Potential Aflatoxin and Fumonisin Contamination in Maize Hybrids with Various Ear Formation Properties.

Experiments were conducted at Jonesville, LA in 2000 and at St. Joseph, LA in 2001-2003 to compare three corn (maize, Zea mays L.) hybrids (a fixed-ear hybrid, Pioneer 33K81; a semi-fixed ear hybrid, Pioneer 3223; and a flex-ear hybrid; Golden Acres 8460) and to determine the effect of irrigation on aflatoxin and fumonisin contamination of harvested grain under standard husbandry conditions or when inoculated with Aspergillus flavus by the pin-bar inoculation technique.  Non-irrigated plots were compared with plots administered furrow-irrigation scheduled using the Arkansas Irrigation Model at a 38 mm and a 63.5 mm soil moisture deficit (SMD).  Average aflatoxin levels from natural infection ranged from 23 ng/g with 38 mm SMD to 41 ng/g with 63.5 mm SMD.  Significantly greater aflatoxin levels occurred in 2002 in the flex-ear hybrid.  In corn inoculated with A. flavus, significantly more aflatoxin contamination also occurred in flex-ear hybrid grain compared to other hybrids in 2001, with no significant effect of irrigation.  Levels of fumonisin contamination in grain from uninoculated hybrids were greatest in the flex-ear hybrid in 2003, with the highest fumonisin levels under well-irrigated conditions in two of the three years.  In corn inoculated with A. flavus, the highest level of fumonisin contamination was found in flex-ear hybrid grain in all three years with no consistent effect of irrigation.  Under the conditions used, the flex-ear hybrid was most susceptible to both aflatoxin and fumonisin contamination with no consistent effect of irrigation.