Abstract
As to the growth characteristic of Senecio Madagascariensis (fireweed) it is spread to become a problem was clarified, and the dissemination of information about the problem was examined. Fireweed's germination ability does not decrease if the seed is saved for one year. In an experiment, fireweed was sown under pasture grasses that grow well on Awaji Island; the seed germinated but did not mature. The threshold of leaf length in grasses is more than 190.8mm in Lolium multiflorum and 295.4mm in Avena sativa. It is recognized that fireweed does not grow if it receives total integrated solar radiation of 8.5MJ/m2 and 7.6MJ/m2 or less. This indicates that the best method of pasture management to prevent fireweed invasion is covering the soil surface with grasses. Fireweed was designated a second groups level invasive species on 1 February 2006. Therefore it is need that the transmission of information and make up information collecting system.
