Effect of Planting Density and Planting Date On Corn Aflatoxin Contamination.

Corn aflatoxin contamination is a major problem in the Southeast US. The lack of rainfall and high temperature in coarse-textured soil areas have been identified as conditions inducing corn aflatoxin contamination in the region. Identification of management strategies that can minimize the impact of weather-related aflatoxin infection could help farmers in reducing the risk of contamination. A study on the effect of planting density and planting date on corn aflatoxin level is being conducted on the coastal plain region of Alabama. The study had a split-split plot design with two field inoculation treatments (i.e. inoculated and non-inoculated) of Aspergilus flavus, two planting dates and three planting densities (18,000, 22,000, and 26,000 plants/acre) with six replications. The corn plots were planted in mid-March (first planting date) while the second set was planted one month later. For each planting date, inoculation of Aspergilus flavus was done at silking stage. At harvest, ten corn ears were randomly sampled from each plot and tested for aflatoxin level (parts per billion, ppb) using Enzyme-linked immunosorbent assay (ELISA) technique. Based on the summer 2010 preliminary results, inoculated plots had higher aflatoxin content compared to the non-inoculated plots. Aflatoxin levels increased as the planting density increased and planting was delayed. For the first planting date, there was an increase in aflatoxin contamination with increased planting density on both inoculated and non-inoculated plots. Conversely, there was no a clear trend of variation between aflatoxin level and planting density on the second planting date which could be explained by confounding effects such as insect infestation. This study showed that management strategies such as planting date and planting density could be modified to reduce pre-harvest aflatoxin risk.