Giant Salvinia – An Invasive Alien Aquatic Plant in Thailand

Abstract

Giant salvinia (Salvinia molesta) is an introduced floating aquatic fern native to Brazil. It can reproduce vegetatively and under ideal growing conditions can double its biomass every 3-5 days. It can form mass on the water body, blocks out the sun’s rays from penetrating through, thereby inhibiting photosynthesis of submerged aquatic plants. Water quality is impaired under these masses, especially in areas with restricted water movement. Although the Act banning its introduction and cultivation has been promulgated since 1978, there is still a problem in controlling its distribution as well as in eradicating it. At present, however, only two areas, in which giant salvinia creates some problems, are in restricted areas in the Central and Southern parts of the Thailand. Luckily, the local administrative officers were effective in controlling its widespread distribution through people’s participation program in eradicating the giant salvinia. Chemical control is by the use of paraquat herbicide, but not officially recommended, except for use directly on the plant, or in turbid water. Although not at present troublesome for the waterways, awareness through surveillance should be done by notifying the public to be aware of its danger and not cultivating it