|Pennisetum clandestinum Chiov.|
This rapidly growing, partially scrambling, rhizomatous plant is a favored, but overrated, rangeland grass. It is a serious pest in forests because, apart from shading out shrubs and herbs, it releases allelopathic substances which kill almost all other species in the vicinity (Sanchez and Davis 1969). It burns very slowly and generally retards fire. It has been evaluated for biological control but no action will be taken because of its agricultural importance (Gardner and Davis 1982). A rust (Phakospora aroda (Har. and Pat.) Mains) has recently become established on all islands but its impact is not yet known (Gardner 1984). The grass can be eradicated by spraying with 0.5% glyphosate (Gardner and Kageler 1983) or Dalapon (Hosaka 1958).
It is found on all major islands from 500-2,000 m in dry and mesic habitats. It will also invade wet environments when the forest is disturbed. It has been classified as a noxious weed by the U.S. Department of Agriculture in all states except Hawai'i.