cogongrass-conference-proceedings

The answers to the following questions are contained in this ”Proceedings of the Regional Cogongrass Conference”, and should aid us in confronting the cogongrass crisis across the South:

Proceedings of the Regional Cogongrass Conference:

Mobile, Alabama

Cogongrass Management Guide

Conference Co-Chairs

James H Miller USDA Forest Service R&DNancy J LoewensteinAuburn University School of Forestry and Wildlife Sciences

andAlabama Cooperative Extension System

Silver

Alabama PowerAuburn Center for Forest SustainabilityAuburn School of Forestry and Wildlife SciencesBaldwin County (Alabama) Soil and Water Conservation District

National Council for Air and Steam Improvement (NCASI)

National Park Service

Bronze

BASFLee County (Alabama) Soil and Water Conservation District

We sincerely thank the following vendors and exhibitors for supporting this

conference:

Vendors

BASFCoosa Trading Company (Eric Prater, vendor coordinator)

DOWHelena ChemicalNufarm ChemicalUAP Distribution, Inc

Exhibitors

Alabama Invasive Plant CouncilFlorida A&M UniversityMississippi Exotic Pest Plant Council

Mississippi USDA

Mississippi State University GeoResources Institute

Tennessee Exotic Pest Plant Council

IntroductionThis Regional Cogongrass Conference was organized because of the deep concernsexpressed by many over the unrelenting invasion of this bold, unwanted, and hard-to-controlgrass, this cogongrass Even though many seem acquiescent to the spread of kudzu, privets,

or honeysuckle, the takeover by cogongrass drives well deserved fears and dire predictions

by land users, owners, and conservationists alike Its occupation is so tight and completethat it excludes even other invasive plants, and certainly most wildlife, insects, and micro-fauna and flora It does not just alter the web-of-life, it replaces it with a lime-greenbiological desert It completes its domination by burning so intense that it consumes anyand everything to below 10 feet high, whether native shrubs or human structures, tothreaten the lives of firefighters Throughout the World, on every continent exceptAntarctica, its notoriety as the “Worst Invasive Plant of Non-crop Lands” is well-earned since

it exacts huge tributes and enacts lasting changes on cultures that live close to the land,and our southern culture actually lives close to the land but few remember this We livefrom the land still in both sustenance and spirit, since we have been blessed to inhabit one

of the richest land-plant-soil systems remaining on the planet Few other countries can evenremember such a time in their recent history, their time is long past, but we live in such atime now How long will this last?

Only recently have we learned that major civilizations throughout history have

“perished” when they neglected or overused their productive land base, or when climate

change had it in for them (see Jarred Diamond’s Collapse) From the current vantage point it

might appear that both of these factors are at work now unrelenting occupation bycogongrass and other invasives that stop productivity and the warming and drying of ourregion Both factors challenge our resolution and creativity to JUST recognize the problems inenough time, confront the problems, organize and arm ourselves, and enact well-devisedsolutions, or at least attempt solutions There is one other common trait that “perished”civilizations shared that now harkens to us; their leaders failed to understand the real land-soil-plant crises, pointed to other less severe problems as the culprit, and did not leadneeded proactive programs and life-style modifications Most of these past demises werethought to be insurmountable changes underway caused by demon spirits We arehopefully not that ignorant now and know better Ameri-CANS know we CAN do theimprobable and have done it before given that we are organized, trained, empowered, andleft to apply our collective and individual initatives We can stop cogongrass, if we so desire,there is no doubt Not withstanding that facing a common foe for the common good is not invogue, since self interests appear to rule the day

This conference will hopefully will play a pivotal role in changing our predicament bydetailing the problem due to cogongrass, the circumstances that hinder right action, and thedirection we should collectively take armed with the knowledge that we have gained Many

of the experts on cogongrass from impacted states in our region willingly gathered to sharetheir knowledge at this Conference and provided carefully written instructions that form thispreliminary draft of “The Cogongrass Management Guide”, which now you have in yourhands We are exceedingly grateful to them for their dedication of time and energy Theseexperts are both knowledgeable and form the frontlines for combating cogongrass in theirstates and do it on a regular and persistent schedule It is not easy to confront this invasion

at this time in our history Dr Ray Dickens, Auburn University, was first to stand up in the1970’s and boldly state that we must stop cogongrass now or we will regret otherwise Hewas right, but unfortunately ignored Others have followed him and done their best tocombat cogongrass, like Art Miller in Georgia during the 1990’s Now we must say it louder,together, and to our citizens and leaders, “We must stop this invasion of cogongrass.” Wemust stop the spread eventhough it is like fighting a huge creeping wildfire that is spotting

and like attempting to slow a locomotive heading towards us and gaining speed We cannotstop saying “Stop the Spread” and killing cogongrass where we find it, because if we do notstop it in the South, it will consume much of lands and spread throughout the Eastern andnorthwestern U.S We are on the frontlines It is our responsibility, not others There is noother time, but now, and no place to hide from the future blame of yet unseen generationssaying “we wasted our precious lands and land resources by relenting to this tyrant grass….that they now have to live with and make a living from and raise our children in a degradedlandscape”, much like the rest of the whole does today JHM

Regional Cogongrass Conference:

Confronting the Cogongrass Crisis Across the

South

November 71-1:30 Welcome, Introductions and Conference Objectives

pg

The Context of the South’s Cogongrass Crisis

6

Dr Jim Miller, U.S Forest Service R&D

1:30-2 Cogongrass (Imperata cylindrica): The Plant’s Biology,

10

Distribution, and Impacts in the Southeastern US

Dr Greg MacDonald, University of Florida

2-2:30 Cogongrass Distribution and Spread Prevention

24

Dr Dave Moorhead, The University of Georgia

2:30-3 What Works on Cogongrass and What Does Not: A Summary of

28

nearly 10 years of Cogongrass Research in Mississippi

Dr John Byrd, Mississippi State University

3-3:30 Break and Visit with Vendors

3:30-4 Cogongrass in Pastures and Hay-Meadows in Louisiana: A Historical

32

Perspective and Control Recommendations

Dr Dearl Sanders, Louisiana State University AgCenter

4-4:30 Managing Cogongrass on Rights-of-way: a challenge to prevent

34

future spread

Dr Wilson Faircloth, USDA Agricultural Research Service

4:30-5 Operational Considerations for Control of Cogongrass

38

Lee Atkins, Progressive Solutions

Mobile Convention Center Mobile, Alabama

5-5:30 Questions and Comments, Dr Dave Moorhead moderating

5:30-8 Social and Vendors

November 8 8:00-8:30 What Research has found about Establishing Loblolly Pines in

43

Cogongrass Infestations

Dr Jim Miller, US Forest Service R&D

8:30-9:00 What Research Has Found about Cogongrass Spread and Control

48

in the Longleaf Pine Ecosystem

Dr Shibu Jose, University of Florida

9:00-9:20 What a Forest Practitioner Has Learned by Developing an

51

Operational Program for Cogongrass Management

George Robertson, Scotch Lumber Company Inc

9:20-9:40 What a Right-of-way Manager has learned during Operational

54

Treatments

Howard Peavey, Alabama Department of Transportation

9:40-10 How to Organize and Perform a Right-of-way Program with Partners

55

Chris Bryan, Mississippi Department of Transportation

10-10:30 Break and Vendors

10:30-11 Cost-share, Incentive and Grant Programs Currently Available to

57 Combat Cogongrass

Dr John Taylor, USDA Forest Service State & Private Forestry

11-11:20 How Can We Organize Ourselves at the County Level to be Effective

58

at Combating Cogongrass

Linda Conway Duever, Conway Conservation LLC

11:20-11:40 Georgia’s Cogongrass Efforts: How One State Organized to be

63 Effective in Combating Cogongrass

James Johnson, Georgia Forestry Commission

11:40-12 What We Have Learned and What We Need To Do Next

69

Dr Jim Miller, USDA Forest Service R&D

12-12:30 Move to buses in front, take a box lunch and drink.

Buses will shuttle participants between sites at 3 pm; with half at each site

12:30-5 Field Tour

Stop 1 Muddy Creek Restoration Site:

• Restoration underway for cogongrass to longleaf pine stand

• Treatment demonstration

o Gena Todia, Wetland Resources Environmental Consulting

o Jason Saucier, Wetland Resources Environmental Consulting

o Fred Nation, Fred Nation Environmental Services

o J.J McCool, Wildlife Solutions, Inc.

Stop 2 DeGussa Research Site:

74

• Cogongrass identification

• Loblolly pine establishment in a dense cogongrass infestation using combinations of herbicide and trenching site preparation and various

overtop herbicide mixtures in combinations with pines in the 6 th growing season.

o Wilson Faircloth, USDA ARS

o Mike Patterson, Agronomy Extension, Auburn University

o Jim Miller, USDA Forest Service R&D

The Context of the South’s Cogongrass Crisis

James H Miller, Ecologist, U.S Forest Service R&D

Auburn University, Alabama

Cogongrass is a world-class weed that is invading the South The southern region is

in a crisis Cogongrass (Imperata cylindria) is a world-class invasive grass and a

Federally-listed noxious weed that continues to invade more lands and is widely regarded as the worstinvasive threat in the Southern U.S Since its multiple introductions in the early 20th century,

it has spread to infest 1 million acres in Florida and tens of thousands of acres in Alabama,Georgia, Louisiana, Mississippi, South Carolina and Texas Annual spread rates are estimated

in the thousands of acres and its tolerance to shade means that infested acreage includesinterior forests Between 1952 and 1974, cogongrass invaded 850 acres per year in MobileCounty to occupy 10,000 acres by 1974 Short distant spread by windblown seed and longdistant spread by movement of contaminated pinestraw, vehicles and rhizomes in fill dirtmeans entry to Tennessee, North Carolina, and Arkansas is imminent Most of the EasternU.S and Pacific Northwest states are considered vulnerable The outcome of cogongrassoccupation on other continents has been devastating and this same trend is underway in theSouth where cogongrass can eventually cover most uncultivated lands It will not magicallydisappear someday without concerted programs to contain and combat it The contributions

of dedicated experts to this conference’s proceedings should help us all

It is an era of rapid environmental and ecological change.

The invasion of cogongrass appears facilitated by dynamics in this era of rapid globalwarming, increased air pollution with higher carbon dioxide levels, human encroachmentwith wildland fragmentation, and solidifying urbanization with a population indifferent to theland base that supports them These conditions favor cogongrass invasions However, awider understanding of this problem should lead to more problem recognition, unifiedprograms with laws, policies, and funding to counter this invasion

The answers to the following questions are contained in this ”Proceedings of the Regional Cogongrass Conference”, and should aid us in confronting the cogongrass crisis across the South:

• What makes cogongrass so invasive and difficult to control?

• Where are current infestations, where is cogongrass heading and how can

we prevent the spread?

• What are the most effective integrated treatments and management regimens for forestry, preserves, pastures, and rights-of-ways? What information are we lacking?

• What is the value of burning and mechanical treatments when used with herbicide applications?

• How can herbicides be selected and applied to be most effective (herbicides, decoding generic formulations, timing, mixing ingredients, and application systems)?

• What have researchers found by comparing alternative treatments for rehabilitation and restoration?

• What have practitioners learned during operational treatments?

• What cost-share, incentive, and State programs are currently available?

• How can we organize ourselves and build cooperative programs at the local, county, state, and regional levels?

Cogongrass forms the most exclusive infestations of all invasive species.

Productivity losses to forestry, pasture, and orchards are evident but yet to be documented,while control costs are mounting across land uses, including rights-of-way andmunicipalities Vast displacement of native plants and wildlife is underway, and isexasperated by the extreme flammability of the grass This siege to our lands and theirrichness and productivity cannot be tolerated without a concerted attempt to stop itsspread, and reclaim and secure the future of our lands from this and other invasive species.The insights that follow in this publication, by some of our most expert scientists andmanagers, should aid us greatly in devising strategies, policies, and networks to contain thespread and restore infested lands

Cogongrass Impacts

• Stops or hampers productive use of forest lands, pastures, pecan and other orchards, impacts container crops and right-of-way management and is invading municipalities

• Is highly flammable and presents a high risk to rural homeowners and firefighters.

• Wildlife habitat is destroyed and hunting privileges denied

• Recreational value is nonexistent and the natural beauty of our lands is defaced.

• Reduces native species biodiversity, impacts community and ecosystem functions and interferes with ecosystem services.

• Eradication costs vary but exceed $200 per acre and can range much higher

Cogongrass is part of a BIGGER INVASION in the South that demands both a separate and unified management program The many major seaports around the Gulf

coast combined with a long period of horticultural introductions throughout the region haveresulted in multiple plant invasions underway in concert with the cogongrass spread

Tallowtree (Triadica sebifera) is spreading upward from the Gulf Coast, from an epicenter

near Houston, TX, to currently occupy over 600,000 acres Japanese climbing fern

(Lygodium japonicum) is spreading outward from the coast by spores in wind and

contaminated pinestraw and equipment to infest over 200,000 acres Tropical soda apple

(Solanum viarum) was introduced in Florida in the 1990’s and now occupies over 200,000

acres and is spreading rapidly by cattle transport and wildlife Japanese honeysuckle

(Lonicera japonica) and Chinese privet (Ligustrum sinense) are both at pandemic levels

across the South exacerbating all control and restoration efforts dealing with cogongrass

Although there is “one invasion of cogongrass” impacting the region, each State differs greatly in their laws, management efforts, and funding

Unified Program Goals for all States should be to:

• Prevent the northward spread and spread into adjoining States.

• Contain the spread of the advancing front within States.

• Save special habitats and preserves from degradation.

• Restore infested lands to a productive status to include diverse biology

This means that Invasive Management Plans are needed in every State, which

includes adaptive management cycles of learning and sharing advancements inunderstanding to all stakeholders All actions and strategies must work through collaborativenetworks across fragmented landscapes with the aim to constrain invasions and restore eco-services I have termed this process “Adaptive Collaborative Restoration” “Adaptive” since

we are learning as we go, “collaborative” since we must be connected with adjacent landsand managers, and “restoration”, since our aim is to sustain and restore healthy food andfiber production systems as well as the wildlife habitat and recreation value associated withthese lands

The Program Elements of an Invasive Adaptive Collaborative Restoration Program are:

• Cooperative networks among stakeholders and partners at the regional, state, multi-county and county levels.

• Spread prevention strategies and programs through improved laws, policies, and public education; along with promoting new responsibilities such as not planting invasive plants and sanitizing equipment and personnel when moving among infested sites.

• A network for Early Detection and Rapid Response (EDRR) to identify and locate new high risk introductions, communicate and verify the sites, and eradicate the outlier infestations

• Survey and Mapping of existing and spreading invasions to identify areas of high infestations, advancing fronts, and outliers with real-time displays that are web accessible.

• Coordinated control, containment, and eradication through repeated integrated vegetation management treatments along with monitoring and conveying results.

• Focused research with rapid technology transfer through effective networks.

Cogongrass is a “problem of the commons” and we all are impacted and must help

There have been a few examples of concerted and focused efforts to contain cogongrass inthe region There was an effective eradication program in Georgia by the State APHISCoordinator, Arthur Miller, in the 90’s Georgia is again organizing to carry on eradication.Dearl Sanders in Louisiana has directed a State effort for a decade to combat cogongrass inhis State Florida’s Environmental Protection Agency’s Bureau of Invasive PlantManagement uses State appropriated funds through an organized program for invasive plantcontrol on “preserve lands”, including cogongrass None have been strong enough to stopthe persistent spread within any state or across state lines Presently, grass-rootCogongrass Task Forces are being formed in Georgia, Mississippi, South Carolina, andLouisiana Still, little State political recognition or leadership has been applied to theproblem and funding of programs is lacking

Tools of Integrated Vegetation Management (IVM)

• Prescribed fire

• Mechanical

• Herbicides

• Biological Control

• Cultural treatments with planting other species

These are the tools that must be sharpened and refined to combat cogongrass on the land

At each level of engagement with the cogongrass dilemma we must collectively determine:

• What are our GOALs and desired outcomes?

• What do we need to know to be successful to reach those goals?

• What do we need organizationally and physically to be successful?

• What is the most “valuable resource” that we want to protect (prioritization)?

• What must we do right to succeed? (What is critical?)

• What role will government play at the various levels?

• What roles must private landowners, industry, and citizens play to be successful?

Cogongrass (Imperata cylindrica) : Biology,

Distribution and Impacts in the Southeastern U.S.

Gregory E MacDonald Department of Agronomy, Institute of Food and Agricultural Sciences,

University of Florida

Biology

Cogongrass is a warm-season perennial grass species found throughout the tropical andsubtropical regions of the world (Holm et al., 1977) It produces extensive rhizomes whichallow it to spread and dominate a wide range of disturbed sites (Holm et al., 1977; Brook,1989) In addition to rhizome production, cogongrass invades and persists through: 1)adaptation to poor soils and drought, 2) prolific wind disseminated seed, and 3) the ability towithstand and thrive in a fire-based ecosystem (Hubbard et al., 1944; Holm et al., 1977;Brook, 1989; Dozier et al., 1998)

Cogongrass leaves grow directly from creeping underground rhizomes, giving the plant astem-less appearance (Holm et al., 1977; Bryson and Carter, 1993) The leaves possesssmooth or sometimes hairy sheaths, with a membranous ligule The leaves are slender, flatand possess serrated margins and an off-center prominent white mid-rib (Hall, 1978; Holm

et al., 1977; Terry et al., 1997) The serrated margins of the leaves accumulate silicates,which deter grazing (Dozier et al., 1998) The leaves can reach 4 to 5 feet in height underconditions of good moisture and fertility (Holm et al., 1977)

Cogongrass rhizomes can comprise over 60% of the total plant biomass and this low shoot

to root/rhizome ratio contributes to its rapid regrowth after burning or cutting (Sajise, 1976).Cogongrass rhizomes are white and tough with shortened internodes Rhizomes are coveredwith brownish colored cataphylls (scale leaves), which form a protective sheath around therhizome (Ayeni, 1985; English, 1998) The formation of rhizomes occurs within 3 to 6 weeks

of initial growth, depending on whether the plant is regenerating from a seed or rhizomefragment Soerjani (1970) estimated cogongrass rhizome production and calculated thatover 2 million shoots could be present per acre More recent research by Terry et al (1997)suggests fresh weights of rhizomes as high as 40 tons per hectare; this providing atremendous amount of biomass for regeneration after foliar loss

Gaffney (1996) observed apical dominance in cogongrass rhizomes, where the shoot tip will sprout, but other shoots along the rhizome remain unsprouted because the shoot tips

produce hormones (auxins) that keep the subtending shoots from sprouting English (1998) induced axillary buds along cogongrass rhizomes with exogenous applications of synthetic auxins, further supporting the role of auxin-regulated apical dominance

Cogongrass is also a prolific seed producer, with over 3000 seeds per plant Cogongrassproduces a shortly-branched, compacted and dense seedhead The seedhead is cylindricaland spike-like averaging 10 to 20 cm long, with fluffy, white plumes Flowering time ishighly variable depending on region and environment In the U.S., flowering generallyoccurs in the late winter/early spring (Shilling et al., 1997; Willard, 1988); but disturbances

such as burning, mowing, grazing, frost or the addition of nitrogen can also stimulateflowering (Holm et al., 1977; Soerjani, 1970; Sajise, 1972) The plumed seeds can travellong distances but generally movement is 15 m (Holm et al., 1977) although McDonald et al.(1996) reported greater movement from larger clumps of aggregate seed No dormancymechanisms have been observed in cogongrass seed, and research has shown a rapiddecline in seed viability over time, with a complete loss of viability after one year

The spread of cogongrass through seeds has been debated by several researchers in thesoutheastern U.S Viable seed has been reported in Alabama, Mississippi and parts ofFlorida; although Willard et al in 1990 reported the primary spread in Florida was fromrhizome pieces, either through contaminated fill dirt used in construction or intentionalplantings for forage Previous research has shown that cogongrass is not self-compatibleand must out-cross to produce viable seed Therefore, populations originating fromrhizomes spread clonally until they grow within close proximity to genetically differentpopulations This lack of seed viability within populations has occurred in the regions alongthe Gulf Coast, but not as frequently in peninsular Florida Burnell et al (2003) showed thatcogongrass first-year seed germination from populations in southern Mississippi, U.S wasover 95%

Seedlings tend to emerge in groups and seeds require light for germination Burnell et al.(2004) found germination in seed collected from Mississippi populations occurred from 11 to

43 C with an optimum temperature of 30 C Dozier et al (1998) indicated that seedlingestablishment is favored in areas of limited competition, such as disturbed sites, and furthersuggested that cogongrass seedlings would be unlikely to establish in areas with >75% sodcover However, additional research has shown that cogongrass seed is able to invade andgrow in established native plant communities but that tillage and burning does favorcogongrass establishment Therefore, activities such as natural disasters (e.g., hurricanes)and human disturbance (e.g., logging, road construction) will favor cogongrass spread andestablishment from seeds

Cogongrass is differentiated from the other species of Imperata by the presence of two flower anthers, while other species, including Brazilian satintail (Imperata brasiliensis), have

just one anther (Gabel, 1982; Hitchcock, 1951) However, Hall (1978) did not differentiate

between I cylindrica and I brasiliensis, reporting single populations with both one and two

anthers The variability observed and presence of differing anther number within a singlepopulation suggests potential hybridization between the species (Hall 1998) Molecularcharacterization has been performed, but on a limited scale Therefore, no clear geneticclassification for cogongrass distribution throughout the southern U.S can be made

Another important genetic aspect is the sale of cogongrass var Rubra, or var koenigii Thisvariant is widely promoted as an ornamental grass under the names Rubra, Red Baron andJapanese Blood Grass These varieties have been reported as non-aggressive, but research

by Greenlee (1992) and Bryson (personal communication) suggest that under certainenvironmental conditions these plants revert to the green, invasive form The greatestconcern, however, is the potential for hybridization between ornamental ecotypes andweedy biotypes found in the southern U.S The ornamental varieties have been shown tosurvive as far north as Ann Arbor, Michigan and this could dramatically extend the hostrange of this invasive species Studies by Gabel (1982) and observations by Hall (1998)

which suggest a high degree of variability and potential hybridization within the speciesfurther elevate the importance of this issue

Distribution, Habitats and Impact

Cogongrass is found throughout the world, thriving in areas of natural and particularlyhuman disturbance, and is reported established on over 500 million hectares world-wide(Holm et al., 1977; Dozier et al., 1998) Cogongrass is found along the Mediterranean Sea inEurope and northern Africa to the Middle East It is present in Iran and Afghanistan and

throughout India There are Imperata grasslands in northern India that stretch into Nepal.

Cogongrass is most wide spread in Asia where over 70 million acres are reported as infested(Garrity et al., 1997) It occurs throughout Southeast Asia, Indonesia and the Pacific Islandsand estimates of infestation in Indonesia range from 8.5 million hectares (Garrity et al.,1995) to over 64 million hectares (Suryanta and McIntosh, 1980) These areas possesslarge, solid stands, often called mega-grasslands, Imperata savannas or sheet Imperata.Many of these areas are reported to be greater than 22,000 continuous acres Areas like thisalso occur in Africa, where cogongrass is prevalent in the West African countries, and in theeastern countries of Egypt, Sudan, Ethiopia (Holm et al., 1977) Cogongrass is also found in

western South America while the closely related Brazilian satintail (Imperata brasiliensis

Trin.) is found in central South America Brazilian satintail is also found throughout theCaribbean and south Florida and is often confused with cogongrass

Cogongrass was inadvertently introduced in the U.S (Mobile, Alabama) in 1912 as a packingmaterial in Satsuma oranges from Japan (Tabor, 1949; 1952; Dickens, 1974) Cogongrassfrom the Philippines was purposefully introduced to Mississippi as for forage in 1921, withsubsequent forage trials carried out in Florida, Alabama and Texas, although the Texasplanting died out in the first year (Hubbard et al., 1944; Dickens and Moore, 1974).Cattlemen in Florida interested in cogongrass as a forage acquired the grass in 1939 and by

1949 over 1000 acres had been established in central and northwest Florida (Tabor, 1952;Hall, 1983; Coile and Shilling, 1993) Trials concluded that cogongrass was not anacceptable forage due to poor nitrogen content, poor digestibility and accumulation of silica

in the mature leaf tissue

Cogongrass tolerates a wide range of soil conditions, but appears to grow best in soils withacidic pH, low fertility and low organic matter Habitats infested with cogongrass are quitediverse, ranging from the course sands of shorelines, the fine sands or sandy loam soils ofswamps and river margins, to the >80% clay soils of reclaimed phosphate settling ponds.Saxena and Ramakrishnan (1983) report cogongrass to be extremely efficient in nutrientuptake Brook (1989) also report associations with mycorrhiza, which may help explain itscompetitiveness on unfertile soils Brewer and Cralle (2003) also suggested that cogongrass

is a better competitor for phosphorus than native pine-savanna species in the southern U.S.,citing that legume species are frequently displaced through this competitive mechanism Cogongrass is a C4 grass species (Paul and Elmore, 1984), and while it is best adapted to fullsun, cogongrass can also thrive under moderate shade (Hubbard et al., 1944) Studies byGaffney (1996) and Ramsey et al (2003) showed that cogongrass has a light compensationpoint of 32 to 35 mol.m-2.s-1 (approximately 2% full sunlight) indicating the ability to survive

as an understory species This would explain its ability to both rapidly invade deforestedareas and persist in plantation crops

Cogongrass habitats in the southern U.S are often fire-based ecosystems where excess leafbiomass provides fuel for fires In its native range cogongrass is a pyrogenic species, relying

on fire for survivability and spread (Holm et al., 1977) Cogongrass fires are very intenseand hot, with little above ground vegetation able to survive, limiting natural secondarysuccession (Eussen and Wirjahardja, 1973; Seavoy, 1975; Eussen, 1980; Lippencott 2000).Fires from cogongrass are typically 15 to 20% hotter and more intense than natural fires inpine-based ecosystems in the Southern U.S

Another mechanism by which cogongrass maintains dominance is through allelopathy Cogongrass has been reported to suppress the growth of crops and studies have

demonstrated the potential allelopathy of cogongrass (Eussen, 1979; Casini et al., 1998; Koger and Bryson, 2003) Interference can also be in the form of physical injury; the hard, sharp points of cogongrass rhizomes penetrate the roots, bulbs and tubers of other plants, leading to infection (Boonitee and Ritdhit, 1984; Eussen and Soerjani, 1975; Terry et al., 1997)

Cogongrass invades and persists in moist tropical areas and is considered a primary weedy

species in tea (Camillia sinesis L.), rubber (Hevea spp.), pineapple (Ananas comosus Merr.), coconut (Cocos nucifera L.), oil palm (Elaeis spp.) and other perennial plantation crops in

Asia In Africa it causes the greatest damage in agronomic production (Ivens, 1980) and isconsidered to be the most serious agricultural weed in Benin, Nigeria and southern Guinea,infesting over 20 crop species (Chikoye et al., 2000) Early reports by the InternationalInstitute of Tropical Agriculture (1977) showed 54% of the total crop production budget wascogongrass weeding Chickoye et al (2000) stated farm size in west Africa was limited bythe labor intensiveness of cogongrass and Terry et al (1997) reports that vast areas ofarable land in west Africa has been abandoned due to the lack of effective cogongrasscontrol Cogongrass is occasionally used as a forage crop in underdeveloped countries, butcan only be grazed when the plants are very young Intensive management is needed tomaintain the foliage in the juvenile vegetative stage Cogongrass has also been shown toharbor locusts, and there is evidence that swards of this grass are a major breeding groundfor these pests (Brook, 1989)

In the U.S., cogongrass poses the most serious threat to native ecosystems There are over1,000,000 acres with some level of infestation in Florida alone Several thousand acres arealso infested in the states of Alabama and Mississippi (Bryson and Carter, 1993; Matlack,2002) This species can also be found as far west as Louisiana and as far north as thecoastal regions of Virginia Cogongrass generally invades areas after a disturbance, such asnatural fire or flood or mining/land reclamation, forest operations, highway construction andmaintenance

Once established, cogongrass out-competes native vegetation, forming large solid standswith extremely low species diversity and richness Lippencott (2000) found that cogongrassaltered normal fire cycles of sandhill communities, a natural ecosystem of the southeasternU.S The fires within swards of cogongrass had higher maximum temperatures at greaterheights and increased fire mortality of long-leaf pine, normally a fire tolerant species Theauthor further hypothesized that the changes in fire behavior due to cogongrass invasioncould shift sandhill ecosystems from a species-diverse pine savanna to a cogongrassgrassland Cogongrass is also becoming a major constraint in the forestry industry, invadingand persisting in newly established pine plantations (Jose et al., 2002; Miller, 2000) In

addition, cogongrass poses a major fire hazard along state highways and federal interstatehighways due to excessive smoke and thus limited visibility It also may promote wildfires inresidential communities, especially those near wooded areas

Biocontrol

Literature records suggest a considerable number of potential natural enemies ofcogongrass, including over 80 pathogens, 90 insects, and several nematodes and mitesassociated with cogongrass world-wide (Van Loan et al., 2002) Several researchers have

studied the gall midge (Orsioliella javanica Kieffer), which is reportedly specific to

cogongrass (Soerjani, 1970; Mangoendiharjo, 1980; 1986) This insect destroys shootmeristems, but only after the foliage is cut and the rhizome system debilitated Thisrequirement, along with natural enemies of the midge, significantly reduces the potential ofthis control option Recent research by Yandoc et al (1999) has shown cogongrass in the

U.S is susceptible to infection with two fungal pathogens, Bipolaris sacchari (E Butler) Shoem and Drechslera gigantea (Heald & F.A Wolf) Subsequent studies utilizing these

pathogens as bioherbicides report good foliage control, but limited activity on rhizomes(MacDonald et al., 2001; Yandoc, 2001) Although several organisms have been found andtested, several researchers state that there is little hope of finding a successful biologicalcontrol for cogongrass (Ivens, 1980; Brook, 1989) They claim the distribution of this species

is so world-wide that the chances of finding a novel biological control agent in an area wherecogongrass does not exist are slight

References and Literature Cited

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Cogongrass Distribution and Spread Prevention

Dr David J Moorhead, Professor of Silviculture Warnell School of Forestry & Natural Resources

&

Charles T Bargeron, Technology Coordinator and Dr G Keith Douce,

Professor of Entomology College of Agricultural & Environmental Sciences The University of Georgia Bugwood Network

Cogongrass Distribution

The introduction of Cogongrass into the United States was initially accidental though use as

a packing material for shipment of orange plants form Japan to Grand Bay, AL in the winter

of 1912 Other early introductions were made in Mississippi and Florida in forage test trialsand for erosion control Since that time it has spread throughout the southeastern statesfrom Alabama west through Mississippi to Louisiana and east to South Carolina Currentlythere are over 1 million acres in Florida and several thousands of acres in Alabama andMississippi

Ornamental introductions continue to be made in the U.S with the numerous “red cultivars”offered by nurseries that are subject to much debate by invasive plant researchers andmanagers as to their “stated” lack of potential to revert to the “invasive” form In morenorthern latitudes cogongrass may not successfully overwinter but most of the Eastern U.S.and Pacific Northwest states may be at risk

County level infestations of cogongrass October 2007 EDDMaps – Bugwood Network

The Spread of cogongrass in Georgia The recent spread/detection in Georgia over the

past 10 years has accelerated to 25 new infestations per year

Number of infestations of cogongrass in Georgia tracked over the past 13 years.

Vectors of Cogongrass Spread

Cogongrass spreads by by both seed and rhizomes Windblown seed can move severalmiles in air currents and both seed and rhizomes move even farther when hitchiking on

equipment, mulch, and fill materials Vegetative spread in existing infestations was recentlyfound to exceed 200 sq ft per day in drought conditions in the Florida Panhandle (C.Ramsey, USDA APHIS-PPQ-CPHST, personal communication) Spread along highway right-of-ways through road construction and other maintance activities has resulted in widespreadmovement throughout Alabama, Mississippi and Florida Todate, most infestations inGeorgia and South Carolina have been introduced by contaminated equipment used for sitepreparation, tree planting, wildlife food plot preparation, powerline installation, as well asmovement of contaminated fill dirt and other direct movement by man

Elements of Prevention Programs

Creating awareness of the potential of spread and impacts on management is a critical

outreach programming component and the audience is vast The call for participation in thisconference shows the comprehensive need to inform and educate “ land owners andmanagers, contractors and consultants, State and federal agency management staff, policymakers, researchers, citizens, commodity group leaders, lawmakers, equipment andherbicide manufacturers, distributors, and retailers in Alabama, Arkansas, Florida, Georgia,Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, and Texas Participation isparticularly encouraged by State departments of agriculture, conservation, transportation,and forestry; State cooperative extension leadership, specialists and agents; State andCounty Highway and Roads Departments; Soil and Water Conservation Districts andResource Conservation and Development leadership and staff; USDA Natural ResourcesConservation Service, USDA Forest Service, USDI Park Service, and U.S Fish and WildlifeService leadership and staff “

Heightening awareness among land managers, loggers, highway, ROW, and utility contractors, hunters, farmers, nursery operators, and the general public will be necessary to reduce the potential movement of cogongrass that can be associated with their every day management activities In an effort to reduce the

introduction of new infestations, preventative measures, including equipment sanitation andoff-site material quarantines, should be highlighted through educational programs forforesters, natural resource managers, highway and ROW maintenance workers, farmers,landscapers and the general public

Encouraging proper equipment sanitation practices when operating on infested sites

and moving equipment to other locations to prevent spread include:

• Cleaning of radiators, screens, and equipment parts that collect seed or come into contact with the soil and rhizomes;

• Inspecting sources of off-site material including soil, gravel, and mulch for invasive species; and

• Establishing central staging areas on a property when equipment and material from off-site are stored or staged to allow easy inspection and monitoring for the introduction of invasives

Improved cogongrass identification, detection, and reporting State Department of

Agriculture nursery inspectors in Georgia and South Carolina have recently received training

in order detect cogongrass in routine nursery inspections In-service training sessions andfield tours on cogongrass identification and management are being conducted across theSouth by State, Federal and University personnel

Early Detection, Rapid Response

While cogongrass has been established in several of our southeastern states for more than

90 years, its continued spread throughout the southeast, with potential into the Atlantic,Midwestern and West Coast states, requires a need for concerted efforts in Early Detectionand Rapid Response (EDRR) Aggressive educational efforts to help reduce the vectors ofspread along with “eyes on the ground” to rapidly identify new infestations followed byeffective initial treatment, follow-up and rehabilitation/restoration can limit the expansion ofcogongrass

All of the southeastern states have implemented programs to control existing populations atvarious levels In Georgia and South Carolina, presently at the forefront of the advance,state-level EDRR programs have been implemented With support from USDA ForestService, USDA APHIS-PPQ, USGS, state agencies, state Exotic Pest Plant Councils, anduniversity cooperators, infestations are being mapped and treated

Through the Bugwood Networks Early Detection and Distribution Mapping System (EDDMapS) a database with all information on Georgia’s cogongrass infestations and

treatments is stored in a Microsoft SQL 2005 Server New infestations and treatment recordsare sent to Bugwood personnel for entry into the database All dates and types oftreatments are kept in a separate table and tied to each individual infestation to allow foreasy report generation and program evaluation With additional data provided by the othersoutheastern states, the database is used to dynamically create both the county-level andpoint distribution maps across the South

Cogongrass Information Resources

The University of Georgia’s Bugwood Network (www.bugwood.org) develops and provides

information and support for invasive species education, outreach, control and mappingacross the South, as well as programs nationally and internationally on all taxa of invasivespecies along with links to the Southeast Exotic Pest Plant Council (SE-EPPC), state EPPCs

and to EDDMapS through www.invasive.org

Of specific relevance to cogongrass efforts is www.cogongrass.org which provides

comprehensive information on cogongrass in Georgia along with links to other southeasternstate efforts on cogongrass To date, Alabama, Florida, Georgia, Louisiana, Mississippi, SouthCarolina and Texas have on-going research, education and/or control programs that aresupported by university, state and federal agency cooperators See

www.cogongrass.org/links.cfm for links to state programs and cooperators.

Selected References

Barron, M.C., G.E MacDonald, B.J., Brecke, and D.G Shilling 2003 Integrated approaches to

cogongrass [Imperata cylindrica (L.)Beauv.] management Proceedings of the Southern

Weed Science

Society 56:158

Bryson, C.T., and R Carter 1993 Cogongrass, Imperata cylindrica, in the United States

Weed

Technology 7:1005-1009

Dickens, R 1974 Cogongrass in Alabama after sixty years Weed Science 22:177-179

Dozier, H., J.E Gaffney, S.K McDonald, E.R.R.L Johnson, and D.G Shilling 1998 Cogongrass

Task Force Natural Areas Journal 27(3):226-231

Evans, C.W., D.J Moorhead, C.T Bargeron, and G.K Douce 2006 Field identification of

cogongrass with

comparisons to other commonly found grass species BW-2006-04 The University of Georgia

Bugwood

Network (online at http://www.cogongrass.org/cogongrassid.pdf)

Evans, C.W, DJ Moorhead, C.T Bargeron, and G.K Douce 2006 Invasive plant responses to

ANR-1321 (online at http://www.aces.edu/pubs/docs/A/ANR-1321/ANR-1321.pdf)

MacDonald, G.E 2004 Cogongrass (lmperata cylindrica) - biology, ecology, and

management Critical

Reviews in Plant Sciences 23:367-380

Tabor, P 1949 Cogongrass, Imperata cylindrica (L.) Beauv., in the southeastern United

A Summary of nearly 10 years of cogongrass

research

in MississippiJohn D Byrd, Jr., Extension/Research Professor of Weed Science

Mississippi State, MS 39762

Effective Herbicides for cogongrass control

Imazapyr (Arsenal, Chopper, and generics) and glyphosate (Roundup, Accord, and generics)have been found to be the most effective herbicides for cogongrass control Otherherbicides that we have tested that were determined not to be as effective as these twoactive ingredients are shown in Tables 1 and 2

In older studies and recommendations, two soil sterilants, Hyvar X (bromacil) at 18 or 24 lbai/acre (see 1972 Mississippi State University Cogongrass Control Guideline) and a high-ratemixture of Karmex (diuron) plus imazapyr at 10.3 plus 1.3 lb ai/acre controlled cogongrassbetter than glyphosate or imazapyr applied alone

Timing and sequence of glyphosate and imazapyr applications

Both glyphosate as a 2% mixture of Roundup Pro 4L and imazapyr at 24 fl oz/acre of Arsenal2L (0.375 lb ai/acre) consistently controlled cogongrass using:

• Fall applications (last week of September) and

• Spring applications followed by fall applications (last week of April or first week ofMay and last week of September)

Control levels of 80% or above have been achieved with these products applied in fall orspring followed by a fall treatment repeated over three growing seasons (Wright 2004-present)

Glyphosate applied in spring provides up to 90% control over summer months, but controltypically drops below 40% prior to the next spring application Cogongrass control withimazapyr applied only in spring requires a longer interval to reach an acceptable levelcompared to glyphosate applied at the same time However, when repeated, springapplications of imazapyr reach 80 to 90% control and it remains consistent until the nextspring

Frequency of herbicide applications

Reduced rates of imazapyr (0.0625 or 0.125 lb ai/acre or about 1%) and glyphosate (0.25 or0.5 lb ai/acre or about 1%) were evaluated as chemical mowing treatments for cogongrasswith the goal to maintain 50% growth suppression The first year of this study, cogongrassrequired only one application of the high rates of imazapyr per growing season, while allother treatments required two applications However, in the second year of the study, 2applications of all treatments were needed to maintain 50% control levels

Wiper mower and ropewick trials on cogongrass

Cogongrass control was evaluated with herbicides applied through conventional flat fannozzles at 20 gallons per acre (gpa) and the WetBlade mower at 1 gpa that wicks theherbicide on to the mown grass Treatments evaluated were imazapyr at 0.125 and 0.25 lbai/acre, clethodim at 0.125 lb ai/acre (Select), or glyphosate Roundup Pro and Touchdown

IQ formulations of glyphosate with surfactants were applied through nozzles at 4 lb ai/acre

or 2%, while the no-surfactant Accord was applied at the same rates through the WetBlade

A 33 or 50% solution of glyphosate or imazapyr was applied with a ropewick applicator tocogongrass in juvenile longleaf pines Cogongrass was wiped one or two directions to applysingle or double rates The concentration of glyphosate or imazapyr was not significant norwas the number of applications While the level of cogongrass control was not as high asnormally observed with imazapyr or glyphosate, this method did allow selective application

of both herbicides in longleaf pine which are susceptible to injury from either herbicide atnormally recommended application rates for cogongrass control

Surfactant additives to herbicide mixtures

The surfactant, Dyne A Pak, added at 1% of the spray volume, enhanced control ofcogongrass with imazapyr applied at rates of 0.125, 0.25, 0.375, 0.5, 0.625 lb ai/acrecompared to a nonionic surfactant As imazapyr rates increased, cogongrass controlincreased A significant increase in visual control was only observed at imazapyr rates of0.375 lb/acre or less after 1 year after treatment, while no significant differences weremeasured in rhizome biomass for any treatments (Chesser’s research 2005 to 2007)

Seedhead suppression with herbicides

Applications of glyphosate at 0.5 or 1.0 lb ai/acre, clethodim (Select) at 0.25 lb ai/acre,imazapic (Plateau) at 0.25 lb ai/acre, sulfometuron (Oust) at 0.09 lb ai/acre, or imazapyr at0.25 lb ai/acre to cogongrass in dormant or ‘boot head’ growth stage reduced the number ofviable cogongrass seed produced Trinexapac-ethyl at 0.08 lb ai/acre did not impact thenumber of seedheads or live seed

Herbicide and cropping systems for cogongrass suppression

Cogongrass was controlled 60% by no-till drill planted soybean Control improved to 95%with applications of either 1 lb ai glyphosate or 0.125 lb ai clethodim (Select or Intensityherbicides) However, soybean emergence has been successful at only one location eachyear (Ivy’s research 2004- present)

After two consecutive years of treatment, cogongrass control in a cropping system ofClearfield corn planted as no-till and treated with imazapyr at 0.38 lb ai/acre Arsenalpreemergence was statistically similar to cogongrass treated with 0.75 lb ai/acre Arsenalwithout the Clearfield corn Wildlife activity as observed by tracks, scat, feeding signs, such

as ears broken on stalk and fed upon, empty cobs on ground, etc and actual animalsdisturbed indicated wildlife activity (dove, turkey, squirrel, deer, raccoon, rabbit) was muchmore prevalent in the Clearfield corn than in cogongrass alone (Burns’ research 2004- 2005)

Mechanical, burning, and herbicide combinations

Cogongrass foliage removal by mowing or burning prior to application of glyphosate at 2.25

lb ai/acre or 0.63 lb ai/acre imazapyr improved visual control one year after treatment.Rhizome biomass was also reduced by all treatments except glyphosate applied after foliagewas burned (Myers’ research 2004-2006)

Mechanical control trials on cogongrass

Imazapyr at 0.63 lb ai/acre glyphosate at 2.25 lb ai/acre, or a mix of these two was applied

to cogongrass regrowth foliage after tillage with a rotary tiller, disk, or moldboard plow.Tillage prior to herbicide application improved cogongrass control 21 months after treatmentregardless of herbicide applied as evaluated by stem and rhizome weights Withoutherbicide application, the rotary tiller provided the best cogongrass control There was nosignificant difference among herbicides following a tillage treatment

and rhizome biomass 47 to 80% and the moldboard plow reduced these parameters 56 to80% and rhizome weights 47 to 85%

Cogongrass was mowed from March through October every other month, every month,every other week, or every week with a string trimmer After two years, cogongrass stemdensity was reduced 21, 27, 52, and 85%, respectively, at the end of the growing season,but stem density was not different than the unmowed plots at the start of the next season

At the start of the fourth year, cogongrass stem density failed to recover Plots were mowed

at the same frequency years four and five By the end of the fifth year, cogongrass stemdensity was reduced 22, 39, 66, and 86% in plots mowed bimonthly, monthly, biweekly, andweekly, respectively, compared to the untreated Rhizome biomass was reduced 17, 33, 60,and 70% in those respective plots Stem height and density in 2007 were still much lowerthan the unmowed cogongrass (Burnell’s research 2001 to 2004) Exceedingly frequentmowing over five years is impractical but has shown positive rhizome control

Ineffective herbicides tested

Flumioxazin (Valor or Broadstar) at 0.06, 0.125, or 0.25 lb ai/acre with 0.46 lb/acreammonium sulfate was mixed with 0.75 lb ai imazapyr or 1.5 lb ai/acre glyphosate andapplied to cogongrass No improvement in cogongrass control was observed with anytreatment compared to imazapyr or glyphosate applied without flumioxazin

Table 1 Herbicides evaluated in 1999 and 2000 that did not provide cogongrass control equal to glyphosate or imazapyr.

Herbicide(s)

Trade Name

Herbicide(s) Common Name

Finale, Ignite, Liberty, Rely glufosinate 0.34, 0.67

Trade Name

Herbicide(s) Common Name

Remote sensing of cogongrass with hyperspectral reflectance

Cogongrass can be differentiated from other warm season grasses with hyperspectralreflectance data Separation of cogongrass from other warm season grasses, such asbermudagrass, johnsongrass, centipedegrass, dallisgrass, and vaseygrass was moreaccurate when reflectance data were collected in summer compared to reflectance datataken of these species in winter (plants dormant), spring (cogongrass bloom), or fall (started

to senesce)

High resolution aerial images of Interstate 59 median and right of way and two-lane MShighway 528 right of way were used for broadscale cogongrass population detection Nearinfrared (NIR), red, green, and blue spectral reflectance values for each known class areawithin the images, along with spatial patterns and expert knowledge, were analyzed andused to train and recode the classified image Areas of the images suspected to becogongrass, other roadside vegetation, road/bare soil, forest, and shadow/water were used

to train the system for supervised classification and used to recode the unsupervisedclassification A database of GPS points of known locations for each class within each imagewere used to test the accuracy of each classification Overall accuracies for supervisedclassification of the images ranged from 85 to 95%, while unsupervised classification were

75 to 90% accurate Producers’ accuracies for the cogongrass class ranged from 54 to 71%with unsupervised techniques; however, supervised classification techniques resulted in 54-

Louisiana – A Historical Perspective

Dearl Sanders, Resident Coordinator and Edmiston Professor

LSU AgCenter Clinton, Louisiana

In Louisiana, congongrass in a pasture was first identified on a dairy farm in Angie in April of

1990 Prior to 1990 it had primarily been restricted to an urban area east of New Orleans

An initial survey of the immediate area and surrounding parishes (counties) indicatedinfestations on an additional eight farms Infestations varied in size from just a few feet indiameter up to approximately 10 acres

An attempt to determine the overall extent of the infestations was conducted by Dr BuddyDayton (area dairy specialist) and county agents from the area through a series of growermeetings, farm visits, mass media announcements and informational displays at parish fairs

A total of 12 different farms were found to have infestations, none exceeding 10 acres All ofthe infested fields were confined to Washington, St Tammany and Tangipahoa Parishes(parishes in extreme southeastern Louisiana adjacent to Mississippi)

In May of 1990 rhizomes from one infested field were collected and potted in a greenhouse

on campus in Baton Rouge A variety of post-emergent herbicides were screened on 6-8inch new-growth plants Herbicide screening was conducted by Dr Jim Griffin and included anumber of sugarcane herbicides, since Dr Griffin’s primary concern was the spread ofcogongrass into sugarcane Of the herbicides screened the most efficacious treatment was

a mixture of glyphosate at 2 lb.ai./acre plus sulfometuron (Oust) at 0.25 lb.ai./acre.Glyphosate and sulfometuron were obtained from their respective manufacturers’ insufficient amounts to treat the on-farm infestations Most of the farmers treated theinfestation sites, those that did not, chose to plow their sites Control ranged from good toexcellent, but had the negative impact of also killing desirable forages associated with theinfestation sites Summer plowing of the sites resulted in less control than the chemicaltreatments

In the spring of 1991 an infestation site was found associated with a sugarcane field nearDonaldsonville, LA After extensive additional survey work the infestation was found to beconfined to one edge of a field and had been there for 10 years (according to the farmmanager and verified by the owner) No additional plants could be found within the field.This field was monitored monthly throughout 1991 Herbicides used in the production of thissugarcane were screened in the greenhouse and were found to be ineffective againstcogongrass The infestation was limited to field margins that were not cultivated It washypothesized that the intense cultivation associated with sugarcane production severelylimited the spread of the pest

In the fall of 1991 and again in 1992 it was suggested that infested pastures be deep plowed(at least 6 inches deep) and planted to ryegrass This was not considered to be an unusual

consecutive years Results were outstanding, with infestations within the planted areasbeing reduced by greater than 95% Infestations remained in the pastures in areas thatcould not be plowed, ie: fences, shade trees, water troughs, etc Chemical treatments forthese areas were recommended and continue until today Fences and non-crop areasassociated with the pastures were treated with glyphosate or glyphosate plus sulfometuron

or imazapyr Areas not treated remain sources of re-infestation

Infestations of cogongrass have continued to increase along roadsides, transmission linesand in forest sites throughout the three parish region Attempts at chemical control havecontinued on these sites with varying degrees of success No additional pasture or forageinfestation sites have been reported to the author in the three parish region since 1995

In 2000, a pasture on the western side of state near Leesville, LA was found to be infestedand the same recommendations were made However the landowner refused to spray orplow and plant winter forage and the infestation has become a legal matter

Louisiana’s Current Recommendations for Cogongrass in Pastures Are:

• Prepare a complete fall seedbed, utilizing a finishing tool with sweeps if possible to deposit crowns and rhizomes at the soil’s surface.

• Plant ryegrass at a minimum of 30 lbs/acre alone or in combination with other winter forages.

• Do not overgraze the ryegrass in the infested areas.

• Allow the ryegrass in infested areas to naturally senesce, allowing full season competition before removal

• Spray all fencerows and noncrop areas with glyphosate alone or in combination with sulfometuron (Oust, etc.) or imazapyr (Arsenal, etc.) where allowed

• Practice good sanitation to prevent re-infestation

a challenge to prevent further spread

Wilson Faircloth, Research Agronomist, USDA Agricultural Research Service, Dawson, Georgia

1Highway and utility rights-of-way (ROW) connect even the most rural areas with major metropolitan areas in the United States Perhaps just as importantly, these

ROWs connect seaports, airports, and international borders with the remainder of thecountry This network of ROW has been shown to be pathways for the movement of invasiveplant species (Harper-Lore 2003) Rights-of-way, highways in particular, are conducive toinvasive grass infestation for several reasons Grasses are usually the desired species on

many ROWs Perennial species such as bahiagrass (Paspalum notatum Fluegge), common bermudagrass [Cynodon dactylon (L.) Pers.], and tall fescue (Lolium arundinaceum S J.

Darbyshire) are attractive, easy-to-maintain, provide erosion control, safe (low-growing forvisibility), and pose a minimal fire hazard Most of these grasses tolerate occasional mowing.Mechanical and herbicidal control of broadleaved plants is simple and cost-effective onROW; however, control of an invasive grass within a desirable grass is both challenging andoften costly to maintenance personnel

Movement of cogongrass along ROWs

Wilcut et al (1988a) first suggested movement of cogongrass along the Interstate 65 ROW

in Alabama via seed blown by the prevailing winds Willard et al (1990) also acknowledgedthe importance of ROW maintenance operations in cogongrass dispersal in Florida, however,his research indicated rhizome transport as the primary means of movement As indicated

by the previous researchers, cogongrass is an ideal invader of highway ROWs Not only mayseed move with prevailing winds, but vehicles offer the chance of long-distance dispersal Inaddition to providing access to un-infested areas, the presence of cogongrass on ROWs isaesthetically unpleasing and poses safety concerns due to its fire hazard Fire fueled bycogongrass is a liability concern for ROW managers, not only due to smoke managementand the safety of motorists, but also due to property loss from adjoining landowners

Control measures that could be utilized in ROW situations include both mechanical and herbicidal means Sajise (1972) first reported that mowing cogongrass

was only effective in removing aerial portions of plants Further research indicated thatmowing reduced above-ground foliage and total rhizome mass when repeated on a monthlyschedule, but the grass remained viable at the end the season (Willard and Shilling 1990).This research would indicate that occasional mowing has little effect on the regenerativecapacity of cogongrass Burnell et al (2003) demonstrated that weekly mowing ofcogongrass reduced the number of plants per unit area by 74%; however, much like Willardand Shilling (1990) cogongrass resprouted, even after two consecutive seasons oftreatment Shallow tillage (less than 3 in deep), such as discing, may be effective ifrepeated frequently (Johnson 1999) Repeated deep tillage (greater than 3 in deep) maycontrol cogongrass by inverting, burying, and exposing rhizomes but is not always possible

on a ROW (Chikoye et al 2000; Wilcut et al 1988)

Effective herbicidal control of cogongrass is currently limited primarily to two compounds: glyphosate (Roundup ® , etc…) and imazapyr (Arsenal ® , etc…).

Glyphosate has been reportedly used at rates up to 14 lb active ingredient (ai) per acre fornon-selective control in a variety of situations (Faircloth et al 2003; Miller 2000; Peyton et al

demonstrated that two mowings or discings in combination with a single glyphosateapplication at 3 lb ai/acre reduced rhizome biomass by at least 80% one year aftertreatment Re-treatment is necessary and should occur yearly until the rhizome system isdepleted (Bryson and Carter 1993; Jose et al 2002) Imazapyr offers limited selectivecontrol of cogongrass in unimproved bahiagrass and bermudagrass (Johnson et al.1999).Willard et al (1996, 1997) reported that imazapyr at 0.7 lb ai/acre controlled cogongrass up

to two years after treatment Imazapyr was significantly more effective at comparable ratesthan glyphosate in a study by Miller (2000) Johnson et al (1999) obtained 82% control ofcogongrass 18 months after treatment with sequential applications of imazapyr at 0.38 lbai/acre Mechanical treatments such as discing improved cogongrass control to 91% whenused in combination with the above treatments (Johnson et al 1999)

Given the extent to which cogongrass is found on public ROWs in Alabama (see figure below), it is necessary to develop integrated vegetation management plans

for cogongrass These plans must

include herbicides, mowing, andrevegetion with desirable andmanageable species

Experiments were begun in 2000 toaddress just such issues Manycombinations of glyphosate, imazapyr,mowing, and cover crops were tested onsevere cogongrass infestations on actualROWs The primary objective of thesestudies was to re-establish bahiagrass orbermudagrass into cogongrass infestedareas These intensive studies were alsorepeated so that we could makerecommendations on the number ofyears of consecutive treatment needed

to eradicate an infestation ofcogongrass

1Control of cogongrass was only achieved with three successive years of intense management A tank-mix

combination of glyphosate plusimazapyr applied in the fallincreased visual control anddecreased stand density, while notaffecting bahiagrass orbermudagrass conversion at onelocation Spring re-treatment withglyphosate increased visual control

favored Mowing was not an effective treatment alone; however, when performed monthlyand combined with herbicide, mowing showed some promise of reducing cogongrass up totwo years after treatment (YAT) (see fig at left)

Recommended Best Management Practices (BMPs) for cogongrass infestations on ROWs

As outlined previously, one of the objectives of this research was development of BMPs forcogongrass infestations on ROWs Recommendations are as follows:

• Care should be taken to prevent or exclude cogongrass infestations in unaffected areas; this includes but is not limited to, prudent selection of fill soil for earthwork operations and moratoria on the movement of soil from infested areas, or areas within close proximity to known infestations.

• The cleaning of earthwork and mowing machinery to remove propagules (seeds and rhizomes) when moving between infested and un-infested areas.

• Treatment of infestations with glyphosate (greater than or equal to 3 lb ai/acre) or glyphosate plus imazapyr (1.5 + 0.38 lb ai/acre) in the fall, followed by drill-seeding of a cover crop, followed by spring treatment of regrowth with glyphosate (≥3 lb ai/acre) and drill-seeding of a bermudagrass:bahiagrass seed mixture (2:1) at 30 lb/acre Herbicide application should be made in at least 15 gal/acre of solution to ensure adequate coverage This treatment program should be repeated yearly for three years

• Mowing of infestations as outlined in typical ROW protocols does not affect growth or survival and does not interfere with herbicide application Anecdotal evidence suggests mowing should not be conducted when seed heads are present to restrict seed movement on equipment Mowing will not affect the treatment regime outlined above