Written by Franz Niederholzer, UC Farm Advisor, Colusa/Sutter/Yuba Counties and Joe Connell, UC Farm Advisor, Butte County In the last month, several PCAs and/or growers have reported trees in almond orchards in the south Sacramento Valley with symptoms similar to those of almond leaf scorch (ALS) — a disease caused by the bacterium Xylella fastidiosa. Five of the six fresh leaf samples subsequently submitted to a lab for ALS evaluation tested positive for Xylella fastidiosa. Varieties that appear more susceptible in the field include Peerless, Sonora, Winters, Livingston, and Wood Colony.