1a.Objectives (from AD-416):
Design, develop, and evaluate area-wide approaches to aflatoxin elimination using atoxigenic strains of A. flavus. Research characteristics required of processes and equipment for production of inoculum by grower run organizations. Produce inoculum and assess commercial compatibility and efficacy of the area-wide approach.
1b.Approach (from AD-416):
In consultation with Arizona growers and gins, an area-wide aflatoxin elimination program based on atoxigenic strain technologies will be designed and tested. Inoculum production will be scaled up and equipment designed and modified to permit production of sufficient inoculum for evaluation of an area-wide program. Requirements for the different stages of inoculum production will be empirically determined. The economics of atoxigenic strain based programs will be assessed and area-wide influences of atoxigenic strain applications will be quantified.
Research activities are carried out both at the Arizona Cotton Research & Protection Council (ACRPC) and at the Agricultural Research Service (ARS) laboratories in Tucson, AZ. In 2011, efforts continued to define long-term area-wide influences of multi-year applications to cotton fields in Arizona of the aflatoxin biocontrol agent AF36 (a non-toxin producing fungus). Applications had long-term influences that were of practical value for 3 years extending through crop rotations. The extent of long-term influences was dependent on the location with similar Arizona valleys differing in the extent to which the biocontrol strain survived between seasons. Thousands of isolates of the fungus Aspergillus (A.) flavus were placed into the S and L morphotypes (i.e. with different physical features) and the L morphotype isolates were classified by vegetative compatibility analyses (making those that can fuse vegetatively) as either belonging to the same vegetative compatibility group as AF36 or not. Frequency of the biocontrol agent AF36 on the treated crops in target areas was also monitored in order to determine the extent and consistency of displacement of aflatoxin producing fungi. Work was also extended in development of alternative formulations and field tests on replacing wheat in formulations with sorghum were conducted. These tests were extended into 2012, during which new medium scale production of new formulations were used to allow field tests in commercial cotton. It is hoped that movement to less expensive formulations will permit broader and more consistent treatment of crops in areas with vulnerability to aflatoxin contamination. This is the final year of the project.