Sweet orange scab spreads to LA and Ventura counties, triggering quarantine

Topline:

Symptoms: Indicators of sweet orange scab include pustules on leaves that initially look like water spots and scabs on young fruit that can spread and eventually crack. While the inside of the fruit might be OK, the pathogen can lead to premature fruit drop and limit the growth of young trees. Tangerines and sweet oranges are particularly vulnerable. If you need help identifying the fungus, the USDA has a handy visual guide.

How does it spread? Via spores from the fungus Elsinöe australis, which can be transferred between trees by green waste, plant boxes and pruning equipment.

If you have it: Although there's currently no treatment available, according to the USDA, unlike with citrus greening disease, you do not have to remove trees on your property if they're infected. Remove and dispose of the fruit, and thoroughly sanitize any equipment that comes in contact with the infected plant matter.

Why it matters: The quarantine means that fruit and trees from the affected areas face restrictions on their movement. That's because the fungus is a threat to both residential and commercial citrus industries. It was long thought that sweet orange scab primarily affected trees in more humid environments such as Florida. But it has infected trees in the desert, raising concern that it could spread throughout California's citrus hub, the Central Valley.