Spring & fall are good times 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:

UGA Pest Management Handbook

Fire Ant Control Materials

Managing Imported Fire Ants in Urban Areas

Georgia lawns may show cold damage this spring

Sharon Dowdy is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.

Lawns in Metro Atlanta and north Georgia counties covered in warm-season grasses like centipedegrass or St. Augustinegrass will likely show signs of cold damage this spring as a result of the recent snow and ice storms, says University of Georgia Extension turfgrass specialist Clint Waltz.

“The temperatures were down in the single digits for 60 hours, so we are likely to see some losses, especially in common centipedegrass. Also, there is a lot of St. Augustinegrass in Atlanta, especially in shady areas. You’ll be able to see (the cold damage) when it doesn’t green up this spring,” said Waltz, a scientist in the UGA College of Agricultural and Environmental Sciences. “There’s still a little bit of a question mark about lawns in south Georgia.”

No protection

Homeowners and landscapers caring for common centipedegrass should not “be surprised to see it come out thin and spotty,” this spring he said. “It’s going to take a some work to get it back into shape over the summer growing season.”

Centipedegrass and St. Augustinegrass have no below ground rhizomes. They grow above the ground through stolons, or runners. This makes recovery and regrowth of these species more difficult.

Waltz says homeowners can choose to turn the cold damage into an opportunity for change.

Tifblair centipede - Georgia Integrated Cultivar Release System
Tifblair centipede – Georgia Integrated Cultivar Release System

“With the potential loss of some centipedegrass and St. Augustinegrass, this would be the year to consider converting your lawn to something more cold hardy like zoysiagrass. Then you won’t have to worry about every ninth year when we get a very cold winter,” he said.

For those who decide to change to a new turfgrass variety, Waltz recommends cold hardy UGA-bred TifBlair centipedegrass or a zoysiagrass variety. “Zoysiagrass is pretty cold hardy species. I’d be surprised to see it damaged,” Waltz said.

Time will tell for bermudagrass

Waltz is unsure what’s ahead for homeowners with bermudagrass lawns. “If you could tell me what the weather is going to be like, I can tell you how the grass is likely to recover,” he said. “If the weather warms up and stays warm, then bermudagrass will probably be fine, but if we get another snow or if it drops down into the teens after we have 30 to 50 percent green-up, the cold snap will cause the grass to go dormant, and it is possible it won’t green-up again.”

Warm temperatures tell the grass it’s springtime, but when temperatures drop, the plant doesn’t know how to respond, he said. If early April brings 65 degree temperatures, the grass will begin to sprout. If a late frost occurs, the new “succulent grass tissue” can be lost, Waltz said.

“Tifway is not a particularly cold hardy cultivar of bermudagrass. TifSport, TifGrand and Patriot are and will likely do fine,” Waltz said.

Homeowners can help their bermudagrass lawn by doing nothing.

“After the cold we’ve had, there is really nothing you can do. Just let (the lawn) green-up on its own and don’t fertilize it,” he said.

Don’t listen to the commercials

Ignore television commercials, radio and print ads that advise fertilizing lawns.

“Don’t listen to the marketing when they say ‘Now is the time to fertilize,'” Waltz said. “When we get into March Madness and you start hearing the personalities that know sports but don’t know about turfgrass tell you to fertilize your lawn, disregard all that.

“Clint Waltz is telling you that when it comes to warm-season grasses hold off on that first nitrogen application until late April or early May,” he said.

Bermudagrass, centipedegrass, St. Augustinegrass and Zoysiagrass should be fertilized when the soil temperature is consistently 65 degrees and rising at a 4-inch soil depth, he added. Usually this is late April or early May in Metro Atlanta.

For more on turfgrasses in Georgia, see the UGA Extension website www.GeorgiaTurf.com.

2014 Sod Producers’ Survey examines inventory and price

Sod harvesting, Rachel McCarthy, Cornell University – NEPDN, Bugwood.org
Sod harvesting, Rachel McCarthy, Cornell University – NEPDN, Bugwood.org

In October 2013, the Georgia Urban Ag Council conducted the twentieth consecutive survey of sod producers.  The purpose of the survey was to determine the status of inventory levels and projected price changes for spring 2014.

Summary of key points from the 2014 Sod Producers Survey

  1. Bermudagrass and zoysiagrass supply is low, regardless of grower category.
  2. The delivered price for bermudagrass, centipedegrass, and St. Augustinegrass are expected to increase by more than 13%.
  3. Bermudagrass and centipedegrass prices are at historic levels.
  4. Considering the “big 3” species (i.e. bermudagrass, centipedegrass, and zoysiagrass), the preponderance of growers anticipate rising prices in 2014.
  5. 2014 continues a seven year trend of increasing average prices for certified grass.
  6. Freight rates per mile shipped to Atlanta, or within 100 miles of the farm, are unchanged from 2013.
  7. Fewer growers reported adding a fuel surcharge in 2014.
  8. No grower expects to remove acres from turfgrass production.
  9. More turfgrass acreage could come into production in 2014.
  10. The primary markets for Georgia sod are landscape contractors and homeowners.
  11. Get price quotes regularly.
  12. If possible “book” or lock prices to ensure availability and price.

See the entire survey here or visit Georgiaturf.com.

UGA mobile apps help professionals care for lawns

Sharon Dowdy, News Editor with the UGA College of Agricultural and Environmental Sciences

Four mobile applications designed by University of Georgia specialists are putting lawncare information at your fingertips, literally.

The turfgrass apps created by UGA College of Agricultural and Environmental Sciences faculty make turf management in Georgia readily available. Turfgrass Management, Turf Management Calculator, Turfgrass Weeds and Turf Management Quiz can all be downloaded from the UGA Turfgrass Team website at www.GeorgiaTurf.com or straight to a mobile device through iTunes.

A lite version

The most popular UGA turfgrass app is Turf Management Lite. This free app was created with students, homeowners and professionals in mind. It includes photos of turfgrass varieties, pests, weeds and diseases.

Mobile applications, or apps as they are commonly called, can be downloaded onto smart phones like Droids and iPhones as well as portable tablets like iPads.

“Back in 2009, mobile apps were fairly new to smart phones. We saw a great opportunity to put the information where it can be easily accessed by mobile phone, iPods and tablets, instead of publishing a telephone-book-sized publication,” said Patrick McCullough, a UGA turfgrass specialist based on the Griffin campus. The turfgrass apps are his brainchild.

“Rather than have to go to the office and get an Extension publication or go online to view a publication, turfgrass professionals can now access the information they need in the field,” he said.

In-depth subscription version

There are three versions of the first app: Turf Management Lite, Turf Management Subscription and Turfgrass Management – Spanish. The lite and Spanish versions are free, but the subscription version costs $20 per year.

The subscription version includes everything from the lite version, plus information on pest control applications and a pesticide database. “You can search for trade names as well, and it includes PowerPoint presentations from UGA turfgrass faculty,” McCullough said.

The Spanish version is very popular in the turfgrass industry. “We have folks in the industry that speak Spanish as their first language. This app is a nice opportunity for those who are fluent in Spanish or primarily communicate in Spanish at work to have research-based turfgrass advice,” he said.

The Spanish version has been downloaded in more than 40 countries across the globe.

Making calculations easy

In 2011, the Turfgrass Management Calculator app was released. “It’s a comprehensive program that covers all types of applications, pesticide rates, fertilizer requirements, topdressing sand requirements, and calibration of sprayers and spreaders. Users enter known values of equations – like how much area is needed for a pesticide treatment at a certain rate. The app then does the calculation for you,” McCullough said.

College students majoring in turfgrass management use the app to double-check their math when learning these calculations, he said. “Some of these are very complex formulas. You can enter information for two products with different application rates and see which is more cost effective.”

The calculator app costs $5 and includes more than 16,000 pre-programmed calculations. It can also convert units from standard to metric. “It’s really a great tool for turfgrass managers and professionals, but students can learn a lot from it, too,” McCullough said.

Flash cards and quizzes

The Turfgrass Weeds app was released in 2011. It is designed to help users learn turfgrasses and weeds through a series of flash cards. “The cards reshuffle so users can continue to study and learn turfgrass species and weeds,” he said.

Just a few months ago, the UGA Turfgrass Team released its latest turfgrass app – Turfgrass Management Quiz.

“This app is a trivia style education game. You get test questions or photos with four choices to answer. You tap the correct answer, and when you’re done, you get a quiz score,” McCullough said.

The quiz app has two modes – quiz mode and study mode. Quiz mode scores your answers and study mode helps you get the correct answer.

“This app is perfect for students, but it can also be used by any turfgrass professional who wants to brush up on their knowledge. It’s a fun application that challenges you to get the best score, improve on your score and test your knowledge,” he said.

The new turfgrass apps are perfect for those who like to learn on their phones or mobile devices. UGA publications are also available online for computer users and in print form for those who still like the feel of a book in their hands.

“(Mobile apps) are a new technology – a new method to get information in the hands of the end user. We are trying to make it easier for people to get UGA turfgrass recommendations so it just makes sense for us to create these programs,” McCullough said.

To download the UGA turfgrass mobile apps or get more information on the turfgrass research at UGA, see the website www.GeorgiaTurf.com.

Insecticide application timing vital to protecting bees

Editor’s note – The recent bee kill in Oregon and the resulting statewide temporary restriction of one of the neonicotinoid insecticides highlights the need to be careful in timing neonicotinoid insecticide applications and using these pesticides safely.

See original article from SR IPM here

Katie Pratt, UK Agricultural Communications specialist
Jonathan Larson is looking at ways that people can safely use insecticides and not affect native pollinators. Image – Katie Pratt, UK Agricultural Communications specialist

Many homeowners may grimace at the sight of grubs, caterpillars or other pests lurking in their lawns, but understanding when and how to apply an insecticide to control these pests could have a big impact on native pollinator populations, according to a researcher from the University of Kentucky College of Agriculture, Food and Environment.

Jonathan Larson, a UK doctoral student, has found that when neonicotinoids, a type of systemic insecticide, are applied to flowering lawn weeds that are frequented by native bees, such as dandelions and white clovers, the chemicals can negatively impact local pollinator populations.

While honeybee population decline has received much attention, bumblebee numbers have also been on the decline. Much like honeybees, bumblebee population decline is related to diseases, pesticides and habitat loss or fragmentation.

“With honeybee populations struggling, we need to rely on native bees, such as bumblebees, to pick up the slack on plant pollination,” said Dan Potter, UK entomologist and Larson’s adviser. “Many native bees are much more efficient at pollinating certain types of crops, like tomatoes, urban flowering plants and vegetables grown in home gardens.”

Larson’s research, published in the journal PLOS ONE, showed that exposure to clothianidin, a neonicotinoid insecticide, negatively affected queen production. It also slowed foraging and caused higher mortality rates in worker bees within five days after exposure at plots on UK’s Spindletop Research Farm compared to control hives. When moved to an untreated field to forage for six weeks, the bees had a hard time gaining weight compared to the controls. Bumblebees exposed to chlorantraniliprole, from a relatively new class of lawn insecticides, developed and reproduced normally compared to the control hives.

“We’re trying to figure out ways that people can safely use insecticides and not affect native pollinators,” Larson said. “One way may be for homeowners and commercial lawn care professionals to use the newer class of insecticide instead of a neonicotinoid to control common lawn pests. Another way could be mowing treated areas.”

He found that when clover flowers treated with an insecticide are removed by mowing and new flowers grew to replace them, neither insecticide adversely affected bumblebee colonies.

“Direct contamination of the flowers is the problem, so homeowners need to remove the flower heads of weeds either before or after applying an insecticide to prevent exposure to native pollinators,” Larson said.

Larson is now studying the level of insecticides present in the nectar of subsequent generations of clover flowers after the field has been treated with an insecticide and the treated flowers have been removed.

The entire PLOS ONE article is available here.

Contact: Dan Potter, 859-257-7458; Jonathan Larson, 859-257-7475

Writer: Katie Pratt, 859-257-8774

The original release and photos can be found here.

Inquiries about Fairy Ring, Mushrooms, and puffballs in turfgrass continue to be common

Inquiries about fairy ring, mushrooms and puffballs in turfgrass continue to be common

There are three types of fairy rings based on the symptoms they produce.

  1. Type I. Grass is badly damaged or killed.
  2. Type II. Grass growth is stimulated.
  3. Type III. Grass growth is not influenced by the fairy ring. The only evidence of the fairy ring is the presence of fungal fruiting bodies.

The type III fairy ring symptoms are more predominant during prolonged periods of wet weather, while Type I and Type II fairy ring symptoms are common during hot, dry weather in the summer.

The most effective means for fairy ring control is to prevent the causal fungi from becoming established in the turf. It’s advisable to remove large pieces of woody material such as stumps, dead tree roots and other organic/woody debris before turf is planted to prevent the establishment of fairy rings.

Fairy rings thrive on organic matter; therefore, changing the organic content in the soil by spike/core aeration and thatch reduction can help to control fairy ring. Water and fertilize declining area inside ring appropriately to stimulate new turfgrass growth.

In golf course settings, the use of fungicides is an option to control fairy ring while corrective cultural measures are taken.

More information on fairy ring can be found at:

Turfgrass Diseases in Georgia: Identification and Control

Turf Disease Control Recommendations

Fall Turfgrass Disease Control

Severe leaf and crown rot, caused by Bipolaris sp. can occur in bermudagrass lawns, sport fields, or golf fairways. Initial symptoms of this disease include brown to tan lesions on leaves. The lesions usually develop in late September or early October. Older leaves are most seriously affected.

Under wet, overcast conditions, the fungus will begin to attack leaf sheaths, stolons and roots resulting in a dramatic loss of turf. Shade, poor drainage, reduced air circulation; high nitrogen fertility and low potassium levels favor the disease.

To achieve acceptable control of leaf and crown rot, early detection (during the leaf spot stage) is a crucial.

Large Patch

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 zoysiagrass, centipedegrass, St. Augustinegrass and occasionally bermudagrass.

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. There are a myriad of fungicides that can help to control the disease. Preventative or curative rates of fungicides (depending on the particular situation) in late September or early October and repeating the application 28 days later are effective for control of large patch during fall. Fall applications may make treating in the spring unnecessary. Always follow label instructions, recommendations, restrictions and proper handling.

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.

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.

Spring Dead Spot of Bermudagrass

The causal agents of Spring Dead Spot (SDS) are most active during cool and moist conditions in autumn and spring. Appearance of symptoms is correlated to freezing temperatures and periods of pathogen activity. Additionally, grass mortality can occur quickly after entering dormancy or may increase gradually during the course of the winter. Spring dead spot is typically more damaging on intensively managed turfgrass swards (such as bermudagrass greens) compared to low maintenance areas.

Management of Spring Dead Spot

Practices that increase the cold hardiness of bermudagrass generally reduce the incidence of spring dead spot. Severity of the disease is increased by late-season applications of nitrogen during the previous fall.

Management strategies that increase bermudagrass cold tolerance such as applications of potassium in the fall prior to dormancy are thought to aid in the management of the disease. However, researchers have found that fall applications of potassium at high rates actually increased spring dead spot incidence. Therefore, application of excessive amounts of potassium or other nutrients, beyond what is required for optimal bermudagrass growth, is not recommended.

Excessive thatch favors the development of the disease. Therefore thatch management is important for disease control,

  • Implement regular dethatching and aerification activities.
  • There are several fungicide labeled for spring dead spot control.
  • Fall application of fungicides is essential for an effective control.

Publication on Identification and Control of Spring Dead Spot

Additional information can be found at:

Turfgrass Diseases in Georgia

Georgia Turf

Pest Management Handbook (Follow all label recommendations when using any pesticide)

Fall Interseeding and Overseeding: Not One and the Same

Photo by Wayne Hanna, Professor, UGA Crop & Soil Sciences
Photo by Wayne Hanna, Professor, UGA Crop & Soil Sciences

Clint Waltz, Ph.D., UGA Turfgrass Specialist

It’s nearing that time again, time to think about fall interseeding and overseeding.  These two practices are similar but technically not the same.  Interseeding is the practice of seeding the same species into itself for the purpose of increasing stand density and recovery of lost grass.  For example, tall fescue is interseeded into tall fescue in the fall to improve the overall stand which may have declined through the summer stress period.  Different cultivars may be used but the turfgrass species remains constant.  Adding centipedegrass seed to a thin centipedegrass lawn in the spring is another example where like species is seeded into like species.

Prior to interseeding, particularly with tall fescue, core aeration is a common practice.  The benefits for core aeration are numerous (e.g. soil air exchange, relieving compaction, improved water infiltration, etc.), including improving a planting or seed bed conditions.

Overseeding, however, is the practice of temporarily introducing a second turfgrass species – typically a cool-season grass – into a permanent species – typically a warm-season species – for the purpose of winter color or traffic tolerance.  An example of overseeding would be incorporating a second, or temporary, species into a permanent species, as in overseeding a bermudagrass baseball field in the fall with perennial ryegrass to have a green field in the early spring.  The second species can compete with the permanent species for light, water, space, and nutrients, so overseeding can become an additional stress that has to be managed.  Of the warm-season turfgrasses, bermudagrass is best adapted and tolerant of overseeding.  It is ill-advised to overseed solely stoloniferous grasses like centipedegrass and St. Augustinegrass.

Successful overseeding involves growing healthy grass prior to overseeding, proper seed and seeding rate selection, overseeding timing and preparation, post planting maintenance, and spring transition.  It is particularly important to maintain proper soil fertility, to relieve soil compaction, and to prevent excessive thatch development.

Overseeding selection involves selecting grasses that have characteristics suited to the particular needs.  Annual ryegrass has been replaced by perennial ryegrasses, because of improved turf quality, color, stress and pest tolerance, and manageability.  The “intermediate” ryegrasses tend to perform as the name implies somewhere between annual and perennial ryegrass, unfortunately most are more like annual ryegrass, not half way between the two.

Overseeding rates generally range between 5 and 10 pounds per 1000 ft2 in lawns.  In higher traffic situations, like sports fields and golf courses, the seeding range is between 8 and 12 pounds per 1000 ft2.  Using high quality “Certified” (blue tag) seed that is free of weed species is important to maintaining quality turf.  It is also important to use seed treated with fungicides such as Apron particularly for early fall overseeding since seedling blight diseases can be a problem.

The ten pound seeding rate generally provides a rapid stand for fall use, while the five pound rate provides a thinner stand and may not provide much coverage until spring.  Seeding rate generally relates to desired appearance and intended traffic or use.  Higher trafficked areas need higher seeding rates.  However, higher seeding rates may lead to more difficult spring transition.  Balancing seeing rate with need and desired appearance is a management decision that can affect bermudagrass the following fall, so seed appropriately.

Proper timing of overseeding should result in a gradual transition from the warm-season turf to cool-season turf.  Some common indicators that tell us it is time to overseed include:  soil temperatures at a four‑inch depth approaching 75° F, night temperatures falling into the 50’s, average midday temperature in the mid-70° F, or 2 to 4 weeks before the average annual first killing frost date.

The objective to insuring a successful overseeding is good soil to seed contact.  Seedbed preparations generally consist of close mowing or scalping, with some light vertical mowing, and blowing, sweeping, or vacuuming the loose plant debris from the soil surface.  Generally, the more the turf is opened, the better the establishment rate, but the more competitive the cool-season turf will be in the spring.  Seed which germinate in thatch or above the soil surface are more likely to dry-out and die before becoming established.

After dragging the seed into the soil, begin lightly irrigating to maintain good surface moisture and get the seed to germinate.  This generally means irrigating three to five times per day until the seedlings are well established, but the total amount of water applied during a day would seldom exceed 0.5 inches.  This irrigation practice should be done without causing puddling on the soil surface, free water encourages disease.  After germination, gradually reduce the frequency and increase the time of irrigation until a normal irrigation program can be established.

Begin mowing when seedling height is 30% higher than desired.  Use a mower with sharp blades and mow when the grass is dry to reduce seedling injury.  Because first-mowed grass is tender and succulent a reel-type mower tends to lay seedlings over and not cut them.  Using a rotary-type mower is commonly used for the first mowing with the fear of “ripping” seedlings being unfounded or insignificant.  Transitioning to a reel-type mower after the second or third mowing can provide a high quality appearance.

Wait to fertilize after seedling emergence (generally three weeks after seeding) since earlier fertilizing may encourage warm-season turf competition.  One pound of N per 1000 ft2 per month is adequate with less (e.g. 0.25 to 0.75 lb N / 1000 ft2) commonly used.  Use a soil test report to guide phosphorus needs but it is typical to apply some phosphorus shortly after seeding to improve rooting.

2013 reports show ryegrass and tall fescue seed crops being harvested earlier and faster than normal.  This may not indicate a bountiful year for seed production.  In fact, the forecast is for an average yield with a reduced quality due to more contaminants (i.e. weeds) in the seed fields.  Combine these factors with short carryover inventories and reduced acres in production, the result may be higher seed prices for 2013.

Fall is rapidly approaching and seeding, be it interseeding or overseeding, will again be part of turfgrass management programs.  Proper preparation prior to seeding and sound management afterward can provide a turfgrass surface that performs well and is attractive throughout the winter.

Prepare Now for Annual Bluegrass (Poa annua) Emergence this Fall

Prepare Now for Annual Bluegrass (Poa annua) Emergence this Fall

Patrick McCullough, Extension Weed Specialist, University of Georgia

Annual weeds establish from seed and complete their lifecycle in one year.  Summer or warm-season annual weeds (like crabgrass) establish in spring, grow actively in summer, and die out in fall.  Winter or cool-season annual weeds (like annual bluegrass) establish in fall, grow from fall to spring, and complete their lifecycle in warm temperatures in late spring.

Failure to control annual weeds in late summer may predispose turfgrasses to winter weed infestations.  In many lawns, it is fairly common to see turf with significant summer crabgrass populations have problems with annual bluegrass in fall.  Open areas left in turf where crabgrass was once actively growing may permit annual bluegrass invasion during periods of peak seed germination.  Controlling crabgrass now or in late summer could significantly improve turf cover, growth, and competition with annual bluegrass.  See Table 1 for postemergence herbicide selection for crabgrass control in turf.

Late Summer Crabgrass Control Can Improve Annual Bluegrass Control This Fall

Prepare Now for Annual Bluegrass (Poa annua) Emergence this Fall
Crabgrass Seedhead – Ted Bodner, Southern Weed Science Society, Bugwood.org

Quinclorac is a popular postemergence herbicide selection for crabgrass control in bermudagrass, zoysiagrass, and many cool-season grasses.

Single applications of quinclorac have excellent activity on mature, multi-tiller crabgrass plants at the seedhead stage in late summer.  Bermudagrass, creeping bentgrass, perennial ryegrass, tall fescue, and zoysiagrass can be safely seeded seven days after a quinclorac application.  Quinclorac requires the addition of an adjuvant, such as crop oil or methylated seed oil, for best results in established turf.

Mesotrione (Tenacity) can be used for postemergence crabgrass control in centipedegrass, perennial ryegrass, St. Augustinegrass, and tall fescue.

Mesotrione should be applied with a nonionic surfactant and will require two applications at a three week interval for late summer crabgrass control.  These turfgrasses can also be safely established following mesotrione applications for crabgrass control.  Currently, Tenacity can be used in nonresidential turf but will have residential lawns added to the label in the near future.

Fenoxaprop (Acclaim Extra) is a postemergence grassy weed herbicide for use in tall fescue, perennial ryegrass, and zoysiagrass.

Fenoxaprop has excellent activity on multi-tiller crabgrass with one application but efficacy is often reduced when crabgrass has seedheads present.  Tall fescue and perennial ryegrass may be safely reseeded immediately after fenoxaprop applications.  Late summer seeding of zoysiagrass is not recommended but newly plugged or sodded zoysiagrass may be treated with fenoxaprop.

Other herbicides for postemergence crabgrass control in centipedegrass, such as clethodim (Envoy) and sethoydim (Segment, others) may require two treatments at three to four week intervals to control mature, multi-tiller crabgrass.

These herbicides should not be used in centipedegrass lawns with significant bermudagrass infestations due to sensitivity and excessive injury to bermudagrass.  Early fall seeding of centipedegrass is not recommended but turf managers should modify cultural practices to encourage turf to fill in areas where crabgrass was present before annual bluegrass begins to germinate.

Late Summer Cultural Practices to Reduce Annual Bluegrass Competition

Prepare Now for Annual Bluegrass (Poa annua) Emergence this Fall
Annual bluegrass, Joseph M. DiTomaso, University of California – Davis, Bugwood.org

Promoting turfgrass recovery from summer stress is critical to reduce annual bluegrass competition in fall.

Review cultural practices and make modifications if needed for lawns with crabgrass problems during summer months.

Mowing height significantly influences turfgrass competition with crabgrass, annual bluegrass, and other problem weeds.

Height of cut for most lawns should be no less than two inches.  Raising the mowing height of tall fescue, for example, to three inches may significantly reduce annual bluegrass establishment in fall and reduce the need for postemergence herbicides in spring. Check mowing height for your turf-type.

Mowing frequency also influences turfgrass growth and susceptibility to annual bluegrass infestations.

Turf managers should mow lawns at least once per week during periods of vigorous growth to prevent scalping.  Scalping thins out turf and may enable annual bluegrass establishment in open areas.  While returning clippings is recommended to recycle nutrients to the soil, removal of clippings may be useful when annual bluegrass is present and producing seed heads. Removing clippings at this time will reduce the spread of viable seed through the lawn.

Encouraging turf recovery from summer stress may include modifications to fertilization programs.

Turf managers should consider reducing nitrogen fertilization during peak annual bluegrass germination and during periods of vigorous growth (cool weather).  High nitrogen at these times encourages annual bluegrass spread and survival into winter and spring.  Fertilizing dormant turfgrasses when annual bluegrass is actively growing will make these weed infestations worse.

Fall aerification of cool-season grasses may also influence annual bluegrass infestations.

Open areas of bare soil in turf following an aerification may encourage annual bluegrass infestations during periods of peak seed germination.  Time aerifications in early fall to allow turf to recover before annual bluegrass germinates.