Almond Band Canker Becoming a Big Problem

By Patrick Cavanaugh, Farm News Director

Brent Holtz is a UC cooperative extension Pomology Farm Advisor for San Joaquin County. He recently told California Ag Today about how the fungus band canker on almonds is becoming more prevalent in the San Joaquin Valley.

“I’ve seen a lot more band canker, which is caused by a pathogenic fungus, Botryosphaeria dothidea, and we’re seeing it on young orchards, especially in in San Joaquin county,” said Holtz.  “We’ve seen that a lot out in the delta and we’ve seen it in eastern San Joaquin county where the soils tend to be a little heavier, maybe old dairy ground and richer and we don’t really know why.”

“We’re seeing so much more, but it’s a fungus that infects usually the trunk or the main scaffolds, and we call it band canker because sap balls will come out at the site of the infection and create a band that circles around the trunk or the scaffold,” Holtz explained. “That’s why we call it band canker.”

It’s starting to show up in the orchards that have not been shaken yet, as a wound needs to happen before the infection sets in.

“We think it’s showing up in a lot of orchards before we start shaking the trees and usually in most cankers, we would have to have a wound that would have to happen first before the infection would take place either through a wound or a wound from shaking the tree,” Holtz said.

“Some of these orchards with symptoms tend to be trees that are growing very vigorously, and we suspect maybe that they’re growing so fast, growth cracks are created that the fungus may have got in and caused the infection.”

Trees with band canker on the trunk may not survive. And band cankered scaffolds have to be removed, which affects the tree’s architecture and will reduce yields.

There is evidence that micro sprinklers hitting the trunk could also increase the start of an infection.

“It seems to be showing up a little higher concentration where it was on a micro sprinkler irrigation system, where the sprinkler was actually hitting the trunk,” Holtz said. “We don’t seem to see it as much in orchards with a drip irrigation, so we are advising growers to consider drip or to put a splitter in their micro sprinklers so it can avoid wetting the trunk repeatedly with each irrigation.”