Fusarium toxins in field corn. I. Time course of fungal growth and production of deoxynivalenol and other mycotoxins

Abstract

The formation of the trichothecene mycotoxins deoxynivalenol and 15-acetyldeoxynivalenol and zearalenone in field corn inoculated with Fusarium graminearum was studied over a growing season. The mycotoxins, ergosterol, colony forming units, weight, moisture, and ash contents were measured in the infected ears. Measurements of toxins and ergosterol in infected plants, weather data, and analyses of the soil mycoflora were also taken. In the infected ears, fungal propagule counts rapidly increased up to 6 weeks after inoculation and then sharply declined. Ergosterol concentrations followed the propagule data for the first 6 weeks and then levelled off (at about 70 ppm). Deoxynivalenol concentrations increased (to about 580 ppm), over the same period and then declined (to about 430 ppm); 15-acetyldeoxynivalenol concentrations rose rapidly in the first 2 weeks (to 64 ppm) and then slowly declined (to 20 ppm); an appreciable amount of zearalenone (10 ppm) was not observed until 9 weeks after inoculation. The data indicated that the relative and absolute concentrations of the two trichothecenes present in the corn may have been affected by the plant, and toxins were found throughout the plant but mainly in the infected part.