California Department of Food and Agriculture surveyors have detected citrus scab in two additional locations since the initial find in Imperial County in October.
The new finds were on grapefruit collected in a residential area of Los Angeles County and from a commercial grapefruit grove in Riverside County on Nov. 1, according to a National Plant Protection organizations pest alert.
The first find in Imperial County involved lemon fruit samples collected from two separate commercial groves on Oct. 11.
The new finds are the result of intensive surveys by CDFA as part of the cooperative Citrus Health Response Program.
The delimiting surveys in the state's citrus-producing regions will continue.
Sweet orange scab was first found in Texas in 2010 and has since been detected in Florida, Louisiana, Mississippi and Arizona.
The fungal disease creates blemishes on the fruit peel and at times on leaves and twigs. Although the lesions don't affect internal fruit quality, they may affect fruit marketability.
The disease also can raise quarantine red flags among some trading partners.
Sweet orange scab also has been found in South America and Oceania, which includes the Cook Islands Fiji and Samoa.