Submitted to: Phytoparasitica
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/10/2007
Publication Date: 6/1/2007
Citation: Windham, G.L., Williams, W.P. 2007. Effect of ear bagging systems on Aspergillus flavus kernel infection and aflatoxin contamination of corn hybrids grown in the field. Phytoparasitica. 35:277-281. Interpretive Summary: Aflatoxin is a cancer causing toxin produced by the fungus Aspergillus flavus in corn grain while still in the field. This disease is difficult to work with because aflatoxin production is highly dependent on high temperatures and drought stress conditions. By changing the environment surrounding the ear, it might be possible to manipulate aflatoxin contamination and disease production. We initiated studies to determine the effect of different bagging systems on disease development in corn ears. Studies were conducted in a sandy field prone to drought stress and in a field with high clay content that had limited amounts of water stress. In the first study, ears inoculated with the fungus, Aspergillus flavus, were covered with either black or white paper bags. In a second study, ears were covered with brown paper bags or clear plastic zip-lock bags after inoculation with the fungus. Daily average temperatures increased 2 to 4 degrees F inside the bags. Temperatures inside the plastic bags were as high as 120 to 130 degrees F. Bagging the ears had little effect on aflatoxin production or fungal infection. More of an effect by the bagging systems was seen in the sandy field. Environmental conditions such as temperature and drought stress must interact to trigger aflatoxin production in developing ears in the field.
Technical Abstract: Field studies were conducted for 4 years in Mississippi to determine the effect of various ear bagging systems on Aspergillus flavus kernel infection and aflatoxin production in developing ears of corn hybrids. Each year, three corn hybrids were grown on Myatt loam (low water-holding capacity) and a Leeper silty clay loam (high water-holding capacity). Corn ears were inoculated with A. flavus using the side-needle technique 7 days after midsilk (50% of the plants in the plot had silks emerged). For the first two years, inoculated ears were covered with either white or black paper pollination bags at approximately 14 days after inoculation. During the last two years, inoculated ears were covered with either a brown paper pollination bag or a clear plastic zip-lock bag. Daily mean temperatures were increased 1 to 2 degrees C in all of the bagging systems over ambient temperatures. The bagging systems had a limited effect on aflatoxin production or A. flavus kernel infection.