A new disease is showing up in olive trees. Cooperative Extension Orchard Systems Advisor Dani Lightle says the disease is so new there are still a lot of unknowns, including how far spread the disease is. “I don’t know that we know the extent of it,” Lightle says. “Up here in the Northern Sacramento Valley, right now we have not yet detected it on table olives although I do have some samples getting looked at. In the oil olives, the symptoms are very highly masked by olive knot. There is a good chance it is out there but growers have been looking at olive knot so much they don’t even see it. In the San Joaquin Valley, they have had some trees with very severe defoliation. There might be regional differences, there might be more than one species of pathogen and we just don’t know yet.”
The disease is so new there’s not even a name for it yet. Researchers have an idea of what’s causing the disease, but even that is not yet confirmed. “We don’t have confirmation that this is the pathogen that is causing the symptoms but the one we have isolated is related to a fungus that causes something called bullseye rot in apples and pears.”
We will continue following developments on this new olive crop problem and keep you updated.