Witchweed (Striga asiatica): an overview of management strategies in the USA

Abstract Witchweed, Striga asiatica (L.) O. Kuntz, was first found in the USA in 1956 in the states of North and South Carolina. It was recognized as, and declared by Federal and State Government Agencies, a threat to agriculture, particularly to corn ( Zea mays ), sorghum ( Sorghum bicolor ) and sugar-cane ( Saccharum officinarum ). The infested area was placed under both Federal and State quarantine to prevent its spread. Intensive surveys were conducted to identify the location and boundaries of each infested site. To date ∼ 175 000 hectares have been recorded as infested. In 1957, a USDA research facility was established at Whiteville, NC and in 1959 a research farm at Dillon, SC. Their original and exclusive purpose was to focus on research and development of eradication methods for this parasitic plant pest. Additional research has been conducted at NC State University and five other universities. From these facilities and resulting research has come knowledge of the biology, eradication methods and management procedures. A public awareness campaign has resulted in broadbased support for witchweed eradication. The operational activities are conducted by a staff of professional plant pest-control officers, technicians and control aids. The programme infrastructure ensures that a biologically sound programme of detection, regulatory and control activities are implemented on all infested sites. The programme consists of locating infestations, containment, public awareness, stopping witchweed reproduction and ridding the soil of witchweed seed. This programme has succeeded in eradicating witchweed from 145 000 ha ∼ 85% of the known infested area. It is anticipated that witchweed in the remaining 30 000 ha will be eradicated by the end of 1995, thus eliminating the threat of this devastating biological pollutant from the USA.