Delivery systems for biological control agents to manage aflatoxin contamination of pre-harvest maize.
While soil application of a competitive non-toxigenic Aspergillus flavus strains is successful in reducing aflatoxin contamination in certain crops, direct application to aerial reproductive structures could be more effective for maize. A sprayable, clay-based water-dispersible granule formulation was developed to deliver non-toxigenic A. flavus strain K49 directly to maize ears. The efficacy of the K49 water-dispersible granule in mitigating aflatoxin in maize (Zea mays L.) was evaluated. Field studies were conducted to compare K49 colonization and effectiveness in reducing aflatoxin contamination when applied either as a soil inoculant or as a directed spray in plots infested with toxigenic strain F3W4. Fifty percent of non-toxigenic A. flavus was recovered from non-treated controls and from plots soil inoculated with K49 on wheat. In spray treatments with formulated or unformulated K49 conidia, over 90% of A. flavus recovered was non-toxigenic. Soil-applied K49 reduced aflatoxin contamination by 65% and spray applications reduced contamination by 97%. These findings suggest direct spray application of non-toxigenic A. flavus strains may be better than soil inoculation at controlling maize aflatoxin contamination and that a water-dispersible granule is a viable delivery system for maintaining viability and efficacy of the biological control agent, K49.
Lyn
M E
ME
Application & Production Technology Research Unit, US Department of Agriculture, Agricultural Research Service, Stoneville, MS, USA.
Abbas
H K
HK
Zablotowicz
R M
RM
Johnson
B J
BJ
D000348:Aflatoxins / Q000378:metabolism*; D000818:Animals; D001231:Aspergillus flavus / Q000254:growth & development*; D018556:Crops, Agricultural; D005506:Food Contamination / Q000517:prevention & control*; D006801:Humans; D010572:Pest Control, Biological / Q000379:methods*; D003313:Zea mays / Q000737:chemistry* / Q000382:microbiology
D000348:Aflatoxins