P-659 - Implementing area-wide aflatoxin management programs using atoxigenic strain biocontrol technology to lower aflatoxin risks in tree nuts in California

Monday, August 4, 2025

4:30 PM - 5:15 PM HST

Location: Exhibit Hall 3

Presenting author(s)

RJ

Ramon Jaime, PhD

Project Scientist
University of California, Davis
Parlier, California, United States

Author(s)

JL

John S. Lake

Research Assistant
University of California, Davis
Parlier, California, United States
AP

Apostolis Papagelis

Visisting Scientist
University of California, Davis
Parlier, California, United States
RJ

Ramon Jaime-Frias

Lab Assistant
University of California, Davis
Parlier, California, United States
AB

Anais Bannholtzer

Lab Assistant
University of California, Davis
Parlier, California, United States
HL

Hugo Lafon

Lab Assistant
University of California, Davis
Parlier, California, United States
VG

Victor M. Gabri

Research Associate
University of California, Davis
Parlier, California, United States
TM

Themis J. Michailides

Professor
University of California, Davis
Parlier, California, United States

Abstract Text: Aflatoxins are toxic metabolites produced by fungi in Aspergillus section Flavi. Aflatoxin contamination of tree nuts and dry figs is an economic threat to these industries in California. The only effective method of aflatoxin control is the use of atoxigenic A. flavus to displace aflatoxigenic strains. The biocontrol products A. flavus AF36 Prevail and Afla-Guard are used commercially in these crops; however, they have not yet reached their full potential in California. Treating all susceptible crops in area-wide bases can reduce external toxigenic strains and increase efficacy. The study objective was to evaluate the efficacy of the biocontrols A. flavus AF36 and Afla-Guard on area-wide applications. The biocontrols were tested in 5 locations where pistachio, and almond or fig are grown adjacently. Each location consisted of treated (treating all orchards) and non-treated (treating only pistachios) areas. Soil samples were taken before applying the biocontrols and after harvest, and aflatoxin-producing fungi were isolated and classified as A. flavus AF36, Afla-Guard strain, or toxigenic by PCR. Results showed that the treated areas had significantly higher incidence of the applied biocontrol (AF36 or Afla-Guard) and lower incidence of toxigenic isolates than the non-treated areas in all locations. Almonds from the non-treated areas had the highest incidence of toxigenic isolates, while figs from the treated area had the lowest. The incidence of toxigenic strains in pistachios was significantly lower in the treated areas (14%) compared to the non-treated areas (36%)