Annals of Sri Lanka Department of Agriculture 2014. 16: 247-262 FALLOPIA CONVOLVULUS (L.) Á.LÖVE (POLYGONACEAE): PREDICTING POTENTIAL ENVIRONMENTAL AND ECONOMIC IMPACT TO SRI LANKA. W.J. NIMANTHIKA National Plant Quarantine Service, Canada Friendship Road, Katunayake, Sri Lanka ABSTRACT Fallopia convolvulus (L.) A. Love is a noxious weed having a cosmopolitan distribution. The species is not recorded in Sri Lankan flora although seeds of the species have been frequently detected in consignments of imported crop seeds. It was not yet recognized as a Regulated-weed to Sri Lanka due to deficiency in reliable information. Present study aimed to evaluate the potential impacts of this species. A Pest Risk Analysis was done. Growth performance was studied against Boerhavia diffusa, Aerva lanata, Dactyloctenium aegyptium, Cleome viscosa, Lantana camara and Ludwigia decurrens. Radical-emergence-time, seedling-emergence-time, height (1-week, 1-month), first-flower-bud- emergence-time, seed-number-per-plant, dry-weight, vertical/horizontal-root-spread, crown-cover and average-water-uptake-per-hour were used as growth parameters. Possible allelopathy effect of test species on the germination of reference species were studied using Raphanus sativus, Allium cepa and seeds from Strobilanthes viscosa, Clidemia hirta and Crotolaria retusa. Sandwich-method, agar-plate- well method and sand-tray method were used. The study revealed that F. convolvulus shows a similar or accelerated growth compared to the reference species. It was apparent that this species causes germination retardation in the study species. The overall outcome of this study emphasizes that the species is possibly a noxious weed in agricultural lands and if escapes, it has a potential to invade the natural plant communities. Therefore, the present study suggested that the importance of listing F. convolvulus as a quarantine weed to Sri Lanka. KEYWORDS: Allelopathy, Fallopia convolvulus, Pest Risk Analysis, Quarantine weed, Regulated weed. INTRODUCTION Fallopia convolvulus (L.) Á.Löve, commonly called as black bindweed, is a member of the family Polygonaceae. It is an annual climbing herb with a deep root system. The stem is slender and can reach up to 250 cm. Stem is freely branched from the base, trailing on the ground or twining around other plants. Leaves are alternately arranged and arrow head shaped. Flowers are small, inconspicuous, up to 5 mm in diameter, and in terminal racemes. Perianth is reddish green, white inside and along the margins. Fruit is a triangular achene, minutely pitted, and having a brownish black colour (Douglas et al., 1999; Holm et al., 1991). This cosmopolitan species (Franzini, 1982; Holm et al., 1991; Hume et al., 1983) is not yet recorded in Sri Lanka (Dassanayake and Claytaon, 1997), although seeds of this species are frequently detected at the weed science laboratory of National Plant Quarantine Service as a contaminant in the crop seed lots imported as planting material to the country.