The devastating citrus greening disease has been identified on the same property in California's Riverside County where it was previously found, marking the first time it has been found in the area since 2017.

Researchers have confirmed the presence of the disease, also known as HLB, on a kumquat tree the yard of a Riverside house, according to Tracy Moehnke, a spokeswoman for the Citrus Pest & Disease Prevention Program. 

“It can stay basically hidden in the tree and not express itself for years,” Riverside County Agricultural Commissioner Ruben Arroyo said.

Four properties in Riverside County have tested positive for HLB, all in the same area of the city of Riverside. San Bernardino County had one positive tes.

Meanwhile, 291 infected properties have been found in Los Angeles County, and 689 properties in Orange County, according to Moehnke.

The disease is transmitted tree-to-tree by the Asian citrus psyllid. The insect does not always carry the disease, but it is the only known vector. The psyllid was first detected in Southern California in 2008, and HLB was found in 2012 in Hacienda Heights.

Since then, Riverside officials say they’ve worked hard to stop the spread of the disease, which leaves citrus trees with mottled leaves and fruit that is misshapen and fails to ripen, remaining green. The fruit also tastes bitter. There is no known treatment for the disease and trees usually die within three to five years.