Mycotoxins and toxigenic fungi in insect-damaged maize harvested during 1983 in far North Queensland

Abstract

A survey for mycotoxins and toxigenic fungi in maize (Zea mays) grown during 1983 in Far North Queensland is reported. Zearalenone was detected in 148 of the 174 samples examined. Low concentrations of aflatoxins were detected in three of the samples. Ochratoxin A, sterigmatocystin, T-2 toxin and deoxynivalenol were not detected. The 1983 season was unusual in that plants were stressed from low rainfall in the early stage of growth. Insect damage, mainly by ear worms (Heliothis sp.), was severe. Despite this, there was no significant increase in zearalenone concentrations compared to a previous survey in 1982, when insect damage was minimal. Ten samples were used for fungal isolations. Fusarium moniliforme was the most frequently isolated fungus, and its isolation frequency increased in visibly damaged kernels. F. graminearum was most frequently isolated from kernels with a purple discoloration. The correlation between the isolation frequency of F. graminearum and zearalenone concentrations indicated that F. graminearum produced most of the zearalenone in the samples. Other fungi isolated included F. subglutinans, F. oxysporum, Aspergillus jlavus, A. niger, Penicillium sp., Trichoderma sp., Nigrospora sp., Curvularia sp., Drechslera sp., Acremonium zeae and Rhizoctonia sp.