Location: Crop Protection and Management ResearchTitle: Effect of ENSO on Corn Aflatoxin in South Georgia) Author
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/24/2011
Publication Date: 5/24/2011
Citation: Salvacion, A., Ortiz, B., Scully, B.T., Wilson, D., Hoogenboom, G., Lee, R. 2011. Effect of ENSO on Corn Aflatoxin in South Georgia. Meeting Abstract. Climate Information for Managing Risks. May 24-27, 2011. Orlando, Florida. Interpretive Summary:
Technical Abstract: The El Niño Southern Oscillation (ENSO) is associated with climate variability around the world, and is known to adversely affect food production systems. In the Southeastern US, research has shown that ENSO influences crop production. Two multivariate ENSO Indices, MEI and Niño 3.4, are typically used to categorize ENSO events as El Niño, La Niña, and Neutral. MEI uses observed variables including: sea level pressure, surface zonal wind, meridional wind, sea surface temperature, surface temperature, and cloudiness over the tropical Pacific, while the Niño 3.4 model uses monthly sea surface temperature departures from the long-term mean averaged over the Niño 3.4 region. This research attempts to establish a link between ENSO and corn aflatoxin contamination in the Southeastern US using available records from a long-term USDA-ARS corn aflatoxin survey along with historical weather data from 21 sites in southern Georgia, and the MEI and Niño 3.4 indices. Specifically, weather variables such as rainfall and maximum temperature during the critical corn grain-fill stage for aflatoxin contamination were examined and differed by ENSO phase in southern Georgia. As expected, lower rainfall, and higher than normal temperatures during corn reproductive stage increased the likelihood of aflatoxin contamination. These analyses confirmed known relationships between corn aflatoxin contamination and deviations from average rainfall (p-value = 0.032) and maximum temperature (p-value<0.0001). In southern Georgia, ENSO phases were not predictive of rainfall deviation using either MEI (p-value= 0.95) or Niño 3.4 (pvalue=0.17) indices, but both indices were predictive maximum temperature deviations (MEI p-value<0.0001 and Niño 3.4 p-value=0.03). With both ENSO indices, El Niño years consistently produced lower maximum temperature deviations compared to Neutral years. The predicted probability of aflatoxin levels above the critical 20ppb contamination threshold differed significantly by ENSO classification. When the MEI index was used, significantly higher probabilities of contamination were observed during Neutral years, while higher probabilities were also predicted for both La Niña and Neutral year using Niño 3.4 index. In contrast, El Niño years indicated a significantly lower likelihood of contamination above the 20 ppb threshold compared to La Niña and Neutral years, when evaluated by both models . In summary, the probability of aflatoxin contamination is highly associated with deviation of maximum temperature from historic average values. Although a higher deviations from the normals differed by ENSO index; consistently lower temperatures were observed during an El Niño phase and indicated lower level of aflatoxin contamination. This preliminary investigation may provide a novel and simple approach for alert and risk assessment of aflatoxin contamination in southern Georgia based on monthly rainfall and maximum temperature as well as ENSO forecast.