Determining future aflatoxin contamination risk scenarios for corn in southern Georgia, USA using spatio-temporal modelling and future climate simulations

Authors: KERRY, RUTH - Brigham Young University; INGRAM, BEN - University Of Talca; GARCIA-CELA, ESTER - University Of Hertfordshire; MAGAN, NARESH - Cranfield University; ORTIZ, BRENDA - Auburn University; Scully, Brian

Submitted to: Nature Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2021
Publication Date: 6/29/2021
Citation: Kerry, R., Ingram, B., Garcia-Cela, E., Magan, N., Ortiz, B.V., Scully, B.T. 2021. Determining future aflatoxin contamination risk scenarios for corn in southern Georgia, USA using spatio-temporal modelling and future climate simulations. Nature Scientific Reports. 11:13522. https://doi.org/10.1038/s41598-021-92557-6.
DOI: https://doi.org/10.1038/s41598-021-92557-6

Interpretive Summary: Corn growers throughout the southern U.S. are keenly aware of aflatoxin contamination of corn grain induced by Asperigillus flavus. In Georgia and the surrounding southern states, aflatoxin contamination is exacerbated by: 1) elevated temperatures (>30 C) in the June silking, pollination and early grain fill stage, and 2) periods of drought (<50 mm rainfall) during this critical phase of crop development. In this research, two "Future Climate Prediction Models" (RCP 4.5 & RCP 8.5) were used to develop scenarios that asses future aflatoxin risk to corn producers in Georgia over 30 year time intervals and for individual counties across the state. These predicative models were built from a 28 year data set (1977-2004) of aflatoxin levels found in corn grain collected annually from 23 to 45 counties in Georgia, and the weather/climatic criteria noted above. Both climate simulation models projected that the aflatoxin contamination of corn will continue to be a risk for the remainder of the 21st century. Both models also predicted that the interval from 2020-2050 would have a higher risk, and the RCP 8.5 model indicated that 2070-2100 would have the highest risk. Geographically, the counties to the northwest of a line that roughly bisects the state from the southwest corner toward the northeast are at significantly higher risk than those counties southeast of this bisect. These results indicate that growers should continue use aflatoxin resistant hybrids as they become available,plant earlier, and consider irrigation systems that help reduce canopy temperatures.

Technical Abstract: Aflatoxins (AFs) are a group of carcinogenic mycotoxins produced by Aspergillus section Flavi species. In southern Georgia (GA), USA contamination levels have been linked to high maximum temperatures and low rainfall during the key mid-silk growth stage which occurs in June in the region. An AFs survey and weather data have been used to show the association between AFs and weather risk factor variables [1]. The risk factors were June maximum temperatures above 30-year normals for the region and June rainfall less than the 30-year normal for the region. Future climate data were estimated for each year (2000-2100) and county in southern GA using the RCP 4.5 and RCP 8.5 emissions scenarios and the weather risk factors calculated. Results showed that the number of counties that exceeded risk factor thresholds for both June maximum temperatures and rainfall increased significantly between 30-year time periods. The percentage of years that counties exceeded thresholds was greater for the RCP 8.5 scenario, and the projected data suggested that the spatial distribution of high-risk counties would change over time. The results suggest the need for adjustments in the current distribution of where crops are grown or the employment of adaptation strategies such as planting more resistant varieties, improving irrigation and planting earlier. The significantly higher proportions of counties exceeding two weather risk factor thresholds in 2010-2040 compared to 2000-2030 suggests that employing adaptation strategies should be initiated as soon as possible.