Fall Interseeding and Overseeding: Not One and the Same

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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.

Emerald Ash Borer found with a foothold in North Georgia

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EAB Debbie Miller, USDA Forest Service
Emerald Ash Borer, Debbie Miller, USDA Forest Service, Bugwood.org

Sandi Martin and Merritt Melancon,  University of Georgia 

For years foresters and invasive insect experts have been on the lookout for the arrival of an unwelcome guest in Georgia. Now that it’s here, they hope the public will help restrict its spread within Georgia.

The small, iridescent-green beetle has killed millions of ash trees across a wide swath of Canada and the upper Midwest since it was first detected in 2002. The emerald ash borer — Agrilus planipennis— has spread south and west from infested areas over the last decade.

In July, researchers found adult emerald ash borers in survey traps in DeKalb and Fulton counties. A follow-up ground survey found larvae in nearby ash trees, confirming an established emerald ash borer infestation.

EAB larvae David Cappaert, Michigan State University
Emerald Ash Borer larvae in tree, David Cappaert, Michigan State University, Bugwood.org

Since 2005 University of Georgia invasive species experts have conducted an extensive trapping program in Georgia to screen for the emerald ash borer.

Georgia’s five species of native ash trees usually grow along stream banks. While ash only makes up about 1 percent of Georgia forests, they play an integral role in preventing the erosion of stream banks and keeping silt out of natural waterways. Ash is also a popular landscape tree, with 2.9 million trees planted around Georgia homes, businesses, parks and greenways. The value of these city trees in Georgia is estimated to be around $725 million.

EAB exit hole Penn. Dept. of Conservation & Natural Resources - Forestry Archive
Emerald Ash borer creates a D-shaped exit hole, Image from Penn. Dept. of Conservation & Natural Resources – Forestry Archive, Bugwood.rog

Although the adult beetle is an active flyer, it is believed that the primary way the beetle spreads is by hitching a ride on infested ash firewood, logs and nursery stock. Emerald ash borer larvae kill ash trees by burrowing serpentine tunnels in the inner layers of bark, preventing the tree from transporting water and nutrients to and from the tree canopy.

The Georgia Invasive Species Task Force will launch a public outreach plan to try to curb the spread of this pest in the near future. This task force consists of the Georgia Department of Agriculture, the Georgia Forestry Commission, UGA, the Georgia Department of Natural Resources and the USDA Animal and Plant Health Inspection Service.

People can help slow the spread of this beetle through Georgia by not moving firewood and by helping others to understand how dangerous it can be to move firewood from one area to another.

“To prevent the spread of emerald ash borer, it is important not to move firewood in which the insect can hide,” said Kamal Gandhi, associate professor in the UGA Warnell School of Forestry and Natural Resources. “Buy local firewood, whether camping or for your home.”

To help reduce the spread of the emerald ash borer in Georgia, homeowners with ash trees should have a certified arborist check their trees for signs of emerald ash borer infestations.

Suspected infestations should be reported immediately so that foresters or arborists can understand how the infestation is spreading. This will aid in the development of effective methods to reduce its spread and impact.

“The faster (scientists) can track the spread of the insect, the faster they can work to stop it,” said Joe LaForest, integrated pest management and forest health coordinator at the UGA Center for Invasive Species and Ecosystem Health.

The public can report suspected infestations by:

For more information about the emerald ash borer and how to protect ash trees, visit www.gainvasives.org/eab.

For more information about spotting signs of emerald ash borer infestations, watch this.

(Sandi Martin is the public relations coordinator with the University of Georgia Warnell School of Forestry and Natural Resources. Merritt Melancon is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.)

Other information:

Emerald ash borer factsheet

Emerald Ash Borer 2013 Update

Frequently asked questions about EAB in Georgia

Destructive tree pest discovered in Georgia

New bee advisory on neonicotinoid pesticides

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See original article from the Southern Region IPM News here

In an ongoing effort to protect bees and other pollinators, the U.S. Environmental Protection Agency (EPA) has developed new pesticide labels that prohibit use of some neonicotinoid pesticide products where bees are present. (This announcement affects products containing the neonicotinoids imidacloprid, dinotefuran, clothianidin and thiamethoxam. – Editor’s note)

“Multiple factors play a role in bee colony declines, including pesticides. The Environmental Protection Agency is taking action to protect bees from pesticide exposure and these label changes will further our efforts,” said Jim Jones, assistant administrator for the Office of Chemical Safety and Pollution Prevention.

Bee advisory box from EPAThe new labels will have a bee advisory box and icon with information on routes of exposure and spray drift precautions. Today’s announcement affects products containing the neonicotinoids imidacloprid, dinotefuran, clothianidin and thiamethoxam. The EPA will work with pesticide manufacturers to change labels so that they will meet the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) safety standard.

In May, the U.S. Department of Agriculture (USDA) and EPA released a comprehensive scientific report on honey bee health, showing scientific consensus that there are a complex set of stressors associated with honey bee declines, including loss of habitat, parasites and disease, genetics, poor nutrition and pesticide exposure.

The agency continues to work with beekeepers, growers, pesticide applicators, pesticide and seed companies, and federal and state agencies to reduce pesticide drift dust and advance best management practices. The EPA recently released new enforcement guidance to federal, state and tribal enforcement officials to enhance investigations of beekill incidents.

More on the EPA’s label changes and pollinator protection efforts: http://www.epa.gov/opp00001/ecosystem/pollinator/index.html

View the infographic on EPA’s new bee advisory box: http://www.epa.gov/pesticides/ecosystem/pollinator/bee-label-info-graphic.pdf

Largest Mushroom Species in the Western Hemisphere Found Growing in Georgia

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Jeff DeLong, Undergraduate Researcher, Department of Plant Pathology
Marin Talbot Brewer, Assistant Professor, Department of Plant Pathology

See the original article here

Mushrooms from clusters of M. titans
Mushrooms from clusters of M. titans

Macrocybe titans is the largest gilled mushroom of any species in the Western Hemisphere, with caps in excess of 100 cm (3 ft). These giant mushrooms often occur in clusters within the tropics and subtropics of the New World, with previous sightings reported in the Caribbean, Central America, Mexico, South America, and only in Florida within the USA. Confirmation of this species in Georgia now extends the previously known range of M. titans. To our knowledge, this is the first report in Georgia. The mushrooms were discovered in October 2012 in the yard of an abandoned house in Athens. The fungus was identified as M. titans based on morphological features, habitat where it was found and DNA sequence similarity with known specimens.

The large, cream to buff-colored mushrooms were found growing in three large, dense clusters of eight to 10 mushrooms each (Figure 1). Single caps were 20-30 cm (8-12 in) across and convex with incurving at the margin. Younger mushrooms (Figure 2) had more convex caps than those of older specimens that became flattened with age. The smooth, dry surfaces of the caps were cinnamon-buff in color at the crowns fading to cream toward the margins. The inner flesh of the caps was white. The spore print, which was obtained by placing a cap on half white and half dark-colored paper and covering it with a bowl overnight, was creamy white (spore prints are necessary for proper mushroom species identification).

The stipes (stems) of the mushrooms were cream to buff measuring 30-45 cm (12-18 in) in length (Figure 3). They were club-shaped, tough and fibrous with bent-back scales and striations that curved around the stipe like stripes on a candy cane. The dense clusters of mushrooms were formed by the attachment of individual stipes at the base. Several miniature mushrooms less than 2.5 cm (1 in) in height were found attached to the base of the clusters. The cream to dull-yellow gills of the mushrooms were wavy, crowded and attached to the stipes. The species of the mushroom-producing fungus was confirmed as M. titans by sequencing a region of its DNA.

The mushrooms of M. titans, like the fruiting bodies of any fungus, are the reproductive structures where the spores are produced. The majority of the fungus is actually growing as filamentous hyphae underground and out of sight in decomposing dead and decaying plant matter in the soil. The three nearby clusters that were observed likely came from a single individual growing in the soil beneath the tall grass. M. titans is saprotrophic, which means that it decomposes dead or decaying plant matter and does not cause disease or rot on living grasses or trees.

It is not clear why or how this fungus found its way into Georgia. The mushrooms were close to landscape ornamental grasses and it may have arrived with the container plants, as Florida is a large producer of ornamental landscape plants. Or, it may be expanding its geographic range into Georgia due to climate warming or some other factor. This species was previously known as Tricholoma titans, but in 1998 was renamed Macrocybe titans, which literally translates from Latin into “giant large head.” The mushrooms are reportedly edible; however, never consume a wild mushroom without identification confirmation by an expert. Contact your county Extension office should you happen to encounter the giant mushrooms of M. titans.

We thank Kirk Edwards for discovering these mushrooms and contacting us about their identification.

References:

Bessette, A.E., Roody, W.C., Bessette, A.R., and Dunaway, D.L. 2007. Mushrooms of the Southeastern United States. Syracuse University Press, Syracuse, NY.

Bigelow, H.E., and J.W. Kimbrough. 1980. Tricholoma titans, a new species from Florida. Mycotaxon 11: 425- 429.

Pegler, D.N., Lodge, D.J., Nakasone, K.K. 1998. The pantropic genus Macrocybe gen. nov. Mycologia 90: 494-504.

Wood decay and falling trees are of great concern

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Jean Williams-Woodward, UGA Extension Plant Pathologist

Damage from past years of drought has taken a toll on our trees. Drought stress, construction injury, soil compaction and root girdling injures tree roots and provides an entry point for wood decay fungi. Storm damage, improper pruning, and wounding of trunks and branches also leads to wood decay fungi entry and infection.

Wood decay fungi can be classified into two broad categories: white-rot and brown-rot fungi.

White-rotters are those fungi that rapidly breakdown lignin and eventually cellulose. The infected wood becomes soft, spongy and stringy. It is usually a root and butt rot by a white-rot fungus that causes hardwood trees to fail and fall (see images of Inonotus dryadeus).

Brown-rotters are those fungi that breakdown cellulose and eventually lignin. Wood crumbles and shrinks. These rots are often referred to as a cubical or dry rot.

Regardless of the type of rot and what fungus is infecting the tree, if you see conks or mushrooms growing on the tree trunk or root flare, then the tree is in advanced stages of infection and decay and there is a concern for possible tree failure. It takes years for infection and growth of the fungus in the wood to produce outward signs of conks and mushrooms.

At present, methods to accurately detect how much rot is present in the wood do not exist. There are methods to detect internal cavities in trees to determine the thickness of a trunk shell, but measurements of spongy wood is difficult. There is no cure for wood decay. The best management approach is preventing injury to trunks, branches, and roots.

Mosquito season continues through September

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Elmer Gray, UGA Extension Entomologist

As we move into the last weeks of summer, be aware of the excellent conditions for mosquito development that this summer’s heavy rains have created. This year has been very different from recent years when we consider our local rainfall totals. To date, much of the state is 15 inches or more ahead of normal rainfall for this time of the year. As a result there is more standing water in our counties and communities than in recent memory. This standing water will provide excellent larval habitat for mosquitoes as we move into the last few weeks of summer.

Mosquitoes are semi-aquatic insects that require standing water for the larval and pupal stages. There are 63 species of mosquitoes

Mosquito life cycle
Mosquito life cycle, Art Cushman, USDA Systematics Entomology Laboratory, Bugwood.org

known in Georgia and as result they exhibit a range of life histories.

Typically, the female mosquito will lay eggs on the surface of the water, attached to the sides of a container just above the water’s surface or on moist soil that will become covered with water at a later date. After being covered with water and in due time, the eggs hatch and the larvae (or “wigglers” as they are commonly called) develop in the standing water. The larvae are filter feeders, feeding on small particles of plant and animal matter.

After developing through 4 instars the larvae progress to the pupal stage which is commonly called a “tumbler” due to their movement through the water. Both the larvae and pupae come to the water’s surface for air and move down into the water when disturbed. After 2-3 days in the pupal stage the adult mosquito that we are all familiar with will emerge onto the water’s surface.

In the late summer, this cycle can be completed in as little as 7 days. This summer, with the numerous cloudy days and relatively cool temperatures, this cycle has surely been extended. The cool night temperatures have probably been the only thing preventing even worse mosquito populations than we have already experienced.

Homeowners can often reduce mosquito populations around their homes and neighborhoods by being diligent. All standing water should be eliminated or treated with an EPA approved larvicide if mosquito larvae are present. Emptying buckets, plant saucers, boats, tarps and anything else that can hold water is extremely helpful. Keeping gutter’s clear of leaves and debris will help to eliminate the often neglected larval habitat of backed up gutters. Homeowners should also check those rain barrels that were so helpful in past year’s droughts. It is vital that screens are intact around all openings or these barrels will become highly productive mosquito habitats. In addition, screens on the windows and doors should be checked to make sure there are no holes. Many mosquitoes are attracted to light and will be drawn to open windows after dark when we’re trying to get some fresh air in our homes.

As of August 22, the Georgia Department of Public Health has only reported 2 human cases of West Nile virus (WNV) in Georgia. This low number of cases is in contrast to last year when Georgia experienced a record 117 cases of WNV with 6 deaths. The WNV is now known to occur across the state and has been isolated from mosquitoes in the four counties (Chatham, DeKalb, Glynn and Lowndes) where adult mosquito surveillance and testing are being conducted this year.

The low number of human WNV cases is likely related to the fact that the mosquito (the Southern House Mosquito) that transmits the disease often develops in the storm drain system, particularly during dry periods. With this year’s heavy and regular rainfall, the storm drain systems across the state are regularly flushed and populations of this mosquito have been somewhat suppressed. However, we don’t want people to let down their guard as football season arrives. The peak period for WNV transmission in Georgia has historically been August 15-September 15. The proper use of EPA approved repellents is highly recommended if people are expecting to encounter mosquito populations in the next few weeks.

Products containing DEET are recommended for use on children as young as two months by the American Academy of Pediatrics. Parents should apply the repellent to their hands and then apply it to the children. It is important to get good coverage and then wash the treated skin upon returning indoors.

In conclusion, mosquito control districts across the state are reporting high numbers of complaints due to a variety of species of mosquitoes that have benefited from the abundant rainfall. Health districts across south Georgia are also seeing an increase in Eastern Equine Encephalitis (EEE) in horses. This disease is caused by a virus that is transmitted by mosquitoes that typically develop in the swamps and woodlands below the fall line in Georgia. While cases are rare in humans, EEE symptoms range from mild flu-like illness to encephalitis (inflammation of the brain), coma and possibly death. Symptomatic cases have a fatality rate of 30-50% and it is classified as the most severe mosquito-borne disease of humans in the United States.

Preventing mosquito bites is crucial to avoiding any of the mosquito-borne diseases. Loose fitting, light colored clothing, coupled with the proper use of EPA labeled repellents, will go a long ways towards this goal by making us less attractive to mosquitoes.

 

For more information

Stinging and Biting Pests

Management of Pest Insects in and Around the Home

Georgia Mosquito Control Association

Forest Pest Insects in North America: a Photographic Guide

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R. G. Van Driesche1, J. LaForest2, C. Bargeron2, R. Reardon3 and M. Herlihy1

1University of Massachusetts, PSIS/Entomology; 2University of Georgia; 3USDA Forest Service, State and Private Forestry

Orangestriped oakworm, Lacy L. Hyche, Auburn University, Bugwood
Orangestriped oakworm, Lacy L. Hyche, Auburn University, Bugwood

The photos present in this publication are intended to help foresters, urban landscaping employees, or others working with trees recognize some of the common pest insects affecting trees in North America and understand their life cycles and how they damage trees.

Read more

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

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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.

Preemergence Herbicides for Annual Bluegrass

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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, Bugwood.org

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)

Control
Clethodim Envoy

E
Fenoxaprop Acclaim Extra

E
Mesotrione Tenacity

F-G
Quinclorac Drive, Drive XLR8

E
Sethoxydim Segment, others

E

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)

Control
Atrazine Aatrex, others

E
Benefin Balan

E
Bensulide Betasan, others

F
Dithiopyr Dimension

G
Ethofumesate Prograss

G-E
Mesotrione Tenacity

F
Oryzalin Harrier, Surflan

G
Oxadiazon Ronstar, Starfighter

G
Pendimethalin Pendulum, others

G
Prodiamine Barricade, Cavalcade, others

E
Pronamide Kerb

E
Simazine Princep, WynStar, others

E

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.

Topics:

 

Annual Bluegrass Control in Non-Residential Commercial Turfgrass

Patrick McCullough, UGA Department of Crop and Soil Science

Accessible Training for the Landscape & Turf Industries

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Online training

The Safety Makes Sense: Landscape Worker Safety Certificate Course is available at no charge on Vimeo (vimeo.com/46623806).  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 – http://about.extension.org/

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 https://learn.extension.org/

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 www.elearn.sref.info

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

To access the modules for volunteer credit or a certificate of completion, visit www.campus.extension.org  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 sashton@sref.info .

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.

Certification

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 ebauske@uga.edu.

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

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.

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