by Daniel J. Leonard | Aug 26, 2021
Nearly everyone likes turfgrass lawns. They’re pretty and green. They filter water, chemicals, and nutrients before they enter our groundwater systems. They provide a recreation spot for people and pets. But lawns also come with maintenance tasks, one of which is weed control. Fortunately, keeping our common Centipedegrass lawns relatively weed free is as simple as smart management and utilizing herbicides effectively. Though the number of herbicides available for purchase can be overwhelming, you only need three to keep weeds at bay – a selective grass herbicide, a strong broadleaf herbicide, and a sedge herbicide!
Dollarweed, one of the toughest broadleaf weeds for homeowners to control. Picture courtesy of Julie McConnell, UF/IFAS.
First up on the essential herbicide list is the selective grass herbicide Sethoxydim. While most folks’ weed focus is centered on broadleaf weeds, grassy weeds like Crabgrass, Bahiagrass, Goosegrass, and others can be just as problematic and make for a very unsightly lawn. Enter Sethoxydim. Cheap and easy to find, Sethoxydim is offered as the active ingredient in many branded products like Fertilome Over the Top Grass Killer, Hi-Yield Grass Killer, and many more. These products control weedy grass species without seriously harming Centipedegrass or broadleaf ornamental trees and shrubs (Centipedegrass may temporarily be yellowed after sethoxydim application but will recover). Not only will it kill out the unwanted grass growing in your Centipede, but it will also remove these weeds from your flower beds!
Second, having a strong broadleaf herbicide on hand is necessary. I say “strong” because many of the homeowner grade products available at garden centers simply don’t have the “juice” to control tough broadleaf weeds like Dollarweed, Doveweed, Virginia Buttonweed, and others. For this job, I prefer to use a commercial grade 3-way product like Celsius WG by Bayer. Celsius WG is a 3-way combination herbicide with a healthy dose of Dicamba as its primary ingredient. Though Dicamba is a notoriously volatile chemical known to cause damage to unintended plants through drift in hot weather, combining it with the two other products in Celsius WG makes it safe to use in lawns, even in the heat of summer. While strong broadleaf herbicides like Celsius WG are expensive on the front end, don’t let that deter you. These products wind up being very cost effective in the long run due to minute mixing rates (one bottle goes a very long way in most residential lawns) and effectiveness – you simply will not need to waste time and money spraying lawn weeds over and over to obtain control like is necessary with lesser products – one or two applications will solve the toughest broadleaf weed problems.
Finally, any good lawn weed control program will include a quality sedge control herbicide. Sedges (often called “nutgrass”) look like grasses but are a completely different category of plants and as such, require specialized herbicide chemistries to achieve control. Sedge weeds prefer wetter areas of lawns, though they can occur in pretty much any lawn site and are very unsightly. For this weed category, there are several options available to homeowners. The one that consistently provides the best control in lawns is Halosulfuron-methyl, the active ingredient in the aptly named product Sedgehammer. Conveniently coming in individually pre-mixed packets for small lawns or a larger bottle when more acreage is to be treated, Sedgehammer couldn’t be easier to mix and use. While Sedgehammer and similar products are extremely effective in controlling various sedge weeds, they tend to work very slowly, and patience is required. Weeds immediately stop growing following a Sedgehammer application, but it can take up to three weeks to notice the sedges dying.
While having and using the above three herbicides can control almost any weed homeowners may encounter in their lawns, it is important to remember that herbicides are not substitutes for proper lawn management. When good cultural practices in lawns are followed, such as mowing at the correct height, only watering when necessary, following UF/IFAS fertilizer recommendations, etc., chemical weed control may not even be necessary in many cases! Also, once the decision to purchase and use chemical herbicides has been made, it is critical that one always read the label before using any herbicide product. This ensures safe and effective use of the product; the label is literally the law!
For assistance in choosing the correct herbicide for your lawn and other lawn care concerns, contact your local UF/IFAS Extension Office! Happy Gardening!
by Sheila Dunning | Aug 26, 2021
Photos by Sheila Dunning
The showy chaste tree makes an attractive specimen as the centerpiece of your landscape bed or in a large container on the deck. Much more of them are being seen since the Florida Department of Transportation has recognized the tree as a desirable median planting. Easy-to-grow, drought resistant, and attractive to butterflies and bees, Vitex agnus-castus is a multi-stemmed small tree with fragrant, upwardly-pointing lavender blooms and gray-green foliage. The chaste tree’s palmately divided leaves resemble those of the marijuana (Cannabis sativa) plant; its flowers can be mistaken for butterfly bush (Buddleia sp.); and the dry, darkened drupes can be used for seasoning, similar to black pepper, making it a conversation piece for those unfamiliar with the tree.
Vitex , with its sage-scented leaves that were once believed to have a sedative effect, has the common name “Chastetree” since Athenian women used the leaves in their beds to keep themselves chaste during the feasts of Ceres, a Roman festival held on April 12. In modern times, the tree is more often planted where beekeepers visit in order to promote excellent honey production or simply included in the landscape for the enjoyment of its showy, summer display of violet panicles.
Chaste tree is native to woodlands and dry areas of southern Europe and western Asia. It will thrive in almost any soil that has good drainage, prefers full sun or light shade, and can even tolerate moderate salt air. Vitex is a sprawling plant that grows 10-20 feet high and wide, that looks best unpruned. If pruning is desired to control the size, it should be done in the winter, since it is a deciduous tree and the blooms form on new wood. The chaste tree can take care of itself, but can be pushed to faster growth with light applications of fertilizer in spring and early summer and by mulching around the plant. There are no pests of major concern associated with this species, but, root rot can cause decline in soils that are kept too moist.
by Daniel J. Leonard | Aug 18, 2021
One of the most conspicuous outcomes from Hurricane Michael was the complete disruption of local lawns and landscapes. Giant holes where tree roots once existed, ruts and compacted ground from clean-up equipment, and formerly shaded acres flooded with fresh sunshine were three very common situations property owners suddenly found themselves faced with. An unforeseen consequence of all this newly bare ground ripe was the intrusion by a variety of very aggressive weeds. One invasive exotic weed that has made itself right at home in many county landscapes following Michael and that I’ve seen lots of lately is Torpedograss (Panicum repens).
Often brought into landscapes with “fill-dirt” and “topsoil” applications or spread through mowing, Torpedograss is an aggressive perennial grass in the same plant family as Bermudagrass and Cogongrass. Like many invasive exotic species, Torpedograss was introduced into the United States in the late 1800’s from its native Africa and Asia as a potential forage crop. Unlike its cousin Cogongrass, the Torpedograss is highly palatable to cattle and so gained a quick following among the ranching community. Unfortunately, over the next century, Torpedograss had left the pasture and turned into one of the biggest pest plants in Florida, ruining many a lawn, taking over 70% of the state’s public waterways, disrupting native marshlands, and costing Florida over $2 million a year to control!
Torpedograss growing in a Calhoun County gravel driveway. Photo courtesy of Daniel Leonard.
Torpedograss spreads rapidly through underground, sharply pointed, white-colored, “torpedo-like” growing tips and can dominate wet or dry areas in short order. The species often hides in lawns when mixed in and mowed with other turfgrasses (especially Zoysiagrass, which it closely resembles), growing unnoticed until infestations are severe and control options are few. This makes scouting for the weed and accurate identification crucial! Torpedograss can be identified by its bluish-green leaf and stem color, hairy leaf edges, stiff overall appearance, distinctive panicle-type flowers, and can grow quickly to 3’ or so in height, spreading indefinitely. Though it initially can resemble other turf species, once you know what you’re looking for, Torpedograss stands out visually amongst its competitors.
After identifying Torpedograss, control methods can be chosen depending on the site it has infested. In lawns, options vary based on turf species. If infestation occurs in the common Centipedegrass and Bahiagrass lawns of the Panhandle, options are few. Products with the active ingredient Sethoxydim (Poast, Fertilome Over the Top, Southern Ag Grass Killer, etc.) can suppress Torpedograss growth in these situations but will not destroy it and are not permanent options. If the area infested is not large, killing the whole spot out with a non-selective herbicide like Glyphosate (Roundup and generics) and then resodding is probably a better option. In Bermudagrass or Zoysiagrass lawns, products with the active ingredient quinclorac (Drive and generics) are very effective at controlling Torpedograss without having to go the “nuclear” glyphosate route. Unfortunately, there are no effective controls for Torpedograss in St. Augustinegrass lawns.
In landscaped beds, Torpedograss is somewhat easier to control. Hand pulling in beds can be effective where new invasions occur but are impractical once the weeds gain a strong foothold. Once that occurs, chemical control is required. In bare or mulched areas away from plants, careful spot spraying in bare areas with a 2-3% glyphosate solution is extremely effective. Where the Torpedograss has grown into and through landscape plants, an “over-the-top” application of fluazifop (Fusilade) will take out the weed without harming most ornamental plant species! (Be sure to check the Fusilade label to make sure your ornamental plant species are safe to apply to!)
Torpedograss is one of the most serious, yet overlooked, invasive plants that occurs in Florida. However, through prevention and control techniques like cleaning mowers when mowing infested areas, accurate identification, and prompt, effective herbicide use, you can keep the weed from taking over your lawn and landscape! For assistance in identifying and controlling Torpedograss and other lawn weeds, contact your local UF/IFAS County Extension office! Happy gardening!
by Pat Williams | Aug 11, 2021
The lawn is a source of pride for most and anything out of the ordinary causes alarm. Now image finding something that looks like lumpy green jelly in your turfgrass and it doesn’t go away. You try raking it, spraying it, covering it, and it still comes back time and time again. One of the things we see in late spring/early summer turf is a reemergence of cyanobacteria (Nostoc), sometimes confused with algae because of green coloring and this remains all summer long.
Dehydrated cyanobacteria in a centipedegrass lawn.
Unlike normal bacteria that needs a food source, cyanobacteria contains chlorophyll and produces its own food source through photosynthesis which allows it to grow on bare sandy soils, fabric mats, concrete sidewalks, plastic, and yes even your lawn. Besides the green pigment, it also produces a blue pigment and is why we call it cyanobacteria which means blue-green bacteria. In addition to photosynthesis, cyanobacteria can also fix nitrogen, and are believed to produce cyanotoxins and allelopathic compounds which can affect plant growth around them.
Cyanobacteria are considered one of earth’s oldest organism and they have tremendous survival capabilities. They can dry out completely, be flat, flaky, black-green dried particles in your lawn and once rehydrated, spring back to life. If you happen to notice it spreading throughout your yard, remember that pieces of the organism can stick to your wet shoes or lawnmower tires and be transported unintentionally.
The question then becomes how to control the cyanobacteria and reclaim your turfgrass. The first solution is to have a healthy lawn. Cyanobacteria likes poorly-drained compacted soils. This same condition is unfavorable to turf growth and why you end up with bare spots and establishment. Reduce soil compaction by using a core aerator, and then adding organic matter. This will increase drainage, gas exchange, and encourage microorganism populations which I like to call soil pets. Spike aerators only push the soil particles aside and don’t really loosen as well. Try to reduce low lying areas in the lawn where water sits after rainfall and irrigation. You might have to till and reestablish those areas of the yard.
The same cyanobacteria pictured above 24 hours after being rehydrated in a petri dish of standing water.
Controlling the amount of water Mother Nature gives us and humidity levels during summer is not possible, but you can control your irrigation whether it be automatic (sprinkler system) or hand-watered. During the rainy season, you should be able to get by with only rainfall and shut off your system. If needed during extended dry weeks, it is easy enough to turn the system back on. It is thought that cyanobacteria likes phosphorus which is another reason to use little to no phosphorus in your lawn fertilizers.
As you begin to rid your lawn of cyanobacteria, remember when fully hydrated it forms a slippery surface so be careful walking on it. Cultural practices will be more effective in controlling the spread versus using chemical methods. Cultural solutions are safer for your lawn, yard and all of the wildlife that visits. If you need help with your cyanobacteria, please contact your local Extension office and we are always happy to assist.
A special thanks to Dr. Bryan Unruh, UF/IFAS for his assistance in identifying the cyanobacteria.
For additional information, please read the sources listed below.
Biology and Management of Nostoc (Cyanobacteria) in Nurseries and Greenhouses. H. Dail Laughinghouse IV, David E. Berthold, Chris Marble, and Debalina Saha
Rain, Overwatering Can Cause Slippery Algae to Pop Up in Turfgrass. C. Waltz
Nostoc. N.J. Franklin
by Stephen Greer | Aug 11, 2021
One big goal of establishing a home lawn and landscape is to enjoy an attractive setting for family and friends, while also helping manage healthy soils and plants. Soil compaction at these sites can cause multiple problems for quality plants establishment and growth. Soil is an incredibly important resource creating the foundation for plants and water absorption.
Photo courtesy: Stephen Greer, UF IFAS
Soils are composed of many different things, including minerals. In Florida, these minerals often include sand of differing sizes and clay in the northern area of the counties in the panhandle of Florida. Soil is also composed of organic matter, nutrients, microorganisms and others. When soil compacts, the air spaces between the sand or clay are compressed, reducing the space between the mineral particles. This can occur anytime during the landscape and lawn construction phase or during long term maintenance of the area with equipment that could include tractors, mowers, and trucks.
What can be done to reduce soil compaction? There are steps that can be taken to help reduce this serious situation. Make a plan on how to best approach a given land area with the equipment needed to accomplish the landscape of your dreams. Where should heavy equipment travel and how much impact they will have to the soils, trees, and other plants already existing and others to be planted? At times heavy plywood may be needed to distribute the tire weight load over a larger area, reducing soil compaction by a tire directly on the soil. Once the big equipment use is complete, look at ways to reduce the areas that were compacted. Incorporating organic matter such as compost, pine bark, mulch, and others by tilling the soil and mixing it with the existing soil can help. Anytime the soil provides improved air space, root will better grow and penetrate larger areas of the soil and plants will be healthier.
Even light foot traffic over the same area over and over will slowly compact soils. Take a look at golf course at the end of cart paths or during a tournament with people walking over the same areas. The grass is damaged from the leaves at the surface to the roots below. Plugging these areas or possibly tilling and reestablishing these sites to reduce the compacted soils may be necessary.
Photo courtesy: Stephen Greer, UF IFAS
Water absorption is another area to plan for, as heavy rains do occur in Florida. Having landscapes and lawns that are properly managed allow increased water infiltration into the soil is critically important. Water runoff from the site is reduced or at least slowed to allow the nutrient from fertilizers used for the plant to have more time to be absorbed into the soil and taken up by the plants. This reduces the opportunity for nitrogen, phosphorus, and other nutrients to enter water areas such as ponds, creeks, lagoons, rivers and bays. Even if you are miles from an open water source, movement of water runoff can enter ditches and work their way to these open water areas, ultimately impacting drinking water, wildlife, and unwanted aquatic plant growth.
Plan ahead and talk with experts that can help with developing a plan. Contact your local Extension office for assistance!
