U.S. authorities are expanding the quarantine area for citrus black spot in Florida following new detections of the fungal disease.

The Animal and Plant Health Inspection Service (APHIS) is adding sections in four neighboring counties in the south of the state.

It is adding two sections in Charlotte County, 21 in Lee County, 26 in Hendry County, and four in Collier County.

"This action is in response to the confirmation of CBS during surveys conducted by APHIS and the Florida Department of Agriculture and Consumer Services, Division of Plant Industry (DPI)," APHIS said.

"The new sections are near areas that have previously been found positive for CBS."

APHIS said it is applying safeguarding measures and restrictions on the interstate movement or entry into foreign trade of regulated articles from the quarantine.

In 2010, CBS was first identified in the Collier and Hendry Counties of Florida.

Symptoms of CBS are most evident on mature fruit and typically remain latent on leaves with little to no symptom development until after the leaves die.

Fresh citrus fruit that is moved interstate from the CBS quarantine areas must be packed in commercial citrus packinghouses operating under a compliance agreement with APHIS and the fruit must be processed using APHIS-approved methods.

Citrus plant parts other than fresh fruit are prohibited from movement outside the quarantine area.

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