Cookies on Invasive Species Compendium

Like most websites we use cookies. This is to ensure that we give you the best experience possible.


Continuing to use  means you agree to our use of cookies. If you would like to, you can learn more about the cookies we use.

Have you tried our Horizon Scanning Tool (beta) for prioritizing invasive species threats?

We’d value your feedback on the tool. Our survey takes only five minutes to complete.


Use of azolla to suppress weeds in transplanted rice.


In trials in 3 fields of transplanted irrigated rice cv. IR50 each with a different weed flora, N at 0 or 100 kg/ha was applied and plots either weeded once 21 days after transplanting (d.a.t.), twice at 15 and 30 d.a.t., or not weeded, with or without inoculation with azolla (Azolla pinnata). At rice harvest, azolla gave up to 95.3% reduction in dry wt. of Monocharia vaginalis, 93.9% of Cyperus difformis and 86.7% of Echinochloa glabrescens, with similar control of other spp., including Paspalum sp. However, azolla failed to suppress Scirpus maritimus and Echinochloa crus-galli ssp. hispidula, which increased by 0.4 and 226.4%, resp. Where weeds were suppressed, rice yields from azolla-treated plots (up to 4.6 t/ha) were comparable with those from hand-weeded plots (up to 4.5 t/ha); yields from non-weeded controls were up to 3.4 t/ha. Where weed control failed, azolla-treated plots gave similar yields to non-weeded control plots.