t set burs yet. Successful post-emergent applications may be made from December-early February before burs harden. Unlike pre-emergents, where there is only one strong option for Burweed control, many post-emergent herbicides exist that are extremely effective! When shopping, look for products containing the following active ingredients:
Lawn Burweed around 10 days after emergence. Photo courtesy of author.
Atrazine – sold under many brand names and safe in Centipede, St. Augustine, & Bermudagrass. Do not use in Zoysia or Bahiagrass lawns.
Dicamba, Mecoprop, 2,4-D – commonly sold in three-way formulations through many brand names. Generally safe in Centipede, St. Augustine, Bermuda, Zoysia, & Bahiagrass lawns.
Metsulfuron – sold under several brand names and safe in Centipede, St. Augustine, Zoysia & Bermudagrass. Do not use in Bahiagrass. Be careful if used around ornamentals.
Thiencarbazone, iodosulfuron, dicamba – sold as Celsius WG from Bayer. Safe in Centipedegrass, Zoysiagrass, Bermudagrass, and St. Augustinegrass. Do not use in Bahiagrass.
Lawn Burweed control with of all the above-listed herbicides will be most effective with a follow-up application 10-14 days later.
Note: With the exception of the Thiencarbazone, iodosulfuron & dicamba mixture (Celsius), do not apply any of these post-emergent herbicides during spring turf green up.
Gardeners are always fighting the endless weeds that pop up in landscape and flower beds. When homeowners put in a new landscape bed and want to prevent future weed invasions, many think that putting down landscape fabric is a great way to keep the weeds from emerging and protect the newly planted trees, shrubs or perennials.
An example of failure of landscape fabric to control weeds less than 2 years after planting. Note the peeking through at the edges. Photo credit: Mary Salinas, UF/IFAS Extension.
Is Landscape fabric a good choice? Why or why not?
If landscape fabric is not covered up, sunlight will degrade the fabric. When mulch is placed on top of the fabric (and we all do want to cover it up – the fabric is not very attractive) the mulch breaks down into soil. Inevitably, weed seeds blow in and settle and germinate and grow on top of landscape fabric. And here you are with a weed problem. Weeds also find their way into the openings cut for desirable plants and along the edge of the fabric.
Landscape fabric is porous when put in place to allow water to pass through, but as time passes, the pores can get clogged and water penetration is restricted – rain and irrigation runs off and the plants you meant to protect are not getting the water they need.
Maybe the worst effect is that the landscape fabric creates unfavorable soil conditions. A healthy soil is key to good plant health. One thing soil needs to have is an exchange of carbon dioxide and oxygen between the soil and the atmosphere. Recent studies from Washington State University demonstrated that gas movement between the soil and the atmosphere is restricted about 1,000 times more when landscape fabric is present than when areas have only wood mulch.
So, if landscape fabric is not a good choice, what is?
Mulch made from wood, bark, fallen leaves and pine needles. See Gardening Solutions: Mulch for sustainable ideas.
For a state that receives around 60” of rainfall a year, it is sure dry in Florida right now! In the Panhandle, the majority of our annual rainfall occurs in in bunches during winter and early spring via near-weekly cold fronts, in the mid-summer as a result of afternoon thunderstorms, and periodically in late summer/early fall if a tropical system crosses our path. Mixed in, however, are two distinct, historically dry periods: the first one in April through mid-May (contrary to popular myth, if we have May flowers, they’re gonna have to make it without April showers) and the second right now in September and October. The prolonged second dry period that we’re experiencing now makes it difficult to manage the mostly unirrigated, low-input turfgrass common in rural Panhandle lawns and pastures. It is critical to enter these expected droughts with healthy turf and remembering to employ 3 simple management tips when it quits raining (although you should follow them year-round ideally) can greatly increase your turf’s resiliency!
Unirrigated Centipdedegrass turf showing drought stress- Photo courtesy of the author.
Water Wisely – The average Florida turfgrass requires ¾-1” of water per week and we generally achieve that through rainfall. However, in our droughty months, supplemental irrigation can be a lawn saver, particularly in high traffic or more stressed areas of the yard. I realize that many of you, myself included, maintain large lawns without irrigation systems and it’s impossible to keep all your lawn well-watered during drought, but you can maintain the areas around your home, hardscapes and landscaped beds with the highest impact/visibility nicely! In these areas, put down no more than ¾” of water per irrigation event, a ballpark number that ordinarily allows the turf root zone to become saturated. Measuring your sprinkler’s water output is easily done by setting several straight-sided cans (tuna or cat food containers work great) under the sprinkler and timing how long it takes to achieve 3/4”. You might be surprised how much water you waste by leaving a sprinkler running for an hour or more!
Apply Herbicides Appropriately – Herbicides are a great item to have in the turf care toolbox, but if used incorrectly can be a waste of time and money at best, harmful to your turf at worst! Once turf and associated weeds become drought stressed (turning bluish gray, obvious wilting, leaves curling, etc.), it is too late for weed control with herbicides. There are a couple of reasons for this. First, when plants get stressed, they slow or stop their growth and focus on survival. This survival response prevents herbicides from being taken up properly and ultimately causes ineffectual weed control. Also, many herbicides specifically state on the product label that they should not be applied during certain conditions (drought, temperatures above 85-90 degrees, etc.). It is critical that one adhere to these label directions as applying the incorrect product in hot and dry conditions can cause volatility, drift to non-target plants, and in some cases, toxicity to turf you’re treating in. When it’s droughty like it is now, leave the herbicides in the chemical shed to prevent wasting your time and money and potentially damaging non-target plants!
Unirrigated Centipedegrass turf showing drought stress – photo courtesy of the author
Raise that Deck – Finally, one of the most important turf management strategies during an extended drought is to reduce mowing and raise your mower’s cutting height when/if you do mow. As mentioned above, plants are already stressed during a drought and physically chopping off a chunk of the turf plant stresses it further, causing an energy-intensive wound response when the plant is actively conserving resources for survival. Therefore, if you just HAVE to mow, raise the cutting height as high as possible to make the smallest injury possible on the grass and keep your mower blades sharp to ensure a clean cut, which will heal easier and require a smaller energy response from the plant.
During droughts like the one we’re currently in, there isn’t one silver bullet to keep your non-irrigated turf looking good. However, there are several strategies you can use throughout the year to get your lawn through dry times. Remember to water ¾”-1” per week when you can, where you can. Before you water, calibrate your sprinkler to ensure you put out enough water and don’t waste your time and inflate your utility bill by putting out too much! Reduce or eliminate use of herbicides as they are ineffective during stress periods and can harm your turfgrass. Finally, reduce or eliminate mowing and if you must mow, raise the deck! If you have any questions about getting your turf through the drought or other horticultural or agronomic topics, please contact your local UF/IFAS Extension Office!
Weeds identification and management is still one of the most common questions we receive at the local UF IFAS Extension office. Learn about the chamberbitter weed that can grow in turf and ornamental beds and the multi faceted approach that is necessary for management In the Garden with Beth Bolles, UF IFAS Extension Escambia County.
“There are these weeds spreading all over my yard. They have little round leaves that are real close to the ground and creep in every direction. I keep trying to get rid of them by mowing my grass shorter, but they are killing my grass. What are they and how do I get rid of them?” Here at the Extension office, this is a conversation I have had nearly daily for the past month. We are here to help with identification and control of many landscape problems, including weeds.
However, my first word of advice is to change the mowing practice. Short, spreading weeds cannot be mowed out. You need to do just the opposite. Mowing as high as possible (3-4”) will help to reduce weeds by shading them out, therefore, reducing their spread.
In every instance, the weeds have been common lespedeza (Kummerowia striata (Thunb.) Schind syn. Lespedeza striata) and/or prostrate spurge (Euphorbia maculata syn. Chamaesyce maculata). Both grow close to the ground with a spreading habit. Both have small, rounded leaves and produce small, light-colored flowers. But, if you look close, there are significant differences that will help with identification.
Common lespedeza, also known as Japanese clover, is prostrate summer annual that forms 15-18 inch patches. The stems are wiry. It has dark green trifoliate (arranged in threes) leaves with three oblong, smooth leaflets. Leaflets have parallel veins nearly at right angles to a prominent mid-vein. Its leaves have smooth edges and a short spur at the tip of each leaflet. Flowers appear in late summer with small pink to purple, single flowers found in leaf axils on most of the nodes of the main stems. As common lespedeza matures, the stems harden and become woody.
Prostrate spurge is a summer annual broadleaf weed that spreads by seed. The leaves are oval in shape, small, and opposite along the stem. As it matures, a red spot may form in the center of the leaf, earning it the common name spotted spurge. Another distinct characteristic is the stem contains a milky sap that oozes when the stem is broken. Light pink to white-colored flowers appear from early-summer through the fall.
Both are annual,broadleaf weeds, so there are several post-emergent herbicides available to kill the ones present. Don’t forget the pre-emergent herbicide application in late winter though. These weeds can drop plenty of seed. The importance of knowing which weed you have is more about the message they are trying to send you. These weeds can indicate other issues that may be part of the reason the grass is thinning and allowing the weeds to take over in the first place.
Common lespedeza is a legume. It thrives when water is plentiful and soil nutrients are low. If this is the weed “taking over” your yard, you need to get a soil test and evaluate your watering habits. Improving fertility and reducing soil moisture will naturally weaken common lespedeza.
If your thin patches of declining grass are being replaced with spurge, it may be time to submit a sample for a nematode assay. Research has shown that spurge is a weed that can thrive with high populations of nematodes. Turfgrass species are easily harmed by nematodes (microscopic roundworms that imbed into and on grass roots). If the assay indicates harmful population levels, unfortunately there are few options for reduction of the nematodes. However, several ornamental plants are tolerant. So, you may need to consider creating a landscape bed area rather than continuing to battle poor-looking grass.
Weeds can serve as indicators to soil conditions that may need to be addressed. Learning to identify weeds may teach you more than just their names.
