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,

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,

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.

Preemergence Herbicides for Annual Bluegrass

Patrick McCullough, Extension Weed Specialist, University of Georgia

Preemergence herbicides may prevent annual bluegrass infestation via seed and limit current infestations from further spreading.  However, preemergence herbicides will not eradicate established plants and will not effectively control perennial biotypes of annual bluegrass from spreading vegetatively.

Poa annua, Joseph M. DiTomaso, University of California - Davis
Annual Bluegrass, Joseph M. DiTomaso, University of California – Davis,

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.  This info on timing herbicide application is taken from an article online by Tim Murphy, UGA Weed Scientist. “Annual bluegrass germinates in the late summer and early fall when daytime temperatures consistently drop into the mid-70os and nighttime temperatures are in the mid-50os for several days. In the Piedmont of Georgia for winter annual weed control, apply the preemergence herbicide sometime during the first two to three weeks of September (by September 20). In north Georgia, the last week of August up to about September 15 would be the preferred time. In South Georgia, the application should be made during the mid-September to mid-October time frame.”

A second herbicide application can be applied in spring to control germinating plants.  Fall applied preemergence herbicides cannot be used if reseeding or re-sodding is needed to repair areas of damaged turf within several months after herbicide applications.

Several preemergence herbicides effectively control annual bluegrass in fall and winter which are similar to products used for summer annual weed control (Table 2).  These herbicides include dithiopyr (Dimension), oxadiazon (Ronstar, Starfighter), pendimethalin (Pendulum, others), and prodiamine (Barricade, others).

Combination herbicide products are also available which may improve efficacy of applications.  These products include oxadiazon plus bensulide (Anderson’s Crab and Goose) and benefin plus oryzalin (Team 2G or Team Pro).  Many preemergence herbicides are available under a wide variety of trade names and formulations. Carefully read and follow label instructions before applying products.

Most preemergence herbicides will provide similar initial efficacy if applied before annual bluegrass germination and if 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 upper 1/3 inch of the soil profile.  Avoid herbicide retention on leaves and incorporate the herbicide into the soil by irrigating turf immediately after application.

Table 1.  Efficacy of postemergence herbicides for crabgrass control in turfgrasses.  See labels for turf tolerance and areas for use.

Postemergence Herbicides for Crabgrass Control

Common Name Trade Name (Examples)


Clethodim Envoy


Fenoxaprop Acclaim Extra


Mesotrione Tenacity


Quinclorac Drive, Drive XLR8


Sethoxydim Segment, others


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


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

Preemergence Herbicides for Annual Bluegrass Control

Common Name Trade Name (Examples)


Atrazine Aatrex, others


Benefin Balan


Bensulide Betasan, others


Dithiopyr Dimension


Ethofumesate Prograss


Mesotrione Tenacity


Oryzalin Harrier, Surflan


Oxadiazon Ronstar, Starfighter


Pendimethalin Pendulum, others


Prodiamine Barricade, Cavalcade, others


Pronamide Kerb


Simazine Princep, WynStar, others


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


Helpful publications from UGA Extension on controlling annual bluegrass


Annual Bluegrass Control in Residential Turfgrass

Patrick McCullough, Extension Weed Specialist

This publication describes methods of control for annual bluegrass in residential turfgrass lawns.

To see the entire publication go here.



Annual Bluegrass Control in Non-Residential Commercial Turfgrass

Patrick McCullough, UGA Department of Crop and Soil Science

Accessible Training for the Landscape & Turf Industries

Online training

The Safety Makes Sense: Landscape Worker Safety Certificate Course is available at no charge on Vimeo (  With this tool, you can train on your time schedule, rainy day or any day.  The training video (a compilation of the Safety Makes Sense series) can be viewed online.  It can also be downloaded and saved for use when Internet is not available.  The course study guide and supervisor’s key provide talking points and a quick review.  Upon successful completion of the evaluation (70% or better), workers are emailed Certificates of Completion.

The publication Safety Checklists for New Landscape Employees is designed to assure and document safety training for new employees, these well-illustrated checklists are suitable for use with both English and Spanish speakers.  They cover general safety precautions, equipment safety, mower safety and basic pesticide safety.

The bilingual safety manual, Safety for Hispanic Landscape Workers, is available Online or For purchase

All center safety training resources and Hispanic worker resources are available on the UGA Center for Urban Agriculture web site at Safety Makes Sense.

UGA offers a monthly webinar for the landscape industry. Past classes are also archived for viewing online.

The Urban Ag Council has an excellent collection of Safety Zone training materials. Part of this collection of training materials is the Safety School.

Just In Time Disaster Training videos cover disaster related preparedness, safety, response and recovery training for a wide variety of areas.

eXtension is a web-based collaboration of land-grant universities across the US to make university educational resources more accessible. You can learn more about the initiative here –

eXtension Learn offers online classes covering numerous topics including pest control, landscaping, info technology and other topics. You can register to be reminded of upcoming trainings, access trainings online and view archived trainings at

eLearn Urban Forestry Online Training – The Office of the Southern Regional Extension Forester, the USDA FS Region 8–Urban and Community Forestry Program along with the Southern Group of State Foresters have partnered to design, develop and implement a state-of-the-art online, distance-learning program geared specifically toward beginning urban foresters and those allied professionals working in and around urban and urbanizing landscapes

To access the modules for free, please visit

To access the modules for International Society of Arboriculture and Society of American Foresters credit, please visit

To access the modules for volunteer credit or a certificate of completion, visit  and look for the eLearn Urban Forestry–Citizen Forester course.

For more specific information, please contact Sarah Ashton, Educational Program Coordinator, Southern Regional Extension Forestry at .

Pesticide Applicator Training

A Commercial Pesticide Applicator’s License is required for a person who applies pesticides to the land of another person for hire, or who manages these type pesticide applications. A firm applying pesticides for hire must also have a Pesticide Contractor’s License. Both of these licenses can be obtained through the Georgia Department of Agriculture.

For more information on training for these licenses

See this site to order study materials or to sign up for exams

The Georgia Competent Applicator of Pesticides Program (GCAAP) is a comprehensive training tool for pesticide technician and handlers. GCAPP offers training for pesticide applicators that do not have a commercial license.

Commercial applicators of mosquito control products need to have pesticide applicator certification in Category 41, Mosquito Control. UGA Entomologist Elmer Gray has recorded an online video to better prepare applicators to take and to pass the Category 41 pesticide exam.

Video Training

The Super Crew Employee Training for Landscape Professionals has several videos that can be purchased for training landscape workers. See the list of titles.

The Super Crew training series is also available in an online option.


The Georgia Certified Landscape Professional (GCLP) program is a voluntary testing program that certifies those in the landscape profession who have mastered a thorough knowledge and understanding of job skills required to be successful in the industry. The Georgia Certified Plant Professional program (GCPP) certifies plant professionals for the retail and wholesale ornamental plant industries.

The UGA Center for Continuing Education offers several online certifications:

Email Newsletters

Landscape Alerts for the landscape and turf industry are released as needed. See past issues here or subscribe by emailing

Pest Control Alerts update the structural pest management industry. See past issues here or subscribe by emailing

Pesticide Related Resources

Information about specific pesticides or other info – National Pesticide Information Center – (800) 858-7378

Information about risks of specific pesticides:

Extension Toxicology Network

Especially note the PIPS or Pesticide Information Profiles

Other pesticide information

Contact your Local UGA Extension Office

Locate your local UGA Extension Office

Call your local UGA Extension Office – 800-ASK-UGA1 (800-275-8421) from any non-mobile phone.

Designing a Quality Control Program for Your Landscape Company

Bodie Pennisi, Department of Horticulture and Willie Chance, Center for Urban Agriculture

Well-groomed landscapes are often a result of considerable effort by landscape companies. Employees make them happen with routine care and, above all, attention to detail. A quality landscape and the image employees present on the job speak highly of the professionalism of the firm. Quality control (QC) is everyone’s responsibility and an essential part of a landscaper’s job. This publication describes the basics of creating and implementing a successful QC program for your landscaping company. See the entire publication

Topics include:

Hummingbirds don’t fly after dark – hummingbird moths do

Nancy Hinkle, UGA Extension Entomologist

Remember that big green worm with the red horn on its tail that was eating your tomato plants in July? Well, over the last month it has burrowed into the soil, pupated, and emerged as a big moth that shows up after sunset and feeds from flowers at night.

The moths are called “hummingbird moths” because they look and act so much like hummingbirds, being able to hover over a flower and drink from it in flight. Also, like hummingbirds, they are fast fliers, zipping back and forth among blossoms. The moth’s tongue is actually longer than its body, allowing it to extract nectar from deep-throated blossoms.

These hummingbird moths, which are also called sphinx moths, can have wingspans up to 4 inches. The moths are gray with darker gray and black markings, and they have yellow or orange spots on the sides of their abdomens.

The moths’ larvae, those green caterpillars known as hornworms, feed on Solanaceous plants like tomato and tobacco. They have also been found on potato, eggplant and peppers, and they can thrive on these plants’ wild relatives such as jimsonweed, tropical soda apple and horse nettle.

Tomato hornworms and tobacco hornworms are similar in appearance and behavior, and both feed on tomato and tobacco plants.

The larvae are harmless to humans; the red horn on the rear end is flexible and cannot stick you. The best way to manage the pests is to be vigilant and pick each caterpillar off the plant as soon as you see it. Save it, and you can give it to a local schoolteacher for classroom demonstrations.

After the larva has fed to fullness, and is about 3 or 4 inches long, it crawls down into the soil and changes into the pupal stage. The pupa is distinctive in having a loop, almost like a shepherd’s crook, at one end; this is where the mouthparts of the adult moth form.

The reddish-brown pupa will remain underground until next spring when the adult moth will emerge from the pupal skin, through the soil and start the cycle all over again. If your garden is already planted when these moths emerge in the spring, they may lay their first batch of eggs on your young tomato plants, so keep an eye out for hungry caterpillars.

Dr John Ruter to lead UGA Trial Gardens

Dr John Ruter, UGA Horticulturist

Merritt Melancon, University of Georgia 

After 30 years, the Trial Gardens at UGA — that green, flower-laden oasis sandwiched between Snelling Dining Hall and the College of Pharmacy — is being tended by a new green thumb.

Dr John Ruter, UGA Horticulturist
Image Credit John Ruter

UGA Department of Horticulture professor John Ruter took over the day-to-day operations from garden co-founder Allan Armitage on July 1. Armitage is officially retiring at the end of 2013. He originally retired in 2010 and came back halftime.

Ruter has spent more than two decades as a horticulture professor and a nursery crop research and Extension specialist on the UGA Tifton campus, where he also ran the Coastal Plain Research Arboretum.

He moved to the Athens campus in 2012 after he was awarded the Allan M. Armitage Endowed Professorship for Herbaceous Plant Instruction and Introduction. He now teaches classes in plant identification and environmental issues in horticulture.

Ruter doesn’t want to rustle too many leaves as he eases into his new role, but he does want to spruce up the garden a bit — mostly planning changes to attract new visitors, allow it to run more efficiently and be used for more horticulture classes.

“I’m just starting with it, but I do have lots of ideas,” Ruter said.

While the Trial Gardens serves as a testing ground for new plant varieties, it’s also an integral part of the UGA Department of Horticulture’s teaching and research programs. It’s important to Ruter to maintain all the facets of the garden’s mandate.

Plant nurseries and breeding companies send hundreds of new plants each year to see if they can survive the hot and rainfall variable Southeast. They fund the garden by paying to have their plants evaluated by an outside source. That money pays for the gardens’ upkeep and a team of student workers who keep the garden running.

While providing an important link with the green industry, the garden is also a research lab, where Ruter will work with graduate students to develop new plant varieties, and a classroom for plant identification and other horticulture courses.

Ruter plans to make the garden more useful as a teaching tool by planting more perennials and annuals that bloom in fall and early spring when classes are in session. This will also be good for the entomology, plant biology, plant pathology, landscape architecture and visual arts instructors who also use the garden as an outdoor classroom.

“We’re still going to get some perennials in there for evaluation, and they will always be there,” Ruter said. “We will always have a majority of summer blooming plants, but maybe we can have some other things that we can use for teaching purposes and that can help make (the garden) a little more showy other times of the year — rather than just during the summer.”

Planting for a more diverse blooming schedule will also bolster the garden’s reputation as a destination — both for visitors to the Classic City and for Athens’ residents. Support on-campus and from the general public will be integral to maintaining it as green space on campus for decades to come, Ruter said.

Like in every other part of the university, Ruter, Meg Green (Trial Garden supervisor), and her team of student workers and volunteers are operating within tighter budget constraints.

“We’re trying to make some renovations to the perennial gardens and work on efficiency,” he said. “How can we do things differently with the limited resources that we have?”

The garden will remain open to the public on a daily basis and continue its schedule of public and industry open houses throughout the year. Those seeking more information about the garden can visit

(Merritt Melancon is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.)

New legal residency requirement for pesticide licenses

During the last state legislative session, a house bill was passed that required all state agencies that issue licenses to verify the legal residence of the applicant. All state agencies had to comply. The following explains the process required for verifying your legal residency when applying for a pesticide license renewal with the Georgia Department of Agriculture.

The following link contains the S&V (Secure & Verifiable) affidavit that you must submit when you renew your GA Dept of Ag Commercial Pesticide License

•             Go to the documents column on the right side of the page.

•             Click on the Affidavit link at the bottom of the column.

•             Complete the form and have it notarized. Include a copy of  the applicant’s ID.

•             Mail, fax, or e-mail the form to the Licensing Division.

This document must accompany all new private and commercial pesticide licenses as well as renewals. It is important to understand that you will only have to complete this process once. The Affidavit will be kept on file with the GDA Licensing Program.

The website also has a tutorial to lead you through the online license renewal process.

Without the Secure and Verifiable Affidavit, new licenses and license renewals cannot be processed. If you have any questions call the Licensing Division (855) 424-4367. If the Department of Agriculture can provide additional information, please let us know.