Many experts in the UGA College of Agricultural and Environmental Sciences are working to address the global aflatoxin problem in peanuts, including researchers in the Feed the Future Innovation Lab for Peanut, who developed a course to increase basic knowledge of aflatoxin for producers in developing countries.
“Irrigated peanuts are much less likely to have aflatoxin, and Georgia is fortunate in that over half of our total production is from irrigated fields,” said Tim Brenneman, professor of peanut and pecan disease management in the CAES Department of Plant Pathology and a member of the UGA Peanut Team. “The biggest issue by far is in non-irrigated fields, especially in unusually hot, dry years like 2019 when losses were estimated at 24%.”
“UGA is taking a multidisciplinary approach and applying our different areas of expertise to come up with lasting solutions for growers,” said Bob Kemerait, professor and UGA Extension plant pathologist. “Aflatoxin may not be a major problem every year, but the fungus that causes it, Aspergillus flavus, is very common and is present in almost every field, so the potential is always there. While field rotation does work on some diseases, it’s difficult if not impossible to rotate away from Aspergillus flavus. If the conditions are right and we can’t mitigate, the aflatoxin problem will come back.”
The UGA team is exploring several potential methods to control aflatoxin. One option is improving peanut varieties with increased drought tolerance to reduce susceptibility or concentration of aflatoxin in peanuts. Another is control through production strategies such as irrigation, improved detection strategies, and preventing insect or other damage to peanut pods during the growing season.
“A significant area of new research is focused on trying to determine how we can better identify the areas in a field that are more likely to be at a higher risk for aflatoxin, for whatever reason,” Kemerait said. “If we can identify those areas of greater risk, we can apply management strategies to control it or perhaps modify a grower’s harvest plans.”
The team is also exploring the efficacy of biological control methods, such as Afla-Guard, a natural agent that includes a variant of Aspergillus flavus that does not produce aflatoxin. The hope is that the non-toxin-producing strains will outcompete the toxigenic strain of the fungus in the peanut fields, Kemerait said.
Parallel research efforts include improving storage of harvested peanuts to reduce the potential for aflatoxins to proliferate during storage.
“A crop could have low aflatoxin levels going into storage, but if there is too much moisture in the storage area, peanuts that would have been at acceptable levels can develop high levels of aflatoxin,” Kemerait added. “Detection is absolutely essential. If you can detect whether a crop is above threshold levels or at risk for aflatoxin, you want to keep those peanuts away from peanuts with low levels or no aflatoxin. When you store peanuts, you have to store them appropriately so that even low levels of aflatoxin do not proliferate.”
In the peanut industry, much of each year’s harvest is put into storage to provide a steady supply of peanuts for the production demands of end users over the course of the next year. In 2021, Georgia producers harvested more than 3.3 billion pounds of peanuts from 750,000 acres planted, accounting for approximately 52% of the peanuts produced in the U.S. in 2021.
“Peanuts are not a highly perishable crop and can be held up to a year in storage. In a perfect world, you would be able to harvest a crop and sell it quickly, but it takes time for industry to need the volume of peanuts harvested every year,” Kemerait said.
Stringent aflatoxin testing is performed at harvest and throughout the production process to ensure that aflatoxins do not get into the final product.