Fusarium graminearum, the dangerous fungus smuggled by two Chinese nationals into the US, infects cereal crops like wheat, barley, oats, and corn by causing a disease known as fusarium head blight. It produces toxins such as deoxynivalenol and zearalenone, which can contaminate grains. The toxins pose health risks to humans and animals, including vomiting, liver damage, and reproductive issues.