Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2010
Publication Date: 6/1/2010
Citation: Bruns, H.A., Abbas, H.K. Aflatoxin Contamination in Corn Differs Among Inoculation Techniques. Plant Health Progress, Published on-line - DOI:10.1094/PHP-2010-0601-01-RS. Interpretive Summary: Four methods of inoculating developing corn ears with Aspergillus flavus to produce aflatoxin contamination were examined at Stoneville, MS for three years. Two involved wounding kernels and infecting them with the fungus (a pin bar or side needle injection), one involved spraying fungal spores over the ears, and one used killed wheat seed infected with the fungus spread on the ground between the corn rows. All four techniques produced varying degrees of aflatoxin contamination two of the three years. Weather conditions the final year of the experiment were ideal for corn production and aflatoxin, even on inoculated ears was extremely low, proving further that aflatoxin contamination corn is dependent on heat and drought stress.
Technical Abstract: Aflatoxin in corn (Zea mays L.) is dependent on heat and drought stress during to contaminate the grain. Two experiments, one comparing pin-bar vs. side needle inoculation and the other comparing spraying vs. solid material inoculation were conducted at Stoneville, MS in 2004, 2006, and 2007. Both experiments included non-inoculated control treatments, planted on a silty clay soil in randomized complete block designs replicated 4 times, and furrow irrigated. Plots consisted of six 76 cm rows 9 m long and consisted of an inoculation treatment and one of three commercial hybrids. Inoculated ears from the pin-bar, side needle, and spray treatments were harvested at maturity and analyzed for aflatoxin. The remainder of the experiments were harvested for yield and sampled for analysis of grain moisture, bulk density, kernel weight, aflatoxin, and fumonisin. Rain and irrigation in 2007 were more evenly distributed than in 2004 or 2006, nor were temperatures > 35 C resulting in virtually no aflatoxin and high yields (13.8 Mg ha-1 vs. 7.9 Mg ha-1 and 10.6 Mg ha-1 for 2004 and 2006 respectively). Pin-bar inoculation resulted in higher aflatoxin contamination in 2004 (471.0 ng g-1) and 2006 (239.8 ng g-1) over side needle inoculation (288.5 ng g-1 and 93.2 ng g-1 for 2004 and 2006, respectively), which was greater than plots with no inoculation (14.4 ng g-1 and 5.8 ng g-1 for 2004 and 2006 respectively). Both spray and solid material inoculation did not differ from non-inoculated controls in aflatoxin contamination within each year, though sprayed treatments were less (35.0 ng g-1) in 2006 than (169.7 ng g-1) in 2004.