The Citrus Pest & Disease Prevention Program in California recently detected sweet orange scab (SOS) in new areas of the state. Additionally, an unofficial lime swallowtail butterfly (LSB) sample was identified from Los Angeles County, and several LSB sightings have been reported in Los Angeles and San Luis Obispo counties.
SWEET ORANGE SCAB
SOS is a cosmetic fungal disease that impacts the marketability of the fruit and affects all citrus. SOS is caused by the fungus Elsinöe australis, which is dispersed by water. The disease is recognizable by the scab-like lesions on fruit, and less frequently on leaves and twigs. SOS can cause premature fruit drop and stunt young nursery trees and new field plantings but has little impact on fruit quality.
A positive detection of SOS was found during a commodity survey on the west side of Riverside County, the fourth detection in California within the last year and a half. To help protect citrus from SOS, growers and packinghouses within five miles from an SOS detection, and packinghouses throughout the state receiving fruit from groves within 5 miles from an SOS detection, are currently required to follow these measures:
- Sign an SOS compliance agreement with the California Department of Food and Agriculture (CDFA).
- Disinfect all fruit and field bins.
- Collect and appropriately dispose of green waste.
Per the Citrus Pest & Disease Prevention Committee’s direction, CDFA is also reviewing SOS impacts and analyzing the need to establish SOS interior quarantine regulations. Currently the program regulates areas within a 5-mile radius from each SOS detection, following the U.S. Department of Agriculture’s quarantine protocols.
Working with growers, CDFA is exploring the rule-making process to create state interior quarantines, which will avoid a broader statewide quarantine that would be more burdensome to the industry.
LIME SWALLOWTAIL BUTTERFLY
LSB in the larval stage eats citrus leaves and has been very damaging to nursery stock in other parts of the world. The larva looks similar to bird guano before maturing into green caterpillars. As butterflies, they are largely black with irregular yellow spots on the outer wings.
Source: Citrus Pest & Disease Prevention Program
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