New cases of the destructive citrus canker disease have been found in Florida's DeSoto and Charlotte counties, and an expanded quarantine area is expected to be announced soon, according to newspaper reports.

Officials in St. Lucie and Indian River counties, on the state's eastern coast, are also trying to stop the spread of the highly contagious plant disease.

Workers from the Florida Department of Agriculture and Consumer Affairs were uprooting and burning orange trees in groves in DeSoto County, reported the local newspaper, the Sun-Herald,.

DeSoto, the fourth-largest orange-producing county in Florida, already had five areas under quarantine. The new outbreak will add 878 acres. And in Charlotte County, new state data shows that one in every 20 acres devoted to citrus production there has been devastated by canker.

Citrus canker, while not harmful to humans, causes bacterial infections that produce lesions on fruit and excessive fruit drop, which could devastate Florida's citrus industry.

Five separate outbreaks of citrus canker have been reported in Charlotte County. Last week, a massive canker outbreak was discovered in St. Lucie, the third-largest producer of oranges in Florida. State officials now need to investigate more than 8,500 properties there for the disease.

The spread of citrus canker was thought to have been caused by hurricane Charley as it passed over infected areas.

State law requires the removal of all trees within 1,900 feet of canker-infected trees.