Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 3/10/2007
Publication Date: 7/28/2007
Citation: Abbas, H.K., Accinelli, C., Zablotowicz, R.M., Abel, C.A., Bruns, H.A., Dong, Y., Shier, W.T. 2007. The Occurrence of Mycotoxins in Corn (Maize) Plant Debris. Phytopathology. 97:7S1
Technical Abstract: Mycotoxins produced by Aspergillus and Fusarium spp. when present in corn, can cause serious toxicological problems in animals and humans. Little is known about their occurrence in crop residue post-harvest. This study determined naturally occurring aflatoxin, fumonisin, and zearalenone (F-2) levels in leaves/stalks, cobs, and grain remaining on cobs left on the soil surface three months after harvest. Isolines Pioneer 34B23 and 34B24Bt were planted in Elizabeth, MS in 2006 using a randomized complete block design with five replicates. Samples were dried, ground and analyzed for aflatoxin, fumonisin, and F-2. At harvest, grain from 34B24Bt corn contained (P less than or equal to 0.05) less total aflatoxin than 34B23 (109 versus 200 ppb, respectively). In vegetative residues less than 4 ppb aflatoxin was observed in both hybrids, but significantly higher aflatoxin levels (P less than or equal to 0.01) were found in cobs (64 ppb) and cobs containing grain (658 ppb) with no differences between Bt and non-Bt corn. Fumonisin averaged 3 ppm in leaf/stem residue, versus 12 ppm in cobs, and 120 ppm in cobs with grain, with no difference between hybrids. In contrast, higher level of F-2 (P less than or equal to 0.01) was observed in vegetative and cob residues (1.8 ppm) compared to cobs with grain (0.2 ppm). The highest colony forming units of A. flavus were recovered from cobs with grain compared to cobs or leaf and stalk residues (log 5.7, log 5.3 and log 3.8 / g, respectively). High levels of mycotoxins in corn residues may endanger wildlife, maintenance of A. flavus propagules may serve as an inoculum for next year’s crop, especially as more growers adopt no-till practices.