Brown Flatsedge ( fuscus) A Potential Rice Weed Charles T. Bryson1 and Richard Carter2 1USDA-ARS, Southern Weed Science Research Unit, Stoneville, MS 38776 2Department of Biology, Valdosta State University, Valdosta, GA 31698

Introduction Results

Brown flatsedge (Cyperus fuscus L.) is a native to , Field observations at the three sites in Arkansas and Mississippi, , Indian subcontinent, and the Mediterranean Region of determined that brown flatsedge was highly dependent on persistent Northern Africa. It was first discovered in in moist soils or shallow standing water for establishment, growth, and 1877 and apparently was introduced around wharfs from seed production. Over a five-year period and under natural field contaminated ballast. Since that time, brown flatsedge has conditions, brown flatsedge germinated from late March and been discovered in Canada and U.S.A. In the U.S.A., it is early April until frost. were observed as early as found in Arkansas, California, Connecticut, Kansas, Maryland, May, and seed production continued until frost. Brown flatsedge Mississippi, Missouri, Nebraska, Nevada, New Jersey, scales were predominately green with a trace of reddish-brown or

Pennsylvania, South Dakota, and Virginia (McKenzie et al. 35 70 purple in the spring and summer months to predominately reddish- Cyperus fuscus Height Cyperus fuscus Plant Diameter 2 y= 84.0375/(1+exp(-(x-7.8704)/1.7873)) 1998; Bryson and Carter 2008). Dispersal of brown flatsedge 30 y=0.1794+1.3579x+0.1887x 60 2 brown to dark purple in the fall as day lengths become shorter and r2=0.9720 r =0.9945 has been attributed to waterfowl and human activities, 25 50 air temperatures become cooler than in the summer months. including use of construction equipment. Brown flatsedge was 20 40 In greenhouse experiments, ten-week old brown flatsedge plants

15 30

Height (cm) were 30.2 cm tall and 63.9 cm in diameter with dry weights of 1.4, reported as a weed in semitropical areas of the old world (cm) Diameter (Holm et al. 1979, Kukkonen 2001; Simpson and Inglis 2001; 10 20 2.0, 1.0, 0.5, 1.9 and 6.8 g for roots, leaves, culms, , Bryson and Carter 2008), where it is a significant weed in rice 5 10 inflorescences and whole plant, respectively. The first brown 0 0 (Weedon and Stephens 1969; Mingyuan and Dehu 1970; Holm 012345678910 012345678910 flatsedge culm appeared five weeks after emergence (WAE) and all et al. 1979). Because brown flatsedge was reported as a weed Time after emergence (weeks) Time after emergence (weeks) plants produced seed by nine WAE. Although brown flatsedge in semitropical areas of the Old World where it is a significant 1.6 2.5 seems to be in the lag phase, it could pose a threat to rice production Cyperus fuscus leaf dry weight Cyperus fuscus Root Dry Weight y= 1.9351/(1+exp(-(x-6.8233)/0.5560)) 1.4 y= 2.0539/(1+exp(-(x-9.0863)/1.2774)) weed in rice and it was recently detected in the rice production r2=0.9980 in Arkansas, California, Louisiana, Mississippi, Missouri, r2=0.9966 2.0 areas of the Delta Region, research was initiated at Stoneville, 1.2 Tennessee, and Texas. Additional research is needed to determine Mississippi, to study the basic biology and ecology of brown 1.0 1.5 the ecological range potential and to develop control methods for 0.8

1.0 flatsedge. 0.6 brown flatsedge. Root weight (g) weight Root Leaf dry weight (g) dry weight Leaf

0.4 0.5

Material and Methods 0.2

0.0 0.0 012345678910 012345678910 Field observations were made at three sites, Chicot County, Time after emergence (weeks) Time after emergence (weeks) Arkansas, and Pearl River and Washington counties, Mississippi, 1.4 0.6 from early spring until frost during 2003 to 2007. Data on dates Cyperus fuscus culm dry weight Cyperus fuscus dry weight 2 1.2 y=1.1636exp(-.5((x-9.4980)/0.9012) ) y=0.5408exp(-.5((x-9.4233)/1.3835)2) 2 0.5 germination, first culm and , and seed production were r =0.9970 r2=0.9950 1.0 recorded. Greenhouse studies were conducted in 2007 and 2008 at 0.4 0.8 Stoneville, Mississippi, to determine growth parameters and 0.3 0.6

0.2 Culm dry weight (g) weight dry Culm reproductive potential of brown flatsedge. Brown flatsedge seed 0.4 (g) weight dry Bract

0.1 were collected form Washington County, Mississippi, during the fall 0.2 of 2006 and planted during the summer of 2007. Seeds were planted 0.0 0.0 012345678910 012345678910 in 15-cm diam. plastic pots filled with a 1:1 mixture of potting Time after emergence (weeks) Time after emergence (weeks) media and soil (Bosket sandy loam, fine-loamy, mixed thermic Molic Hapludalfs). Upon emergence, seedlings were thinned to one 2.0 8 Cyperus fuscus seed head dry weight Cyperus fuscus whole plant weight y= 7.7235/(1+exp(-(x-8.2627)/0.8533)) y= 1.9619/(1+exp(-(x-8.8132)/0.3459)) 2 plant per pot and grown in a greenhouse set to 30/22 C (± 3 C) r2 =0.9999 r =0.9982 6 day/night temperature. Natural light was supplemented with light 1.5 Acknowledgments from sodium vapor lamps to provide at least 14-h of light each day. 1.0 4 Plants were watered from below and were grown in greenhouse for 0.5 2 Wholeplant dry weight(g) 10 weeks. Brown flatsedge plant height, diameter, and number of dry weight Inflorescence (g) We thank Paige Goodlett for technical assistance in the greenhouse leaves per plant, and days to first flower were recorded. All plants 0.0 0 studies. 012345678910 012345678910 were harvested and dry weights were recorded for roots, leaves, Time after emergence (weeks) Time after emergence (weeks) culms, bracts, and inflorescences. Literature Cited

Bryson, C. T. and R. Carter. 2008. The Significance of as Weeds. Pp. 15-102 in R. F. C. Naczi & B. A. Ford (editors), Sedges: Uses, Diversity, and Systematics of the Cyperaceae. Monogr. Syst. Bot. Missouri Bot. Gard. 108. Holm, L., J. V. Pancho, J. P. Herberger, and D. L. Plucknett. 1979. A geographical atlas of world weeds. John Wiley and Sons, New York. Kukkonen, I. 2001. Cyperaceae, No. 206. Pages 1-277, in S. I. Ali and M. Qaiser, Flora of Pakistan. University of Karachi and Missouri Botancal Garden, Karachi and St. Louis. McKenzie, P. M., B. Jacobs, C. T. Bryson, G. C. Tucker, and R. Carter. 1998. Cyperus fuscus (Cyperaceae), new to Missouri and Nevada, with comments on its occurrence in North America. Sida 18:325-333. Miongyuan, X. and M. Dehu. 1970. Farmland weeds of China: a collection of coloured illustrated plates. Agricultural Publishing House, Beijing, China. Simpson, D. A. and C. A. Inglis. 2001. Cyperaceae of economic, ethnobotanical, and horticultural importance: a checklist. Kew Bulletin 56:257-360. Weedon, R. R. and H. A. Stephens. 1969. Cyperus fuscus in Nebraska and South Dakota. Rhodora 71:433.