Despite efforts by agriculture authorities in Florida to eliminate canker in the south of the state, the disease has been found in the Indian River grapefruit-growing area.

According to US press reports, inspectors from federal plant health authorities have been searching private properties after markings caused by the canker were found last week on grapefruit trees on two private residential properties in Brevard county.

The discoveries are significant as they are the furthest north the disease has been discovered since it started to threaten citrus production in the south of the state in 2000. They are also the first in the hugely important Indian River grapefruit production area along the mid-Florida Atlantic coast.

The damaged trees were found three counties north of the previously northern-most discoveries, so far baffling inspectors.