Sugar-cane disease new to La. found in two fields

BATON ROUGE — Orange rust, a fungus that can cut sugar production by as much as half, has been identified in two Louisiana sugar-cane fields, LSU AgCenter scientists say.

Average losses to the disease are considerably less than 50 percent, and Louisiana's cooler winters may help it avoid the damage that Florida has seen since the fungus was first identified there in 2007, AgCenter plant pathologist Jeff Hoy said Monday.

"I'm hoping the climate may not be favorable," he said.

Hoy said Florida has had to stop growing some varieties that were very susceptible to the fungus, which originated in Asia and is a problem in Australia. Until an epidemic in 2000 it was considered a minor disease in Australia, where it had been known since the 1890s, according to BSES Ltd, the Australian sugar industry's research and development arm.

"We were expecting it before now. We're hoping that's a sign that something's working in our favor," he said .

Another fungal disease, brown rust, hit Louisiana within a year after it was first identified in Florida, he said. Both fungi are spread by tiny wind-borne spores.

Consultants already are checking for an insect pest called stalk borers, he said, and have been asked to be on the lookout for orange rust as well. "They're in the cane all the time. If something's a problem, they would spot it pretty quickly."

AgCenter scientists are making their own surveys, as well, he said.

Both fungi damage sugar cane by reducing the leaf area available for photosynthesis.

Hoy said orange rust was found in two fields of a variety not yet commercially released. The variety, called "Ho 05-961," was being grown for later distribution and is a variety already known to be susceptible to the fungus. He said most of the varieties popular in Louisiana don't appear to be as vulnerable to orange rust.

The federal Environmental Protection Agency has approved emergency use of two fungicides against it if needed in Louisiana, Agriculture and Forestry Commissioner Mike Strain said.

source: houmatoday