Determining Future Aflatoxin Contamination Risk Scenarios for Corn in Southern Georgia, USA using Spatio-temporal Modelling and Future Climate Simulations

Mycotoxins are toxins produced by fungi which are harmful to humans and animals and can contaminate staple crops. Aflatoxins are particularly toxic and can cause liver cancer so the permitted levels in foodstuffs are legislated. Batches of grain where average aflatoxin concentrations are higher than legislative thresholds are rejected or sold at a lesser price for a more limited range of use. High maximum temperatures and low rainfall have been shown to increase contamination. For corn grown in Southern Georgia, USA, June weather is particularly important as this coincides with the sensitive mid-silk growth stage. An AFs survey and weather data have been used to show the association between AFs and June weather [1]. The risk factors were June maximum temperatures >33˚C and June rainfall <50mm, the 30-year normals 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 weather risk factors were calculated. The number of counties with June maximum temperatures >33˚C and rainfall <50mm increased significantly between 30-year time periods. The percentage of years that counties exceeded thresholds was greater for the RCP 8.5 than the RCP 4.5 scenario. A change in the spatial distribution of high-risk counties was seen over time. The results suggest the need for changes in the where crops are grown or the employment of adaptation strategies such as planting more resistant varieties, improving irrigation and planting earlier to avoid increasingly frequent rejection of grain batches. There were significantly more counties with June maximum temperatures >33˚C and June rainfall <50mm in 2010-2040 compared to 2000-2030. This suggests that adaptation strategies should be employed as soon as possible.