AGRICULTURAL PRACTICES, ECOLOGICAL AND VARIETAL EFFECTS ON AFLATOXINS AND OTHER MYCOTOXINS IN CORN
Location: Biological Control of Pests Research Unit
Title: Dynamics of Mycotoxin Concentrations in Aging Corn Residues Under Mississippi No-Till Conditions
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 12, 2008
Publication Date: July 22, 2008
Citation: Abbas, H.K., Accinelli, C., Zablotowicz, R.M., Abel, C.A., Bruns, H.A., Dong, Y., Shier, W.T. 2008. Dynamics of Mycotoxin Concentrations in Aging Corn Residues Under Mississippi No-Till Conditions. Journal of Agricultural and Food Chemistry. 56:7578-7585
Interpretive Summary: There are more than 300 mycotoxins produced by molds (Fungi). However, only a few are considered to be dangerous when ingested by animal or humans. These toxins include aflatoxins, fumonisins, and zearalenone. In this research, these three toxins were found in corn grains and in corn residues remaining on the soil surface after harvest. High levels of these toxins in corn residues may have a negative impact on livestock or wildlife grazing on the residues. Therefore, in the corn fields that are infested heavily with fungi that produce these toxic materials, corn residues should not remain on the surface of soil in order to protect the livestock from grazing on residue contaminated with mycotoxins.
Mycotoxins, including aflatoxins, fumonisins, cyclopiazonic acid (CPA), and zearalenone, produced by Aspergillus and Fusarium species when present in grain can cause serious health problems in livestock and humans. Little is known about the occurrence of these toxins in corn plant debris post-harvest. The objective of this study was to determine the over-wintering mycotoxin levels in corn stover, cobs, and cobs containing grain on the soil surface three months after harvest. Isogenic Pioneer hybrids 34B24(Bt) and 34B23 (non-Bt) were planted at Elizabeth, MS in 2006. Samples of grain or residues were dried, ground and analyzed for aflatoxin, fumonisin and CPA. At maturity, grain from Bt hybrid contained significantly less total aflatoxin than the conventional hybrid (109 vs 200 ng g-1). In stover residues, less than 4 ng g-1 aflatoxin was observed in both hybrids. Higher aflatoxin levels were found in cobs (17 to 111 ng g-1) and cobs containing grain (541 to 774 ng g-1), with significantly greater levels in the non-Bt hybrid compared to the Bt hybrid (P > 0.01). Fumonisin levels averaged 3 'g g-1 in stover, 12 'g g-1 in cobs, and 120 'g g-1 in cobs, with grain with no difference between hybrids. The pattern of partitioning of zearalenone in corn residues was different than other mycotoxins in that the lowest concentration was observed in cobs with grain(mean = 0.08 'g g-1 ) compared to cobs (mean = 0.05 'g g-1) or stover (0.67 'g g-1) with no deoxynivalenol (DON) or its derivatives detected in any samples. The distribution of CPA followed a similar trend as aflatoxin and fumonisin. The presence of high levels of these mycotoxins in corn residues could be detrimental to grazing livestock or wildlife.