FACT SHEET

HOW YOU CAN HELP Itchgrass [ cochinchinensis (Lour.) W.D. Clayton] Currently, an effort is being made by Mississippi State University and the United States Geological Survey to determine Description, Distribution, and Management the distribution of Itchgrass in the Mid-South. This information, which is being maintained in an online database by Victor Maddox, Ph.D., Postdoctoral Associate, Mississippi State University Mississippi State University (www.gri.msstate.edu) is very important in tracking and monitoring movement and develop- Randy Westbrooks, Ph.D., Invasive Species Specialist, U.S. Geological Survey ing appropriate strategies for addressing the . Please send reports of suspected Itchgrass populations to: Victor John D. Byrd, Jr., Ph.D., Extension/Research Professor, Mississippi State University Maddox, GeoResources Institute, Box 9555, Mississippi State, MS 39762-9652, or submit information via the online GRI Publication #5017 form at www.gri.msstate.edu. Questions can be submitted at the online website or to Victor Maddox at 662-325-2313, E-mail: [email protected], or to John Madsen at Ph. 662-325-2428, E-mail: [email protected]. INTRODUCTION Itchgrass [Rottboellia chochinchinensis (Lour.) W.D. Clayton] is a non-native, annual grass that was Table 1. Chemical control tactics for itchgrass [Rottboellia chochinchinensis (Lour.) W.D. Clayton]. introduced at Miami, Florida in the 1920’s. It is a Method Herbicide Rate federal noxious weed, and is listed as a state Per acre or spot treatment noxious weed in twelve states including Alabama, Preemergence Arkansas, Louisiana, and Mississippi. It has been a serious weed in Louisiana for many years. clomazone Command 3ME 32 to 43 oz Itchgrass is a profusely tillering grass ( or pendimethalin Pendulum, 3.3EC, 19 to 58 oz Gramineae) that can be very competitive in row Prowl 3.3EC crops, pastures, and along roadsides (Figure 1). It Postemergence is spread primarily by seed and new populations asulam Asulox 128 oz continue to be found. Despite efforts to map and monitor its spread, the full extent of its invasion is glyphosate Several 32 oz of 3 lb ae per gallon formulation not clear. MSMA MSMA 32 oz nicosulfuron Accent 0.67 oz DESCRIPTION glufosinate Liberty 28 to 34 oz Fig. 1. Itchgrass [Rottboellia chochinchinensis (Lour.) W.D. Clayton] on a roadside Some texts indicate potentially four species of clethodim Select, 6 to 16 oz or 0.5% in Mississippi showing its ability to obstruct visibility. Photo by Gary Porter, MS Rottboellia L.f., but through recent taxonomic revi- Prism, 12 to 32 oz or 1% DOT. sion that number is probably closer to 2 or 3. Envoy Fluazifop Fusilade II 6 to 12 oz or 0.5% Itchgrass can reach 10 ft or more in height and tillers profusely (Figure 2). Itchgrass has short quizalofop Assure II 5 to 10 oz or 0.75% stiff hairs on the sheaths (Figure 3), especially sethoxydim Poast, 12 to 40 oz or 1% near the collar, which can puncture or irritate skin Poast Plus 24 to 36 oz or 1.5% when handled; hence the name ‘itchgrass’. Leaves are flat, around 1 inch wide tapering to a point, and have short hairs on the leaf surface (Figure 4). The is a raceme (Figure John D. Madsen, PhD 5) approximately 4 inches long with spikelets in MSU GeoResources Institute pairs and no awns. One of each spikelet pair is Box 9652 Mississippi State, MS 39762-9652 pedicellate (stalked) and sterile, the other is ses- 662-325-2428 or [email protected] sile and fertile. Each is attached to a thickened www.gri.msstate.edu rachis (Figure 6). The fertile, sessile spikelet is oblong and approximately ¼-inch in length. Published by the GeoResources Institute in cooperation with the United States Geological Survey (USGS). This info is to be published as part of the GeoResources Institute’s Invasive Species Spotlight program with the Extension Service at MSU. Itchgrass has been given various botanical names, including Aegilops exaltata L., Manisuris exaltata (L.) Kuntze, and Roettboellia exaltata (L.) L.f. Grasses in the genus Manisuris also occur in Fig. 2. Itchgrass with clumps of tillers. Photo by Gary Porter, MS DOT. the Mid-south region and may be confused with itchgrass. Unlike Manisuris, itchgrass is an an- nual and has prominent stiff hairs on the sheath. Hackelochloa granularis (L.) Kuntze is an annual with stiff sheath

Mississippi State University does not discriminate on the basis of race, color, religion, national origin, sex, sexual orientation or group affiliation, age, hairs, but unlike itchgrass the fertile spikelet is spherical and strongly pitted on the surface. handicap/disability, or veteran status. www.gri.msstate.edu February 2008 Itchgrass [Rottboellia cochinchinensis (Lour.) W.D. Clayton] Description, Distribution, and Management

DESCRIPTION, CONTINUED Plant growth is extremely rapid under optimum conditions with seed production initiated 6 to 7 weeds after emergence. Seed production continues throughout the growing season. Seed break off as they mature, but require a 5 to 6 month after- ripening period for germination to occur. Seed may retain viability in the soil for up to 4 years.

DISTRIBUTION AND HABITAT The genus Roettboellia is not native to the United States. Itch- grass is native to the Old World tropics, probably India. It is now widespread in the tropics and subtropics worldwide. It was ap- parently introduced into the United States for potential forage in the 1920s. Since that time, it had been reported in Alabama, Arkansas, Florida, Georgia, Indiana, Louisiana, Mississippi, North Carolina, and Texas (Figure 7). Field studies indicate that itch- grass may grow and produce seed as far north as Minnesota.

Itchgrass is a problem in row crops, especially grass crops, pastures and roadsides (Figure Fig. 7. Distribution of itchgrass [Rottboellia chochinchinensis (Lour.) W.D. Clayton] in the contiguous United States. 1). The spread of itchgrass Fig. 5. Itchgrass [Rottboellia chochinchinensis (Lour.) along roadsides indicates dis- W.D. Clayton] inflorescence. Photo by John Byrd. semination may be associated with highway right-of-way vege- tation management practices, CONTROL METHODS such as mowing. For itchgrass control, both pre-emergent and post-emergent chemical methods can be used (Table 1). Preemergent controls include clo- mazone and pendimethalin. Postemergent treatment options include broadcast applica- tions with asulam, glyphosate, MSMA, nicosul- furon, glufosinate, or clethodim for larger ar- eas. For small areas, spot treatment applica- tions with glyphosate, clethodim, fluazifop, quizalofop, or sethoxydim can be used. Cer- tain herbicides may be more effective while plants are young.

Currently, no widespread use of biological or cultural controls are utilized in the United States. Since itchgrass is an annual, timing of mowing may be important in control but more research is needed. Small patches of itch- Fig. 3. Itchgrass plants have stiff Fig. 4. The itchgrass leaf surface has short, soft Fig. 6. Mature spikelets from an itchgrass inflorescence presented as rachis grass may be manually removed, but precau- hairs. Photo by John Byrd. hairs along the sheath. Photo by segments, each with one fertile (left side of center segment) and one sterile tions should be taken to avoid the stiff hairs John Byrd. (right side of center segment), which is taller due to the pedicel. Photo by which may irritate the skin. Steve Hurst, USDA-NRCS PLANTS Database.