Something is killing a plant vital to holding together the river delta in Southeast Louisiana

(WVUE) - Earl Armstrong rummages through a stand of roseau cane near the mouth of the Mississippi River in search of a small alien that seems to be causing a world of trouble.

"As many as you want to pick, there will be seven or eight out of 10 that's got scale on it," Armstrong said of the roseau plants.

An insect scale native to Asia and smaller than a fingernail attaches itself to the roseau, a large reed that is common in the river delta. For months now, Armstrong has been watching the roseau die at an alarming rate and the land it clings to disappear.

"In places, it's two or three times as bad," Armstrong said.

The Mississippi River delta is home to world's largest contiguous stand of roseau. The Louisiana Department of Wildlife and Fisheries estimates the scale has damaged more than 100,000 acres of marsh.

"I'm calling this ecological meltdown," said Linda Hooper-Bui, an LSU researcher specializing in the study of insects.  "It is catastrophic. They have mouth parts that insert into the plant and they suck the juices out of the plant."

Roseau, part of the backbone of the delta, is highly tolerant of both salinity and fresh water, and of the wind-driven waves that cause erosion.

"If we lose it, then we're going to lose a lot of our ability to fight erosion on the lower Mississippi River, the Bird's Foot Delta," said Todd Baker, Biologist Director of Wildlife and Fisheries Coastal and Non-game Resources Division.

"In certain places, there's no plant that's going to replace the roseau, and we're going to end up having more open water," said Windell Curole, General Manager of the South Lafourche Levee District.

Earl Armstrong finds one example of the problem in West Bay south of Venice, where a cut in the river has dumped sediment and built land. Over time, it formed sandbars, then small islands now covered in vegetation. Here, two invasive species seem to team up to attack the delta. As the roseau grows weaker, water hyacinth move in to replace the cane.

"The island is just getting weaker and weaker," Armstrong said.

Two-thirds of the island has been replaced by hyacinth and open water.

"These islands would never do this if we didn't have this scale problem."

The outbreak was first noticed about a year ago near the mouth of the river, but it has since spread to 11 other parishes, according to a state survey earlier this month. However, biologists say the outbreak may actually have started much earlier and only drew attention when the roseau started dying.

Large swaths of the delta turned brown when they should have radiated green this spring and summer. Insect experts say the scale could be hitching a ride on boats, but more likely, tides and wind-driven waves spread them.

"Whatever way the wind is going, small insects can be dispersed through wind," Hooper-Bui said.

The adult females do not move, but their tiny offspring - roughly the size of a pin head - are mobile.

"I am not going to immediately ascribe the problem to the insects," said Hooper-Bui, who cautions against a rush to judgment.

She believes the insects may merely be a symptom of some other problem.

"Stressed plants give out signals, and they get attacked," Hooper-Bui said.

She says the problem could be the result of anything from insects carrying a disease to changes in salinity or chemicals in soils. Or, she speculates, it could be something as simple as unusually high water over a period of time along the coast.

Hooper-Bui points out plants in your backyard frequently attract scales, but do not die from them. If enough land disappears, some navigation interests have suggested it could compromise the shipping channels near the mouth of the Mississippi.

"I will tell you there is a lot of pressure for an instant solution, and science is really not a great way to get that," Hooper-Bui said.

Biologists fear the possible cures would be as bad as the disease. Insecticide, for example, could affect shrimp, crabs or other critters that wear their bones on the outside of their bodies.

Burning the cane has also been discussed, but Hooper-Bui points out that since roseau does not burn easily, that would require an accelerant of some sort, which is a violation of the Clean Water Act.

"By the end of next year or maybe the year after, there won't even be an island here," Armstrong said.

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