The presence of mycotoxins and fungi in rice and corn in the southern United States.

[Synopsis] Fumonisins (≦4.3 ppm) were measured in rice (Oryze sativa L.) samples naturally infected with Fusarium sheath rot disease associated with F. proliferatum. F. proliferatum cultures isolated from these samples produced fumonisins (≦230μ g/g), moniliformin (≦6018 μ g/g), and beauvericin (≦1350 μ g/g). Deoxynivalenol (DON, vomitoxin), and zearalenone (ZEA, F-2) were detected in 94 and 77 respectively, of 100 Fusarium rice scab samples from Arkansas in 1996, at≦ 1.6 μ g/g and 2.2μ g/g. Aflatoxins and fumonisins were found in 10 and 5 of 100 Fusarium rice scab samples, at ≦ 28.6 ng/g and 500 ng/g, respectively. F. graminearum cultures were isolated and representative cultures (10) produced DON and its derivatives ≦ 430μg/g and zearalenone atc 9,883 μ g/g. False smut in rice caused by Ustilaginoidea virens produced a water-soluble compound that was found to be phytotoxic to duckweed (Lemna pausicostata L.), but not cytotoxic to mammalian cell lines at 200 μ g/g. In 1998, major aflatoxin contamination occurred in corn in the southern USA. Over 300 corn samples from 77 different hybrids were analyzed and at least 86％ of the samples had 20 ng/g aflatoxins or higher (4 to 2,506 ng/g). All the samples contained fumonisins (1.2 to 47 μ g/g). Deoxynivalenol was detected in some of these samples, but not zearalenone. In summary, we have observed DON, zearalenone, fumonisins and aflatoxins, and the fungi that produce them on rice and corn. The toxins are present at levels that are of concern for food safety.