Water extracts of cogongrass foliage and
roots inhibited germination and seedling growth of bermudagrass
[Cynodon dactylon (L.) Pers.] and Italian ryegrass [Lolium
perenne L. ssp. multiflorum (Lam.) Husnot] at concentrations
as low as 0.5% (wt/vol). Furthermore, incorporation of foliage
and rhizome plus root residues in soil at concentrations as low
as 0.25% (wt/wt) inhibited seed germination and shoot and
root growth, indicating that cogongrass tissue and extracts
may contain allelochemicals that contribute to its invasiveness
and extreme competitiveness. Additional studies showed that
rhizome and root exudates of cogongrass contain numerous
plant growth inhibitors with selective effects against tested
invasive species at the level of 0.1 mg ml21 (Xuan et al. 2009).
The most potent component identified was 2,4-di-tertbutylphenol,
followed by iso-eugenol and 4-acetyl-2-methoxyphenol.