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Biology and Management of Cogongrass
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Permanent Link: http://ufdc.ufl.edu/IR00001834/00001
 Material Information
Title: Biology and Management of Cogongrass
Physical Description: Fact Sheet
Creator: Williams, Rick
Publisher: University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
Place of Publication: Gainesville, Fla.
Publication Date: 2008
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Acquisition: Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Melanie Mercer.
Publication Status: Published
General Note: "Original publication date May 2008."
General Note: "FOR191"
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Source Institution: University of Florida Institutional Repository
Holding Location: University of Florida
Rights Management: All rights reserved by the submitter.
System ID: IR00001834:00001

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FOR191 Biology and Management of Cogongrass1Rick Williams and Patrick J. Minogue2 1. This document is FOR191, one of a series of the School of Forest Resources and Conservation Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date May 2008. Visit the EDIS Web Site at http://edis.ifas.ufl.edu. 2. Rick Williams is an associate professor and extension forestry specialist in the School of Forest Resources and Conservation at the West Florida Research and Education Center, 5988 Hwy 90 Bld. 4900 Milton, FL 32583. Patrick Minogue is an assistant professor of silviculture in the School of Forest Resources and Conservation, North Florida Research and Education Center, 155 Research Road, Quincy, FL 32303. PLEASE READ AND FOLLOW ALL HERBICIDE LABEL DIRECTIONS:The use of trade names in this publication is solely for the purpose of providing information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication do not signify our approval to the exclusion of other suitable products. Treatment recommendations involve general herbicide prescriptions that have yielded acceptable levels of control in experimental trials. However, these recommendations are not guaranteed to work on every site. The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, DeanCogongrass is considered to be one of the 10 worst weeds in the world. It is native to warm regions of southeast Asia, but occurs in similar climates around the world. Cogongrass (Imperata cylindrica (L.) Beauv.) was accidentally introduced into Alabama in about 1911 as seed in packing materials from Japan (Dickens 1974). Purposeful introductions primarily for forage production soon followed in Alabama, Mississippi and Florida (Bryson and Carter 1993). Cogongrass was introduced into Florida in the 1930s and 1940s as potential forage and for soil stabilization purposes. However, people eventually realized that cogongrass was of little economic (forage) benefit and could become a serious pest. Consequently, it was placed on the noxious weed list, which prohibits new plantings (MacDonald et al. 2006).Figure 1. Cogongrass growing in a mature pine plantation. Note the lack of other vegetation in the cogongrass area. Credits: Rick Williams BiologyCogongrass is an aggressive, colony-forming perennial grass. Leaf blades are narrow, erect and often yellowish-green, with sharp-pointed tips and short fine hairs at the base; they are flat and smooth on the upper surface with a whitish mid-vein that is noticeably off-center, and the blade margins are finely toothed like a hack-saw blade. The flower stalks are cylindrical, white-silky and plume-like. Tiny flowers are paired on unequal stalks, and are surrounded by long white hairs. Cogongrass often attains a height of 3 to 5 feet late in a growing season (Miller 2003). Cogongrass spreads primarily from rhizomes, rhizome fragments, and windborne seeds.

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Biology and Management of Cogongrass 2Figure 2. Cogongrass in bloom. Credits: Rick Williams Even a small rhizome fragment can develop into a fully functional plant. Cogongrass is highly flammable when mature or dry and actually burns hotter than native grasses, but the roots and rhizomes are remarkably resistant to fire (Bryson and Carter 1993).Management StrategiesBiological Strategies Since cogongrass is out of its native range in the southeastern U.S., the normal biological control organisms are not present. Research in biological control methods is limited because we do not want to introduce another non-native pest to our environment. Fire Fire alone is not a good method for managing cogongrass. In fact, cogongrass thrives in a fire environment, burning at hotter temperatures than the native vegetation. The below-ground component of cogongrass is extensive and responds rapidly with new growth after a fire consumes the surface vegetation. Fire will only be beneficial if herbicides are used after the fire on the new growth. Machinery Cogongrass can be mowed, but mowing alone will not reduce cogongrass. Mowing is used primarily to remove the dense overstory vegetation before spraying new sprouts with a herbicide. Repeated disking has shown some promise of reducing cogongrass. The goal is to disk the cogongrass often enough to reduce the nutrient reserves stored in the roots and rhizomes. Disking followed by agricultural crops is being attempted in some places to eliminate or reduce infestations of cogongrass (personal communication with Mike Davidson Resource Management Services). Herbicides The most effective method of managing cogongrass is with herbicides. Two herbicides, glyphosate (RoundupPro, Razor Pro, or AccordXRT II) and imazapyr (Arsenal AC, Chopper Gen2, E-Pro 4, or Polaris AC) may be used alone or in combination to reduce cogongrass infestations (Miller 2003, Faircloth et al. 2005). Treat cogongrass in the fall while the leaves are still green. Thoroughly wet the leaves with glyphosate (2% solution, 8 oz. of product per 3 gallon mix) or imazapyr (1% solution, 4 oz. product per 3 gallon mix), or a combination of these herbicides. Always include a surfactant to improve herbicide absorption by the cogongrass foliage. When using imazapyr or imazapyr glyphosate combinations,, include 1 to 3 percent methylated seed oil (MSO) in your mixture. MSO improves herbicide uptake by plants, which is important in the management of difficult grasses such as cogongrass. Best results with standard glyphosate and imazapyr applications are obtained with herbicide treatment in September or October. Older infestations will be more difficult to manipulate due to dense leaf cover, and a second application may be necessary in April or May the following year before the plant produces flowers. New treatment trials at the University of Florida indicate that glyphosate herbicides at 1 lb. active ingredient per acre (1 quart of Roundup or equivalent per acre) mixed with one quart of Cogon-X per acre improves cogongrass eradication by 10% over glyphosate alone. Spring and summer treatments using glyphosate herbicide plus Cogon-X also proved to be effective as long as cogongrass was treated when it was green, growing and not stressed by lack of water.

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Biology and Management of Cogongrass 3In summary, imazapyr and glyphosate herbicides provide effective management strategies for manipulating cogongrass. Don't let this invasive plant go untreated and continue spreading on your property. Cogongrass infestations cause loss of productive forest areas, hinder forest activities and severely degrade wildlife habitat by replacing native plants. Important Considerations If you are spraying under pines glyphosate or imazapyr or a combination of these herbicides can be used. If you are spraying over the top of pine seedlings don't use glyphosate products, use Arsenal AC instead. If you are spraying around or under hardwood trees that you want to keep don't use imazapyr products like Arsenal AC or Chopper, use glyphosate products instead (don't spray hardwood foliage).Literature CitedBryson, 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(2):177-179. Faircloth, W. H., M. G. Patterson, J. H. Miller and D. H. Teem. 2005. Wanted dead not alive: Cogongrass. Alabama A&M and Auburn Universities, Alabama Cooperative Extension publication ANR-1241. 4 p. MacDonald, G. E., B. J. Brecke, J. F. Gaffney, K. A. Langeland, J. A. Ferrell and B. A. Sellers. 2006. Cogongrass (Imperata cylindrica (L.) Beauv.) biology, ecology and management in Florida. Univ. Florida, Cooperative Extension Service, SS-AGR-52. 3 p.http://edis.ifas.ufl.edu/WG202. Miller, J. H. 2003. Nonnative invasive plants of southern forests: A field guide for identification and control. USDA Forest Service Southern Research Station General Technical Report SRS-62. Asheville, NC. 93 p. Davidson, Mike, Resource Management Services, Cantonment, FL.Trade NamesAccord XRT is a registered trademark of Dow Agrosciences, LLC. Arsenal AC and Chopper Gen2 are registered trade marks of BASF. E-Pro 4 is a registered trade mark of Etigra Polaris SP is a registered trademark of Nufarm Turf and Speciality Razor Pro is a registered trade mark of Riverdale Roundup Pro is a registered trade mark of Monsanto. PLEASE READ AND FOLLOW ALL HERBICIDE LABEL DIRECTIONS:The use of trade names in this publication is solely for the purpose of providing information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication do not signify our approval to the exclusion of other suitable products. Treatment recommendations involve general herbicide prescriptions that have yielded acceptable levels of control in experimental trials. However, these recommendations are not guaranteed to work on every site.