Although corn is grown throughout the United States, it's the predominant crop of the Heartland region, which includes the states of Illinois, Iowa, Indiana, and parts of South Dakota, Nebraska, Kentucky, Ohio and Missouri. According to the U.S. Department of Agriculture, the United States is the world’s largest producer of corn, with about 80 million acres of land used for corn cultivation. However, a common problem faced by corn producers is the loss of crop due to contamination of corn by fungi. These fungi produce toxins, called mycotoxins, which can cause serious illness in humans and livestock.
Fungal Contamination of Corn
Most of the conditions that favor the growth of fungi on corn are associated with climate. These include temperatures ranging from 80 to 100 degrees F, and a relative humidity of 85 percent. Other factors include drought stress, rainfall, nitrogen availability and damage of the corn by insects. Although several species of fungi contaminate corn and produce different mycotoxins, two of the most common types found in contaminated corn are aflatoxins and fumonisins.
Aflatoxins in Contaminated Corn
Aspergillus flavus is a common fungus that thrives in a hot and dry climate, and appears as a yellow- to dark yellow-green mold on corn. Aflatoxin, the mycotoxin produced by Aspergillus flavus in corn, is a liver carcinogen and acute exposure to humans can be fatal. A 2008 article in the Science Daily reports of human deaths caused by consumption of aflatoxin-contaminated corn in Kenya. Aflatoxins are also linked to poor growth and immune function in West African children, according to Robert L. Brown of the USDA. In animals fed contaminated corn, aflatoxins cause symptoms of liver necrosis and tumors, as well as diminished growth and poor immunity.
Fumonisins in Contaminated Corn
Another fungi, Fusarium moniliforme, commonly contaminates corn and produces the mycotoxin fumonisin in corn. Corn kernels contaminated by this fungus may appear normal, as the white or pink colored mold isn't always apparent. However, consuming this contaminated corn may have serious consequences; the fumonisin produced by this fungus has been linked to esophageal cancer in humans. Furthermore, a 2010 study reported in the journal of "Molecular Nutrition and Food Research" found that Tanzanian infants consuming maize diets containing high levels of fumonisin had stunted growth and were underweight. In animals, fumonisin from contaminated corn feed has been associated with equine leukoencephalomalacia in horses and porcine edema in pigs.
Minimizing Mycotoxin Contamination in Corn
North Carolina State University lists several precautions that can minimize contamination of corn with fungi that produce deadly mycotoxins. Some of these include drying and storing the corn in a clean storage facility where the moisture content is less than 13 percent. This will prevent the growth of common fungi species Aspergillus flavus and Fusarium moniliforme. Timely irrigation practices can reduce drought stress that is favorable for aflatoxin production. Farmers should plant and harvest their crop early, prevent insects from damaging crops and try to keep kernels intact during harvest.
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