HOUSTON (AP) - Some Central Texas pecan farmers who believe sulfur dioxide emissions from a coal-fired power plant slowly killed their orchards want compensation from the operator and the city of Austin.

The demand was made Monday at a news conference.

The Texas Pecan Alliance and scientists with Sierra Club say research shows sulfur dioxide kills vegetation, and is especially harmful to pecan trees. They say production started decreasing in 1980, a year after the Fayette County plant began operating.

Since then, pecan grower Harvey Hayek says thousands of trees along some 100 miles of the Colorado River have died, including two-thirds of the trees on his family's 250-acre ranch.

The Lower Colorado River Authority says it is installing equipment that will remove more than 90 percent of the harmful emissions.