Lawns and Turf

What is this winter weed that shows up every year at this time?

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Florida betony plant
Figure 1 – Flower and foliage of Florida betony.

This weed is Florida betony. It is also called rattlesnake weed.

The publication Controlling Florida Betony in the Landscape gives cultural and chemical controls for this weed in lawns and landscape beds. The authors are Mark Czarnota, Ph.D., and Tim Murphy, Ph.D., Weed Control Specialists. Departments of Horticulture and Crop Science

Click here to see the publication for the following information:

Florida betony (Stachys floridana) (also called rattlesnake weed and hedge nettle) is a problem weed in both turfgrasses and ornamentals.

Florida betony tubers
Figure 2 – Tubers of Florida betony that look like the rattle of a rattlesnake, hence the name “rattlesnake weed.”

Florida betony is a “winter” perennial and, like most plants in the mint (Labiatae) family, has a square stem with opposite leaves. Flowers are usually pink and have the classic mint-like structure (Figure 1). Unlike its relatives, it has the unique characteristic of producing tubers that look like the rattles (buttons) of a rattlesnake, hence the name “rattlesnake weed” (Figure 2).

Click here to readthepublicationn Controlling Florida Betony in the Landscape

What are the best post-emergence herbicides for annual bluegrass control in turf?

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Annual bluegrass - Robert Vidéki, Doronicum Kft., Bugwood.org
Annual bluegrass – Robert Vidéki, Doronicum Kft., Bugwood.org

Postemergence Annual Bluegrass Control in Turf

Patrick McCullough, Extension Weed Specialist, University of Georgia

Edited from a more complete article which can be found here.

Contrary to its name, both annual (live for one season) and perennial (live for many seasons) populations of annual bluegrass may be found in turf.  Annual bluegrass may out-compete other turf species during late fall and early spring.  Annual bluegrass often dies from summer stresses but may survive if irrigated – especially the perennial biotypes

Postemergence Control (See Table 3)

Annual bluegrass may be selectively controlled with postemergence herbicides (Table 3).

Landscapers managing warm-season grasses have more options for selective postemergence annual bluegrass control than cool-season grasses.

Flazasulfuron (Katana), foramsulfuron (Revolver, Tribute Total), rimsulfuron (TranXit), and trifloxysufluron (Monument) are labeled for bermudagrass and zoyiagrass non-residential commercial lawns and other sites.  Flazasulfuron and rimsulfuron are also labeled for use in centipedegrass. Efficacy of these herbicides generally increases under warm temperatures in spring compared to winter and non-ionic surfactants may enhance efficacy.

Pronamide (Kerb) is a restricted use herbicide for annual bluegrass control in non-residential bermudagrass, centipedegrass, St. Augustinegrass, seashore paspalum, and zoysiagrass.  Pronamide is root-absorbed and must be watered in following applications.  Pronamide efficacy is generally slower than most sulfonylureas and activity for annual bluegrass control may take approximately four to six weeks.

Atrazine (Aatrex, Bonus S, others) and simazine (Princep, WynStar, others) may also be applied to bermudagrass, centipedegrass, St. Augustinegrass, and zoysiagrass for selective postemergence annual bluegrass control.  These herbicides often provide erratic control of annual bluegrass but may control other grassy and broadleaf weeds.  Actively-growing bermudagrass is sensitive to atrazine and applications are recommended only during the late fall and winter months.

Dormant bermudagrass may be treated with nonselective herbicides, such as glyphosate (Roundup, Touchdown, others), glufosinate (Finale), and diquat (Reward).  These herbicides will injure or kill existing vegetation, including annual bluegrass and managers should only spray at peak dormancy when no green turfgrass foliage is observable.  Nonselective herbicides should only be applied to completely dormant bermudagrass and applications during early spring may delay greenup with significant turf injury.

Flumioxazin (Sureguard) is a new herbicide for pre- and postemergence annual bluegrass control but applications are limited to dormant bermudagrass only.  Flumioxazin use after greenup or on other species are not recommended due to excessive injury potential.

Selective annual bluegrass control options in cool-season lawns are limited.

Ethofumesate (Prograss) controls established annual bluegrass in perennial ryegrass, tall fescue and dormant bermudagrass (see the current edition of the Georgia Pest Management Handbook). Two or three ethofumesate applications may be applied in late fall at three- to four-week intervals. Annual bluegrass control may be seen that fall, but control is usually observed the following spring. Annual bluegrass control with ethofumesate may vary greatly over years depending on environmental conditions.

Amicarbazone (Xonerate) is a new Photosystem II inhibitor, similar to triazine herbicides, but may be used in tall fescue lawns and other cool-season grasses.  Applications of amicarbazone in Georgia are limited to springtime only to minimize injury to cool-season grasses.  Warm-season turf is very tolerant to amicarbazone and may be treated at any seasonal timing.

Bispyribac-sodium (Velocity) has shown potential for selective annual bluegrass control in tall fescue and perennial ryegrass lawns.  However, this herbicide is currently registered for creeping bentgrass and perennial ryegrass on golf courses and sod farms only.  Spot treatments of nonselective herbicides are generally the most effective treatment regimen for annual bluegrass control in cool-season grasses.

Table 3.  Efficacy of postemergence herbicides for annual bluegrass control in turfgrass.

Common Name Trade Name (Examples) Efficacy
amicarbazone Xonerate F-G
atrazine Aatrex, others E
bispyribac-sodium Velocity F-G
flazasulfuron Katana G-E
flumioxazin Sureguard F-G
foramsulfuron Revolver E
glufosinate Finale E
glyphosate Roundup, others E
imazaquin Image P-F
metribuzin Sencor G
pronamide Kerb E
rimsulfuron Tranxit E
simazine Princep, others G-E
thiencarbazone + foramsulfuron + halosulfuron Tribute Total G-E
trifloxysulfuron Monument E

E = Excellent (90 to 100%), G = Good (80 to 89%), F = Fair (70 to 79%), P = Poor (<70%).

For more information

Annual Bluegrass Control in Residential Turfgrass

Annual Bluegrass Control in Non-Residential Commercial Turfgrass

What are the best methods to prevent annual bluegrass in turf?

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Pre-emergence Annual Bluegrass Control in Turf

Patrick McCullough, Extension Weed Specialist, University of Georgia

Edited from a more complete article which can be found here.

Annual bluegrass (Poa annua L.) is a problem winter annual weed.  Contrary to its name, both annual (live for one season) and perennial (live for many seasons) populations of annual bluegrass may be found in turf.

Annual bluegrass seed germinates in late summer/early fall once soil temperatures fall below 70° F.  Annual bluegrass may out-compete other turf species during late fall and early spring.  Annual bluegrass often dies from summer stresses but may survive if irrigated – especially the perennial biotypes.

Cultural Control of Annual Bluegrass

Irrigate deeply and infrequently to encourage turfgrass root development and improve the ability of turf to compete with annual bluegrass.  Overwatering, especially in shady areas, may encourage annual bluegrass invasion.

Avoid soil compaction.  Core aerate during active turf growth to encourage quick recovery.  For cool-season grasses, time aerfications before annual bluegrass germinates.

Reduce nitrogen fertilization during peak annual bluegrass germination and periods of vigorous growth.  Fertilizing dormant turfgrasses when annual bluegrass is actively growing may make infestations worse.

Use the proper mowing height, frequency, and equipment for your turfgrass (Table 1).  Raise the turf mowing height during peak annual bluegrass germination.

Mow turfgrass frequently during periods of vigorous growth to prevent scalping.  Returning clippings recycles nutrients to the soil but clippings may need to be removed when annual bluegrass is producing seedheads to reduce the spread of viable seed.

Prevention Using Pre-emergence Herbicides (See Table 2)

Preemergence herbicides may prevent annual bluegrass establishment from seed.  However, preemergence herbicides will not eradicate established plants and will not effectively control perennial biotypes of annual bluegrass from spreading vegetatively.  Application timing of preemergence herbicides for annual bluegrass control is very important.  Herbicides must be applied in late summer/early fall before annual bluegrass germination.  A second application can be applied in winter to control later germinating plants.  Fall applied preemergence herbicides should not be used if reseeding or resodding is needed to repair areas of damaged turf within several months after herbicide applications.

Several preemergence herbicides used for summer annual weed control will effectively control annual bluegrass in fall and winter (Table 2).  Fall applications of herbicides such as bensulide (Betasan), dithiopyr (Dimension), flumioxazin (Sureguard), oxadiazon (Ronstar, Starfighter), pendimethalin (Pendulum, others), and prodiamine (Barricade, others) may effectively control annual bluegrass.  Indaziflam (Specticle) provides excellent preemergence control of annual bluegrass and also provides early-postemergence control as well.  Indaziflam is only labeled in warm-season turfgrasses but may provide greater application timing flexibility than dinitroaniline herbicides in fall.

Combination herbicide products are also available which may improve efficacy of applications.  These products include oxadiazon plus bensulide (Anderson’s Crab and Goose), oxadiazon plus prodiamine (Regalstar), and benefin plus oryzalin (Team 2G or Team Pro).  Many preemergence herbicides are available under a wide variety of trade names and formulations and turf mangers should carefully read label directions before applications.

Atrazine (Aatrex, Purge, others) and simazine (Princep, WynStar, others) are labeled for centipedegrass, zoysiagrass, St. Augustinegrass and bermudagrass.  Atrazine can be applied to actively growing and dormant centipedegrass or St. Augustinegrass but bermudagrass can be injured if treated while actively growing.  Both herbicides have excellent preemergence activity on annual bluegrass but soil residual is generally shorter (four to six weeks) compared to aforementioned herbicides.  Several atrazine products are restricted use pesticides and turf managers should check labels for further information before use.

Mesotrione (Tenacity) is labeled for use in centipedegrass, perennial ryegrass, St. Augustinegrass (sod production only), tall fescue, and dormant bermudagrass (Table 2).  Mesotrione may be applied during establishment of these grasses (except bermudagrass) and effectively controls annual broadleaf and grassy weeds.  Preemergence applications of mesotrione control or suppress annual bluegrass but postemergence use is ineffective for control of established plants.  Mesotrione may be applied in tank-mixtures with atrazine or simazine on centipedegrass to improve efficacy of applications.

Most preemergence herbicides will provide similar initial efficacy if applied before annual bluegrass germination and sufficient rain or irrigation is received.  Preemergence herbicides require incorporation from irrigation or rainfall so that weeds may absorb the applied material.  In order to effectively control annual bluegrass, preemergence herbicides must be concentrated in the soil seedbank.  Retention on leaf tissue can be avoided by irrigating turf immediately after application for effective soil incorporation and herbicide activation.

Preemergence herbicide applications on non-irrigated sites have less potential for residual control, compared to irrigated turf, from product loss, poor soil incorporation, and failure to activate the herbicide.  Practitioners should return clippings on non-irrigated sites to help move potential herbicides remaining on leaf tissue to the soil.  If clippings are collected as part of routine maintenance, practitioners should consider returning clippings until at least half to one inch of rainfall is received.  Granular products may also be applied to non-irrigated sites for better soil incorporation than liquid formulations.  Granular products may be easier to handle and apply with less equipment necessary than sprayable formulations.  Granular herbicides should be applied when morning dew is no longer present to avoid interference from leaf tissue.

Managing Herbicide Resistance

Repeated use of one herbicide chemistry may control annual bluegrass but resistance may develop.  Herbicide resistance is the survival of a segment of the population of weeds following a herbicide dosage lethal to the normal population.  Resistance occurs from repeated use of the same herbicide or mode of action over years and may be a concern with annual bluegrass.

Triazine herbicides, atrazine and simazine, have been repeatedly used for years due to the wide spectrum of weeds controlled as pre- or postemergence treatments in warm-season grasses.  Resistance in weed populations has been reported with these herbicides which may contribute to inconsistent efficacy for annual bluegrass control in turf.  Resistance to sulfonylureas has been reported in numerous weed species and repeated use in turfgrasses may also contribute to resistance in annual bluegrass populations.

Preemergence chemistries, such as the dinitroanalines, (benefin, oryzalin, pendamethalin and prodiamine) may have resistance among weed populations from repeated use over years.  Turf managers should rotate preemergence herbicides from dinitroanilines to other modes of action to minimize resistance in annual bluegrass populations.  Herbicides to consider in rotation programs from dinitroanilines would include indaziflam, ethofumesate, or oxadiazon.  These chemistries offer a different mode of action than dinitroanilines but cost, label restrictions, and turfgrass tolerance may be limiting factors for using these products.  Combination herbicides are also available, such as oxadiazon + prodiamine (Regalstar) and oxadiazon + bensulide (Anderson’s Crab and Goose), with more than one mode of action that effectively control annual bluegrass in turf.

Table 1.  Mowing requirements for commercial turfgrasses.

Mowing Requirements for Turfgrasses
Species Mower Type Height (inches) Frequency (days)
Bermudagrass
    Common Rotary/reel 1 to 2 5 to 7
    Hybrid Rotary/reel 0.5 to 1.5 3 to 4
Centipedegrass Rotary 1 to 2 5 to 10
Perennial Ryegrass Rotary/reel 0.5 to 2 3 to 7
St. Augustinegrass Rotary 2 to 3 5 to 7
Tall Fescue Rotary 3 5 to 7
Zoysiagrass Reel 0.5 to 2 3 to 7

 

Table 2.  Efficacy of preemergence herbicides for annual bluegrass control in commercial turfgrasses.

Common Name Trade Name (Examples) Efficacy
atrazine Aatrex, various E
benefin Balan, others E
bensulide Betasan, others F
dithiopyr Dimension G
ethofumesate Prograss G-E
flumioxazin Sureguard G
indaziflam Specticle E
mesotrione Tenacity F
oryzalin Surflan, others G
oxadiazon Ronstar, others G
pendimethalin Pendulum, others G
prodiamine Barricade, others E
pronamide Kerb E
simazine Princep, others E

E = Excellent (90 to 100%), G = Good (80 to 89%), F = Fair (70 to 79%), P = Poor (<70%).

For more information

Annual Bluegrass Control in Residential Turfgrass

Annual Bluegrass Control in Non-Residential Commercial Turfgrass

Identification and Control of Spring Dead Spot

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Alfredo Martinez, Turfgrass Pathologist, J.B. Workman, Graduate Assistant, Crop and Soil Sciences Department and Clint Waltz, Turfgrass Specialist

This Alert is an excerpt from the publication Identification and Control of Spring Dead Spot 

Spring dead spot Martinez
Figure 1 Multiple circular patches of dead, bleached grass are evident in the spring.

Spring dead spot (SDS) is a persistent and destructive disease of bermudagrass in Georgia. The disease is particularly prevalent and damaging in north Georgia, especially in the Piedmont region. However, SDS can be observed throughout the state after harsh winters and in areas where bermudagrass has been exposed to freezing temperatures for extended periods of time. The disease has also been observed in zoysiagrass, although less frequently.

Figure 2 Sharp edges between dead and healthy grass are observed once turfgrass greens up in spring.
Figure 2 Sharp edges between dead and healthy grass are observed once turfgrass greens up in spring.

Symptoms

As turfgrass “greens up,” well-defined circular patches of dead, bleached-out grass are noticeable in affected areas (Figure 1). Non-infected bermudagrass resumes growth, accentuating the infected areas. Sharp edges between dead and healthy grass are observed once turfgrass greens up in spring. (Figure 2).

Roots, rhizomes and stolons are sparse and dark-colored (necrotic) (Figure 3). Leaves become bleached, gray and straw-colored. Recovery from the disease is slow. Because the turfgrass in affected patches is dead, the primary means of recovery occurs by spread of stolons into the patch. Because recovery is dependent on lateral infill of surrounding bermudagrass, symptoms can remain visible well into the

growing season. If not managed properly, these patches may reappear in the same location the following spring along with weed species that may invade the voids. Patches can get larger year after year.

Disease cycle

The fungi casuing the disease are active in the fall and spring when cool, moist conditions exist. They do not kill bermudagrass directly; instead, they make turfgrass more susceptible to cold and freezing injury by feeding on roots, rhizomes and stolons.

Spread of these fungi primarily occurs through movement of infected plants or infested soil by equipment, people, animals and running water.

Infection of the turfgrass begins when soil temperatures are less than 70 °F. Typically, in Georgia, infection of susceptible grasses begins in late September or early October and will continue as long as soil temperatures are above 50° F. Fungal growth and plant infection can resume at these temperatures in early spring, coinciding with bermudagrass transitioning from winter dormancy (also referred to as “green up”).

Disease Control

Complete control of SDS in a single growing season is uncommon. It typically takes two to four years of proper cultural management and fungicide applications before acceptable control can be achieved. This has led to SDS becoming one of the more difficult diseases for growers to manage on an annual basis.

Resistant cultivars

The primary cultivars grown and used in Georgia (e.g., Tifway, TifSport, Tifton 10, Celebration, etc.) have shown susceptibility to SDS. However, SDS tolerance has been enhanced through breeding. Most “tolerant” cultivars (e.g., Patriot) may still get the disease but not as severely. In general, cultivars with more cold tolerance have less SDS than non-cold tolerant bermudagrasses. On sites where SDS has been a chronic problem, conversion to a tolerant cultivar is an option for disease management.

Cultural practices

Cultural practices that improve the cold-hardiness of bermudagrass can be particularly effective for managing SDS.

Since high nitrogen levels can reduce the winter hardiness of bermudagrass, apply no more than ½ pound of nitrogen per 1,000 ft2 be after mid-September.

Potassium applications in the fall (September or October) that total 1 pound of K2O per 1,000 ft2 can be helpful in improving the winter hardiness of bermudagrass and thus reduce SDS severity. Potassium applications should be applied based on soil test results.

A neutral to slightly alkaline soil pH can increase SDS severity. Maintain soil pH at 5.8 to 6.2. Use acid-forming fertilizers on sites with near neutral to alkaline pH. Apply iron, manganese and other micronutrients based on soil test results.

Any soil condition that reduces bermudagrass root growth such as compaction, excessive thatch (> ½ in) and poor drainage can also increase the severity of SDS. Core aeration and other practices that reduce soil compaction and encourage the production of new roots can be helpful in managing this disease.

Chemical Control

Timing, selection and application of fungicides are important for preventative management of SDS. Research has shown that one application of fungicide in the fall when soil temperatures are between 60° and 80° F provides the best control of SDS. When disease pressure is high, growers may want to make two applications. If a second application is necessary, it should be made four to six weeks after the first application when soil temperatures remain between 60° and 80° F. For complete meteorological information, see GeorgiaWeather.net . For improved results, it is recommended that fungicides be applied at high spray volumes (> 5.0 gal / 1,000 ft2) and/or immediately watered-in.

There have been mixed results from turfgrass managers around the state regarding chemical control of SDS. Those who have seen good results say they spray preventative fungicides that target SDS each year and have been doing so for several years. Therefore, it is important to keep in mind that controlling SDS takes time and control usually cannot be obtained in a single season.

A complete list of fungicides, formulations and product updates for SDS can be found in the annual Georgia Pest Management Handbook  and the Turfgrass Pest Control Recommendations for Professionals . Some fungicide options are exclusively for golf course settings. Always check fungicide labels for specific instructions, restrictions, special rates, recommendations, follow-up applications and proper handling.

This article is an excerpt from a more complete publication which can be found here.

What causes these irregular or circular patches in lawns?

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Control Take-All Root Rot this Fall!

Alfredo Martinez, UGA Plant Pathologist and Willie Chance, UGA Center for Urban Agriculture

Take-all root rot -Clarissa Balibalian, Mississippi State Univ, Bugwood.org
Take-all root rot -Clarissa Balibalian, Mississippi State Univ, Bugwood.org

This year did your lawns show round or irregular dead or dying patches? Did the grass yellow or wilt even though the soil is moist? If so, these lawns may be infected with Take All root rot. This fungal disease affects cen­tipede, St. Augustine and Bermuda lawns

The fungus causing Take-All rots the lawn’s roots and aboveground runners (stolons).

To identify the disease look for:

  • Black, rotted roots.
  • Yellowed or dying areas of turf.
  • Stolons that are brown or black at the nodes or have dead patches.
  • One of the best ways to identify Take All is to look for the black, thread-like hyphae growing on the undersides of the stolons. You will need a micro­scope or a good hand lens to see these. Many UGA Extension County Offices have resources agents use to diag­nose diseases like this. Find your local UGA Extension office here.

This fungus prefers cooler weather – infecting lawns in the fall, growing through the winter and slowing growth in late spring. Much damage from this disease is done in the fall and spring. By the time we see disease symptoms (often in early spring and summer), the harm is done. Damage can be mistaken for green up problems. Expect the disease to be less active as temperatures increase.

Since this disease destroys roots, lawns may be slow to recover. Affected lawns are more susceptible to other stresses, like her­bicides and drought. Turf may not show evidence of the disease on the leaves until turf is stressed. For instance, a lawn with an unnoticed case of Take-All may be damaged or killed by the stress of a normal herbicide application. This can reflect poorly on the pesticide applicator.

Fall is the best time to control this disease. The best control is to improve cultural prac­tices to prevent the disease and to increase the vigor of the grass so that it will recover quickly. To slow disease progress:

  • Make sure the soil pH is not too high (Disease is less active below a pH of 6.5).
  • Water deeply and infrequently. Do not allow the soil to remain wet.
  • Remove thatch if the layer is thicker than one-half inch.
  • Mow at the proper height for your turfgrass.
  • Use fertilizers containing equal amounts of nitrogen and potassium.
  • Do not apply high amounts of nitrogen fertilizers in the fall. Typically warm season turf fertilization is completed by September 15.

Apply fungicides in September and again in October for best disease prevention. In warmer months, a fungicide may help, especially if sodding or plugging turf into affected areas. However, fall applications are best at controlling this disease. Fall applications should prevent the need for spring applications and should reduce Take-All damage in affected lawns and improve spring turf vigor.

For pesticide recommendations see the UGA publications –  Pest Management Handbook or Turfgrass Pest Control Recommendations for Professionals

For more information on controlling Take All see Turfgrass Diseases in Georgia or Enfermedades de los céspedes en Georgia

Fall Management of Large Patch Disease in Turfgrass

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Large patch disease - Alfredo Martinez, UGA
Large patch disease – Alfredo Martinez, UGA

Alfredo Martinez, Extension Plant Pathologist

Large patch disease of turfgrass is most common in the fall and in the spring as warm season grasses are entering or leaving dormancy. Large patch is caused by the fungus Rhizoctonia solani. It can affect zoysia grass, centipedegrass, St. Augustinegrass and occasionally bermudagrass.

Symptoms of this lawn disease include irregularly-shaped weak or dead patches that are from 2 feet to up to 10 feet in diameter. Inside the patch, you can easily see brown sunken areas. On the edge of the patch, a bright yellow to orange halo is frequently associated with recently affected leaves and crowns. The fungus attacks the leaf sheaths near the thatch layer of the turfgrass.

Large patch disease is favored by:

  • Thick thatch
  • Excess soil moisture and poor drainage
  • Too much shade which stresses turfgrass and increases moisture on turfgrass leaves and soil
  • Early spring and late fall fertilization.

If large patch was diagnosed earlier, fall is the time to control it with fungicides. Consult the Pest Management Handbook , Turfgrass Pest Control Recommendations for Professionals  or your local Extension Office for fungicide recommendations. Fall fungicide applications may make treating in the spring unnecessary. Always follow label instructions, recommendations, restrictions and proper handling when applying pesticides.

Cultural practices are very important in control. Without improving cultural practices, you may not achieve long term control.

  • Use low to moderate amounts of nitrogen, moderate amounts of phosphorous and moderate to high amounts of potash. Avoid applying nitrogen when the disease is active.
  • Avoid applying N fertilizer before May in Georgia. Early nitrogen applications (March-April) can encourage large patch.
  • Water timely and deeply (after midnight and before 10 AM). Avoid frequent light irrigation. Allow time during the day for the turf to dry before watering again.
  • Prune, thin or remove shrub and tree barriers that contribute to shade and poor air circulation. These can contribute to disease.
  • Reduce thatch if it is more than 1 inch thick.
  • Increase the height of cut.
  • Improve the soil drainage of the turf.
  • Apply lime if soil pH is acidic (i.e. less than 6.0 – except on centipede lawns). Soil pH of more than 6.5 can encourage take all infections.

See the current Georgia Pest Management Handbook for more information. Check fungicide labels for specific instructions, restrictions, special rates, recommendations and proper follow up and handling.

Additional resources:

Turfgrass Diseases in Georgia or Enfermedades de los céspedes en Georgia

Turfgrass Diseases: Quick Reference Guide or Enfermedades de Cespedes Guia de Referencia Rapida

UGA Pest Management Handbook

Turfgrass Pest Control Recommendations for Professionals

When is the best time of year to control fire ants?

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Fall is the best time to control fire ants!

Original story by Sarah Lewis, student writer with the UGA College of Agricultural and Environmental Sciences

“April and September are good times to apply baits, once at the start of the season and toward the end to help control before they come back in the spring,” said Will Hudson, a professor with the UGA College of Agricultural and Environmental Sciences.

Fire ants are most active in warm weather. Fire ant season can last 10 to 11 months out of the year in the most southern areas of Georgia. Controlling ant colonies before they produce a mound is important. However, Hudson says that once a treatment program is in effect, timing is not all that important.

Baits and sprays

The general rule of thumb is if the area is one acre or less, don’t use baits. Re-infestation is more likely from colonies outside of the yard when baits are used.

One important thing to remember is the difference between ‘no mounds’ and ‘no ants.’ “There is a difference between eliminating ants and controlling them,” he said. “Baits do not eliminate ants because there is no residual control. A new colony can still come in and be unaffected by the bait laid down prior to their arrival.”

To eliminate mounds completely, apply baits every six months, Hudson said. “There will be invasion in the meantime, and you will still have fire ants, just not enough to create a new mound,” he said.

Hudson recommends treating lawns smaller than an acre with a registered insecticide in a liquid solution. This should rid the lawn of fire ants for one to three months. If you choose a granular product, measure carefully to be sure you apply the correct amount of material and get good, even coverage, he said.

The least effective treatment option for most people is individual mound treatments, according to Hudson. Treating mounds in general is going to be an exercise of frustration, and killing an entire colony by treating just the mound is a challenge, he said.

Minimal impact

Baits are considered to have minimal environmental effects for those who chose not to use hazardous chemicals. Once the bait is out, there is hardly anytime for anything to come in contact with it before the ants get to it.

Nonchemical options include using steam or boiling water. “We recommend using boiling water to treat a mound near an area such as a well where you do not want any chemicals,” Hudson said. “Using hot water is very effective, but the problem is you are not always able to boil the water right next to the area you want treated.” Carrying the boiling water can inflict serious burns, so extreme caution should be used when treating with this method.

There are products on the market that are approved by the Environmental Protection Agency and labeled as organic. Hudson says organic designation is a “slippery” definition. There is an official USDA certification and many states have their own set of regulations when labeling a product as organic. This labeling can mean the product is either a natural product or derived from a natural product. “While there are a few products that qualify as organic, with most baits the actual amount of pesticide applied is minimal,” he said.

Realistic expectations

Hudson says to be careful when choosing a product because the labels can be confusing, even deceptive, and it is difficult to make the right choice. For assistance in selecting a product, contact your local UGA Cooperative Extension agent.

“The most important thing to remember is that you need to be realistic in your expectations,” Hudson said. “If you are treating mounds, you need to be prepared. You are going to chase the mounds around the yard.”

For more information on selecting a control measure:

Find pesticide recommendations in the UGA Pest Management Handbook

Fire Ant Control Materials

Managing Imported Fire Ants in Urban Areas

Fall is the best time to treat for fire ants

 

Post-emergence control of sedges in turf

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Information supplied by Patrick McCullough, UGA Extension Weed Scientist and the publication Weed Control in Home Lawns

Purple nutsedge Forest and Kim Starr, Starr Environmental
Purple nutsedge – Forest and Kim Starr, Starr Environmental, Bugwood.org

Hot and humid weather contributes to certain weeds in lawns – particularly sedges! Sedges come in many types – nutsedges, annual and perennial sedges and kyllinga. Identification of the sedge is the first step (though exact id of sedges can be difficult!) See this site if you need help with identification. Another great resource for weed identification is the UGA publication Weeds of Southern Turf.

Once you identify the sedge; select control methods based on this identification and the weeds biology – annual/perennial, warm/cool season, etc.

Post-emergence herbicide controls for sedges

  1. Leaf tips of Yellow and Purple Nutsedge. Notice the differences in leaf tips. Purple Nutsedge has a keel shape, and yellow nutsedge is pinched. Mark Czarnota
    Leaf tips of Yellow and Purple Nutsedge. Notice the differences in leaf tips. Purple Nutsedge has a keel shape, and yellow nutsedge is pinched. Mark Czarnota

    flazasulfuron – Katana (25 WG) is a selective herbicide for control of annual and perennial grasses, sedges and broadleaf weeds in bermudagrass, zoysiagrass and certain other warm season grasses. Flazasulfuron has postemergence and some preemergence activity and may be used on golf courses (fairways, roughs and tees) and the following non-residential turf areas: industrial parks, tank farms, sod farms, seed farms, cemeteries, professionally managed college and professional sport fields and commercial lawns for control of cool season grasses and weeds from tolerant grasses. The maximum yearly application rate is 9.0 oz. per acres. Use only on labeled turfgrasses or severe injury may result. Do not apply to newly seeded, sodded or sprigged turfgrass until well established. Allow at least 2 weeks from the last application to the time of overseeding when applied at 1.5 oz per acre. Allow 4 weeks for rates above 1.5 oz

  2. halosulfuron – Sedgehammer (75DF) is a selective herbicide for postemergence control of sedges such as purple and yellow nutsedge in established lawns. Sedgehammer may be applied to most major warm- and cool-season turfgrasses. For best results, apply 2/3 to 1 1/3 ounces of product per acre after nutsedge has reached the three to eight leaf stage of growth. A second treatment may be required six to 10 weeks after the initial treatment. Use the lower rate in light infestations and the higher rate in heavy infestations. No more than four applications can be made with the total use rate not exceeding 5 1/3 ounces of product per acre per season. Use 0.25% v/v of a nonionic surfactant (1 quart per 100 gallons of spray solution) for broadcast applications. Use only high quality nonionic surfactants that contain at least 80% active ingredient.
  3. imazaquin – Image (1.5 lbs/gallon) is labeled for use only in established bermudagrass, centipedegrass, St. Augustinegrass and zoysiagrass. All other turfgrasses can be severely injured by imazaquin. This herbicide is primarily used for the postemergence control of annual sedges, yellow nutsedge, purple nutsedge and wild garlic. Imazaquin will also control numerous winter annual weeds and sandbur.
  4. Green kyllinga - Rebekah D. Wallace, University of Georgia, Bugwood.org
    Green kyllinga – Rebekah D. Wallace, University of Georgia, Bugwood.org

    sulfentrazone — Dismiss (4 lbs/gallon) is a postemergence herbicide labeled for most major warm- and cool-season turfgrasses. Use lower rates on cool-season turfgrass than warm-season turf due to injury concerns. Dismiss controls annual and perennial sedges, broadleaf weeds and suppresses goosegrass.Dismiss may be used on seeded, sodded or sprigged turfgrasses that are well established. Applications of Dismiss can be initiated following the second mowing provided the turfgrass has developed into a uniform stand with a good root system. Turfgrass injury could result from application of this product on turfgrass that is not well established or has been weakened by stresses such as unfavorable weather conditions, disease, chemical or mechanical damage. Dismiss may cause temporary discoloration to St. Augustinegrass and zoysiagrass.

  5. Sulfentrazone is also found in the combination products Surge and Q4. Surge contains sulfentrazone, 2,4-D, dicamba and MCPP and effectively controls annual, biennial and perennial broadleaf weeds. Surge may be applied to dormant bermudagrass, zoysiagrass and bahiagrass but do not apply during spring green-up or in the fall during the transition period between active growth and dormancy. Q4 contains sulfenetrazone, quinclorac, 2,4-D and dicamba for broadleaf weed, crabgrass and nutsedge control. For best results, add 0.25 lb of active ingredient per acre of quinclorac (Drive) and 0.06 to 0.19 lb of active ingredient per acre of sulfentrazone (Dismiss) for crabgrass and nutsedge control, respectively.
  6. sulfosulfuron — Certainty (75DF) is labeled for bermudagrass, St. Augustinegrass, zoysiagrass and centipedegrass. Certainty selectively controls sedges, kyllingas and tall fescue. A second application of 0.75 to 1.25 ounces per acre may be made four to 10 weeks after initial treatment, if needed. Some chlorosis or stunting of the desirable turf may occur following application. Use of a nonionic surfactant is required. Certainty suppresses annual bluegrass and controls or suppresses roughstalk bluegrass.
  7. trifloxysulfuron-sodium – Monument (75 DG) is labeled for established bermudagrass and zoysiagrass. Monument is not recommended for use on other turfgrass species. Controls nutsedge(s), green kyllinga, annual bluegrass, tall fescue, torpedograss and certain broadleaf weeds. Not labeled for use on home lawns. Add a nonionic surfactant at 0.25 to 0.5% v/v to the spray mix. Avoid mowing for 1 to 2 days before and after application. For nutsedge repeat the application at 4 to 6 weeks if regrowth is observed. DO NOT overseed bermudagrass with cool-season turfgrasses for 3 weeks after application.

Cultural practices to control sedges

The first line of defense against weeds is to follow cultural practices that promote vigorous turfgrass growth and development. Weeds do not easily invade turfgrasses that are properly fertilized and watered and that are mowed at the correct height and frequency. Weeds appear primarily in bare or thin areas of the turfgrass, which may be due in part to one or more of the following:

  • Use of non-adapted turfgrasses.
  • Improper fertilization (too much or too little, wrong application date or N-P-K ratio).
  • Improper watering (too much or too little).
  • Improper mowing procedures (cutting height is too low or too high, or the turfgrass is not mowed at correct time intervals).
  • Failure to control diseases and insects.
  • Excessive amounts of thatch.

Visit www.GeorgiaTurf.com for additional information on turfgrass maintenance practices. The impact of proper cultural practices on a lawn weed control program cannot be overemphasized. Properly maintained turfgrasses are more competitive with weeds than turfgrasses that do not receive good cultural practices. The use of herbicides without following approved cultural practices will not result in a high quality, weed-free lawn.

Read the entire publication from which most of this information comes Weed Control in Home Lawns

Fall Armyworms in Turf

by

Will Hudson1, Cheri Abraham2 and Kris Braman1

1 UGA Entomologists and 2 Field Operations Manager/ Entomologist at US Citrus, LLC

Fall Armyworms in Turf
Large armyworm. Photo by Kris Braman, UGA Entomologist

In late summer, almost every year, caterpillars invade turfgrass throughout Georgia. The damage to established turf is mostly aesthetic, but newly sodded or sprigged areas can be more severely damaged or even killed. While there are several caterpillars that can damage turfgrass, in late summer most of the problems are from fall armyworms.

Hot, dry weather can intensify fall armyworm problems when egg-laying adults concentrate their eggs in irrigated, green turf.  At least some cultivars of all warm season grasses are susceptible.  Cool season grasses like tall fescue are very favorable for fall armyworm growth and development too, and do not regenerate as readily as the stoloniferous grasses.

Fall armyworm adults migrate northward every year from southern overwintering areas.  Adult armyworm moths are active at night and females lay eggs in masses of 50 to several hundred.  These night-flying moths are attracted to lights and to lighter colored surfaces.   Egg masses on structures around turf (eaves and gutters, fence and porch posts, flags on golf courses) and even on taller foliage plants can be the first indicators of incipient infestations.

Fall Armyworms in Turf
Small armyworms feeding on leaves. Photo by Kris Braman, UGA Entomologist

Eggs hatch in a few days, and the young larvae begin to feed on leaf tissue.  Damage from small larvae may at first look like skeletonizing, but as the worms grow, the entire leaf is consumed.  Small larvae at this time are easier to control and have inflicted less damage than full grown (35-50 mm long) larvae.  Full grown larvae will soon pupate in upper soil/thatch layer and will not be susceptible to insecticides at this point.

Armyworm larvae are most active early and late in the day, spending the hotter hours down near the soil in the shade. Larvae feed for 2 to 3 weeks before pupating in the soil.  Moths emerge 10 – 14 days later.  The entire life cycle from egg to adult moth takes about 28 days in the warm weather of August and September.

Fall Armyworms in Turf
Paper wasp eating caterpillar. Photo by Cheri Abraham, Field Operations Manager/ Entomologist at US Citrus, LLC

If there is any doubt about whether worms are present, pouring soapy water on the grass (1/2 oz. dishwashing soap/gallon water) will bring them up very quickly.  Heavily infested turf will also have visible greenish-black fecal pellets on the soil surface.  Other indicators of armyworm infestations may include birds or even paper wasps that use the fall armyworms as food.

Control of Armyworms

Control of armyworms and other turf caterpillars is relatively simple once the problem is identified.  There are several pesticides from which to choose depending upon the site you are treating. Consult the UGA Pest Management Handbook or your local Extension Agent for recommendations. Read and follow all label directions when using pesticides.

Armyworms are most active late in the day and at night, so pesticide applications should be made as late as practical for best results.  It is not necessary to water after application but an application rate of 20 – 25 gallons of solution per acre as a minimum will ensure good coverage. Cutting the grass prior to application may improve control, but do not cut grass for 1 –3 days after application.

In addition to the birds and paper wasps mentioned above, a number of other insects feed on armyworms, including tiger beetles and other ground beetles.  Fall armyworms, like many other turf infesting caterpillars can also be heavily parasitized by tiny wasps that kill the caterpillars and cause no harm to humans or pets.  These natural enemies can be conserved by spot rather than blanket spraying and properly timing control efforts.

Postemergence Bermudagrass Control in Turf

by

An excerpt taken from the publication Bermudagrass Control in Southern Lawns by Patrick McCullough, UGA Extension Weed Specialist

Find the entire publication here

Bermudagrass plants. (Photo - P. McCullough.)
Bermudagrass plants. (Photo – P. McCullough.)

Postemergence Herbicide Control

Postemergence herbicides may be applied to suppress bermudagrass populations and reduce competition with desirable turfgrasses. Repeat applications of selective herbicides are needed for best results but may be injurious to the desirable species. Furthermore, tolerance to herbicides may vary by turfgrass cultivar and end-users should consult with local Extension specialists for application rates and recommendations.

Bermudagrass Control in Centipedegrass

Centipedegrass is a popular low-maintenance lawn species in Georgia. Centipedegrass generally has slower growth than bermudagrass with less potential for competition during the summer. Clethodim (Envoy, others) and sethoxydim (Segment, others) are cyclohexenadione herbicides that inhibit lipid synthesis in grassy weeds. Sensitive species exhibit leaf injury with reddish discoloration before significant necrosis.

Bermudagrass is sensitive to both clethodim and sethoxydim and repeat applications may suppress populations in centipedegrass. Turf managers should schedule applications approximately every three weeks during active growth. For best results, add a nonionic surfactant at 0.25% v/v with clethodim to enhance spray retention and apply no sooner than three weeks after spring green up. Certain sethoxydim products (e.g., Segment) may have a built-in adjuvant already mixed in the formulation and the addition of a surfactant is not required. For both herbicides, turf managers should avoid mowing one week before or after treatment.

Bermudagrass Control in St. Augustinegrass

St. Augustinegrass is a major warm-season turfgrass used for lawns in southern Georgia. St. Augustinegrass has desirable heat and drought tolerance but is sensitive to many herbicides. Selective herbicides for controlling grassy weeds, such as crabgrass and goosegrass, are limited in St. Augustinegrass lawns. Bermudagrass infestations are also difficult to manage.

St. Augustinegrass has good tolerance to ethofumesate (PoaConstrictor, Prograss), which may be used in combination with atrazine to control bermudagrass. Ethofumesate is an unclassified herbicide that has postemergence activity for grassy and broadleaf weed control in nonresidential St. Augustinegrass and cool-season grasses. Ethofumesate has several toxic effects in susceptible species, such as bermudagrass, but arrested cell division appears to be the primary mechanism of selectivity.

Atrazine inhibits photosynthesis in susceptible weeds and is in the triazine herbicide family. Triazines interfere with electron transport during photosynthesis and eventually lead to cell membrane destruction and cellular leakage. Susceptible weeds initially exhibit chlorosis on leaf margins. Actively growing bermudagrass is sensitive to atrazine applications and its addition to ethofumesate treatments provides postemergence and some residual control of bermudagrass. Atrazine alone may provide some bermudagrass suppression but does not provide long-term control.

Applications of ethofumesate with atrazine should be initiated during bermudagrass spring green up. Herbicide regimens that begin on actively growing bermudagrass in summer will likely be ineffective. St. Augustinegrass often responds to applications with stunted growth and discoloration. Repeat applications should be made after 30 days or once turf has recovered from any potential injury. See the current edition of the Georgia Pest Management Handbook for rates and further information about bermudagrass control.

Bermudagrass Control in Tall Fescue and Zoysiagrass

Fenoxaprop and fluazifop are used for postemergence grassy weed control in tall fescue and zoysiagrass. Sensitive weeds exhibit injured leaf tissue with reddish discoloration while plant nodes become necrotic and die. Theses herbicides have no activity on broadleaf weeds but provide excellent grassy weed control.

Fenoxaprop (Acclaim Extra) and fluazifop (Fusilade) may be used alone in tall fescue and zoysiagrass lawns. Fenoxaprop may also be used in residential and nonresidential Kentucky bluegrass (Poa pratensis L.), perennial ryegrass (Lolium perenne L.) and other cool-season turfgrasses. Fluazifop may be used in commercial and nonresidential turf. Generally, tall fescue has good tolerance to these herbicides. There is greater potential for injury on zoysiagrass than on tall fescue from fenoxaprop or fluazifop treatments, especially fine-textured varieties.

Triclopyr (Turflon Ester, Turflon Ester Ultra) at high rates (0.75 to 1 lb ai/acre) is injurious to bermudagrass. Tank mixtures with fluazifop or fenoxaprop have been shown to reduce tall fescue and zoysiagrass injury without compromising control. The addition of an adjuvant to tank mixtures of fluazifop with new triclopyr formulations (e.g., Turflon Ester Ultra) is unnecessary and may increase turf injury.

In Georgia, initial applications of fenoxaprop or fluazifop should be scheduled around June 1 and repeated every 20 to 30 days. Fluazifop alone should be applied with a non-ionic surfactant at 0.25% v/v of spray solution. Acclaim Extra (fenoxaprop) does not require the addition of an adjuvant. See the current edition of the Georgia Pest Management Handbook for rates and application comments for fluazifop and fenoxaprop treatments for bermudagrass control in tall fescue.

Nonselective Bermudagrass Control

Spot treatments of nonselective herbicides are the most effective method for controlling bermudagrass. Glyphosate is a nonselective herbicide that is widely used for spot treatments of perennial weeds in turfgrasses. Glyphosate is a foliar-absorbed herbicide that is systemically translocated with no preemergence activity for weed control.

Spot treatments of glyphosate should be made to bermudagrass patches and surrounding areas to control any runners that may be intermingled with desirable turfgrasses. Broadcast applications can effectively renovate or kill existing vegetation but high rates and multiple applications are required to control bermudagrass. Glyphosate should be applied to actively growing bermudagrass. Repeat treatments will be required for complete control. Cultural practices that disrupt plant growth, such as vertical mowing and aerification, should be delayed for seven days after treatment.

Glyphosate requires optimum translocation in order to control bermudagrass rhizomes and plants emerging from lateral stems. Perennial grasses generally have greater translocation of photosynthate from leaves to stems in fall than spring, which increases glyphosate movement to rhizomes. Fall glyphosate applications generally control bermudagrass more effectively than summer treatments. Numerous glyphosate products are available under a wide variety of trade names.

Other information in this publication

For pesticide recommendations see the UGA Pest Management Handbook.

Bermuda postemergence control

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