86Ch<strong>in</strong>ese SilvergrassCh<strong>in</strong>ese silvergrass (Miscanthus s<strong>in</strong>ensis Andersson) is a tall, densely tufted, perennial grass, 5 to 10 feet (1.5 to 3 m)<strong>in</strong> height from a perennial root crown. It has long, slender, and upright-to-arch<strong>in</strong>g leaves with whitish upper midve<strong>in</strong>sand many loosely plumed panicles turn<strong>in</strong>g silvery to p<strong>in</strong>kish <strong>in</strong> fall. Dried grass rema<strong>in</strong>s stand<strong>in</strong>g with some seed headsdur<strong>in</strong>g w<strong>in</strong>ter, but seed viability is variable depend<strong>in</strong>g on cultivar and location. Spread<strong>in</strong>g <strong>in</strong>vasive cultivars have viableseeds. Species <strong>for</strong>ms extensive <strong>in</strong>festations by escap<strong>in</strong>g from older ornamental plant<strong>in</strong>gs to roadsides, <strong>for</strong>est marg<strong>in</strong>s,rights-of-way, and adjacent disturbed sites, especially after burn<strong>in</strong>g. Presently only an <strong>in</strong>vasive problem <strong>in</strong> the northerntier of States <strong>in</strong> the southern region, while projected widespread plant<strong>in</strong>gs <strong>for</strong> biomass and biofuels could result <strong>in</strong> aggravatedproblems.<strong>Management</strong> strategies:Do not plant. Remove prior plant<strong>in</strong>gs, and control sprouts and seedl<strong>in</strong>gs. Bag and dispose of plants and seed heads<strong>in</strong> a dumpster or burn.Treat when new plants are young to prevent seed <strong>for</strong>mation.M<strong>in</strong>imize disturbance with<strong>in</strong> miles of where fertile plants occur, and anticipate wider occupation if plants are presentor adjacent be<strong>for</strong>e disturbance.Do not mow when there are seed heads.Burn<strong>in</strong>g treatments are suspected of hav<strong>in</strong>g m<strong>in</strong>imal effect, and dormant stand<strong>in</strong>g <strong>in</strong>festations <strong>in</strong> w<strong>in</strong>ter are highlyflammable and pose a fire hazard.Recommended control procedures:Thoroughly wet all leaves with one of the follow<strong>in</strong>g herbicides <strong>in</strong> water with a surfactant (September or October withmultiple applications to regrowth): Arsenal AC * as a 1-percent solution (4 ounces per 3-gallon mix). When safety tosurround<strong>in</strong>g vegetation is desired, a glyphosate herbicide as a 4-percent solution (1 p<strong>in</strong>t per 3-gallon mix) only to thetarget plants; or a comb<strong>in</strong>ation of the two herbicides, Arsenal AC * as a 0.5-percent solution (2 ounces per 3-gallonmix) plus a glyphosate herbicide as a 4-percent solution (2 ounces plus 1 p<strong>in</strong>t per 3-gallon mix). Repeat applicationswhen new growth reaches 2 feet (60 cm) <strong>in</strong> height.* Nontarget plants may be killed or <strong>in</strong>jured by root uptake.
87CogongrassCharles BrysonCogongrass [Imperata cyl<strong>in</strong>drica (L.) P. Beauv.] and the closely related native, Brazilian sat<strong>in</strong>tail (I. brasiliensis Tr<strong>in</strong>.), are aggressive,colony-<strong>for</strong>m<strong>in</strong>g dense erect perennial grasses 1 to 6 feet (30 to 180 cm) <strong>in</strong> height. Hybridization is probable and makesdifferentiation difficult. Both have tufts of long leaves hid<strong>in</strong>g short stems, yellow-green blades (each with an offcenter midve<strong>in</strong>and f<strong>in</strong>ely saw-toothed marg<strong>in</strong>s), and silver-plumed flowers and seeds <strong>in</strong> spr<strong>in</strong>g (sporadically year-round). Seed are dispersedby w<strong>in</strong>d and on contam<strong>in</strong>ated cloth<strong>in</strong>g, equipment, and products like p<strong>in</strong>estraw mulch and fill materials. Seed viability appearsat this time to be significantly less <strong>in</strong> northern Florida and southern Georgia and higher <strong>in</strong> southern Alabama and Mississippi.Dense stands of dried plants rema<strong>in</strong> stand<strong>in</strong>g dur<strong>in</strong>g w<strong>in</strong>ter to present a severe fire hazard, while rema<strong>in</strong><strong>in</strong>g green year-round<strong>in</strong> central and southern Florida. These species burn hot even when green.Infestations <strong>for</strong>m dense rhizome mats mak<strong>in</strong>g eradication difficult, because abundant shoot and rhizome buds usually sproutafter treatment or lay dormant to sprout with<strong>in</strong> months. Rhizomes are sharp tipped and can pierce roots of other plants. Older<strong>in</strong>festations will be more difficult to control than new <strong>in</strong>vasions that occur as circular patches.Both species are Federal and State noxious weeds, while red-tipped cultivars are still sold and planted <strong>in</strong> many <strong>Southern</strong> States.These cultivars, bred <strong>for</strong> cold hard<strong>in</strong>ess, have viable pollen that might spread to the <strong>in</strong>vasive cogongrass plants. Red cultivarscan revert to the green aggressive type. Some <strong>Southern</strong> States prohibit the sale of the red cultivars. Visit www.cogongrass.organd other State cogongrass Web sites <strong>for</strong> more details. Resemble Johnsongrass [Sorghum halepense (L.) Pers.]; purpletop[Tridens flavus (L.) Hitchc.]; silver plumegrass [Saccharum alopecuroidum (L.) Nutt.]; and sugarcane plumegrass [S. giganteum(Walter) Pers.]—all hav<strong>in</strong>g a stem, do not produce fluffy seed heads, and no sharp-tipped rhizomes jutt<strong>in</strong>g up from the soilsurface. Also resemble longleaf woodoats [Chasmanthium sessiliflorum (Poir.) Yates] that occurs <strong>in</strong> shaded colonies <strong>in</strong> <strong>for</strong>estsbut lacks offcenter midve<strong>in</strong>s and silky flowers hav<strong>in</strong>g tufts of spiked flowers and seeds along a slender stalk.<strong>Management</strong> strategies:Do not plant the red-tipped cultivars (Japanese bloodgrass and Red Baron). Remove prior plant<strong>in</strong>gs, and control sproutsand seedl<strong>in</strong>gs.Treat when new plants are young and located through frequent surveillance of lands <strong>in</strong> <strong>in</strong>fested zones.M<strong>in</strong>imize disturbance with<strong>in</strong> miles of where this plant occurs, and anticipate wider occupation when plants are present oradjacent be<strong>for</strong>e disturbance.Repeated cultivation and plant<strong>in</strong>g of aggressive grasses or herbicide resistant crops can restore pastures and croplands.Burn<strong>in</strong>g and bush-mow<strong>in</strong>g treatments can remove stand<strong>in</strong>g plants <strong>for</strong> more efficient herbicide treatments. However, burn<strong>in</strong>gusually causes rapid <strong>in</strong>festation expansion and can kill native shrubs and trees that constra<strong>in</strong> spread.Do not use or transport fill dirt, rock, hay, or p<strong>in</strong>estraw from <strong>in</strong>fested lands.Seed production can be stopped by mow<strong>in</strong>g, burn<strong>in</strong>g, or herbicide treatments <strong>in</strong> early stages of flower<strong>in</strong>g or even shortlybe<strong>for</strong>e flower<strong>in</strong>g. However, these treatments can prompt later flower<strong>in</strong>g/seed<strong>in</strong>g as well.Clean seed and rhizomes from equipment and personnel work<strong>in</strong>g <strong>in</strong> <strong>in</strong>festations be<strong>for</strong>e leav<strong>in</strong>g the <strong>in</strong>fested site.Forage quality is low, eaten only when shoots are young and tender by horses, goats, sheep, mules, and some cattle.Recommended control procedures:Thoroughly wet all leaves with one of the follow<strong>in</strong>g herbicides <strong>in</strong> water with a surfactant when grass is actively grow<strong>in</strong>g and atleast 1to 2 feet high or older growth from June to September: Chopper Gen2 * as a 2-percent solution (8 ounces per 3-gallonmix) or Arsenal AC * as a 1-percent solution (4 ounces per 3-gallon mix). Repeat applications <strong>in</strong> subsequent years may berequired <strong>for</strong> eradication. A glyphosate herbicide may be tank mixed as a 2- to 5-percent solution with Chopper Gen2 * at2 percent (8 ounces per 3-gallon mix) or Arsenal AC * at 1 percent (4 ounces per 3-gallon mix). This treatment will accelerateburndown of actively grow<strong>in</strong>g shoots but may not improve rhizome kill.When safety to surround<strong>in</strong>g vegetation is desired (especially hardwoods, shrubs, and p<strong>in</strong>es), apply a glyphosate herbicideas a 2- to 5-percent solution (8 to 20 ounces per 3-gallon mix). Two applications per grow<strong>in</strong>g season (just be<strong>for</strong>e flower<strong>in</strong>g<strong>in</strong> spr<strong>in</strong>g and aga<strong>in</strong> <strong>in</strong> late summer to regrowth) are typically necessary. Apply <strong>in</strong> successive years when regrowth is presentuntil no live rhizomes are observed <strong>for</strong> eradication; at the same time promote or establish desirable plants.* Nontarget plants may be killed or <strong>in</strong>jured by root uptake.
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