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Louisiana: February freeze killed lots of giant salvinia

March 27, 2021 GMT

BATON ROUGE, La. (AP) — The Louisiana Department of Wildlife and Fisheries says there’s a bit of good news from February’s big freeze -- it killed lake-choking invasive floating weeds.

The freeze didn’t eradicate giant salvinia or water hyacinth, but it did cut back giant salvina by about 95%, the department said in a news release.

The department says it’s harder to tell about water hyacinth, because their bulbs usually survive even if the plant looks dead.

The effects on giant salvinia varied around the state, department biologists said.

In north Louisiana, it doesn’t seem to be growing yet on waterbodies such as Turkey Creek Lake, Lake Darbonne and Caney Creek Reservoir. The department called that “a positive indicator that there has been an extensive kill of giant Salvinia.”

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It’s already showing signs of growing back in Caddo Lake, Lake Bistineau, Black Lake and Saline Lake, which had more extensive accumulations going into the winter. However, the department said much of that previous accumulation did die.

The department said minimal amounts have been seen in south Louisiana, but as temperatures rise it’s likely to grow back from hidden pockets around the marsh.

It said water hyacinth remains the worst aquatic weed in south Louisiana. “The winter storm in February burned the leaves off of most hyacinth plants, and it killed many; but the remainder have since leafed out and will likely grow substantially over the next two months,” it said.

LDWF biologists will keep checking lakes statewide, and herbicide crews will spray lakes with chronic giant salvinia problems. The department also uses other methods to control water weeds, including drawdowns, biological controls such as salvinia weevils, and private contractor spraying.