Timing is Everything when Controlling Lawn Weeds

Timing is Everything when Controlling Lawn Weeds

Hot, summer months are not the time to be using most lawn herbicides.

One issue is the heat of summer. Most lawn herbicide labels include statements such as the following.

“Do not apply when temperature exceeds 90°F.” “Do not broadcast apply this product when air temperatures are above 90°F (85°F for St. Augustinegrass) unless temporary turf injury can be tolerated.”

Every year we’ll see lawns that are injured or killed because of lawn herbicides being applied when temperatures are too hot.

Summer is usually a rainy and windy time of the year. Many lawn herbicide labels include statements such as the following.

“Allow 12 hours after application before watering lawn for maximum effectives on listed weeds.” “Apply only when wind is no more than 10 mph.” “Applying this product in calm weather when rain is not predicted for the next 24 hours will help to ensure that wind or rain does not blow or wash pesticide off the treatment area.”

It is critical to read and follow the label directions and precautions for any pesticide you use. Pesticide labels, including herbicides, include the following statements.

“To the extent consistent with applicable law, the buyer assumes all risks of use, storage, or handling of this product not in accordance with label directions.” “It is a violation of Federal law to use this product in a manner inconsistent with its labeling.”

Crabgrass plant growing in centipedegrass lawn

Crabgrass growing in centipedegrass lawn. Photo credit: UF/IFAS Extension

By the time summer arrives, many of the lawn weeds are mature, which means they are well established with extensive root systems. These mature, well established weeds are much more difficult to control. They are more susceptible to herbicides when they are small, young, and not well established. Also, these mature weeds have been allowed to produce countless numbers of seeds as they move into summer. Most weeds are prolific seed producers. For example, a single crabgrass plant (a common summer lawn weed) can produce 150,000 seeds.

Applying a preemergence lawn herbicide in February to help prevent summer annual weeds such as crabgrass or applying a postemergence lawn herbicide during spring while the weather is mild and before the weeds are out of control simply makes more sense than waiting until summer.

The best options now with lawn weed control involve continuing to follow good mowing practices, maybe hand removal of some weeds, and just simply waiting it out until next February and spring to worry with the use of lawn herbicides.

In the meantime, you may want to read the following UF/IFAS Extension publication on lawn weed control.

https://edis.ifas.ufl.edu/pdf/EP/EP14100.pdf

Larry Williams, UF/IFAS

Centipedegrass Weed Control:  You Only Need 3 Herbicides!

Centipedegrass Weed Control: You Only Need 3 Herbicides!

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 in flower

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!

 

Controlling Torpedograss

Controlling Torpedograss

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!

 

Soil Compaction in the Landscape

Soil Compaction in the Landscape

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!

 

How to Control Doveweed, the Late-Summer Lawn Menace

How to Control Doveweed, the Late-Summer Lawn Menace

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!

 

Reducing Your Lawn Size Options

Reducing Your Lawn Size Options

Photo Courtesy:  Stephen Greer

Lawn areas come in all sizes and shapes.  Some are large open expanses providing long views and others are smaller versions surrounded by shrubs and trees creating a more private and secluded setting.  There are a number of reasons for reducing the size of a lawn with some coming into play with your decisions.  A home lawn is often an important part of the landscape that provides a place to play outdoors from picnicking, tossing the ball to taking a quite stroll.

Maintaining a healthy lawn is important to an overall performance of this part of the landscape.  Several factors are involved in the success in keeping a strong and resilient lawn.  Understanding the needs of a grass to remain healthy involve soil testing to address soil pH and nutrient needs plus water challenges.  Misuse of fertilizer and over irrigation can be costly to you and to the overall health of the lawn. These decisions can lead to reducing lawn size to managing cost or removing underused areas.

There are big benefits to reducing your lawn from saving time in mowing, trimming and other manicuring needs to saving energy costs involving the lawn mower not to mention reducing pollution from the mower or weed eater.  The reduced amounts of pesticides needed to manage weeds and disease to the lawn saves time and money.

Another way to look at the reducing the size of our lawn is there will be more space for expanding plant beds and potential tree placement.  These settings increase the opportunities for a more biodiverse landscape providing shelter, protection and food options for birds and other wildlife.

Photo Courtesy:  Stephen Greer

The lawn can serve as a transition space that leads from one garden room space to another, while still offering a location to bring the lawn chair out to enjoy all that is around your lawn.  Lawns and the landscape are ever changing spaces, especially as your trees and shrubs grow and mature to sizes that can directly impact the lawn performance.  Often levels of shade will diminish edges and other areas of the lawn.  This often will define the reduction of the lawn size moving going forward.  Just remember that lawns and landscapes occupy a three-dimensional space involving the horizontal, vertical and overhead spaces.  Just look around and think about what is best for you, your family and the setting.Are you more interested in developing other parts of the landscape?  With many of us spending more time at home over the last year plus it gave time to think about the outdoor areas.  Growing our own vegetables may be a new or expanding part of the landscape with the use of raised beds or interplanting into the existing landscape.   Gardening can assist in reducing stress while at the same time providing that fresh tomato, lettuce, herbs and other fun healthy produce.

What ever your decisions are enjoy the lawn and landscape.  For additional information, contact your local University of Florida IFAS Extension office located in your county.