Agriculture inspectors in Texas have detected the plant disease citrus greening in an orange tree, bringing to five the number of states where the tree-damaging disease has been confirmed, state and federal officials said on Wednesday.

The disease leaves the fruit safe to eat and poses no threat to human health but attacks a tree's vascular system, reducing fruit size and affecting color, sometimes causing fruit to drop before ripening, according to the Texas Department of Agriculture.

The disease has also been detected in Florida, Georgia, Louisiana and South Carolina and has damaged citrus industries in Florida, Africa, Asia and South America, the department said.

Texas ranks second among the states -- behind Florida -- in grapefruit production and third in orange production -- behind Florida and California.

Texas agriculture authorities imposed a five-mile quarantine around one affected tree discovered in an orange grove in San Juan in South Texas, the primary citrus-producing region in Texas' $140 million industry.

Citrus greening is caused by a bacterium typically transmitted by an insect called the citrus psyllid. There is no cure for infected trees.