Efficacy of three antifungal chemicals on the growth in vitro of Aspergillus ochraceus and Aspergillus carbonarius strains isolated from Spanish barley

Barley, the fourth largest cultivated cereal crop in the world is a nutritious cereal. Some moulds can produce great losses in barley crops and synthesize hazardous mycotoxins. Ochratoxin A is, perhaps, the most concerning mycotoxin at present and can be produced by Aspergillus carbonarius and A. ochraceus. Application of chemical fungicides is the most Widely used strategy to control fungal infection in cereal crops. A study on the application of fungicides mancozeb, copper oxychloride and sulphur on the growth of ochratoxigenic strains of A. carbonarius and A. ochraceus was performed. Lag phases and growth rates for two strains of these species in barley -meal extract agar were measured for each fungicide at 15 degrees C and 25 degrees C. The efficacy order was mancozeb > copper oxychloride > sulphur. Response to each chemical depended on the dose and temperature. Effectiveness was higher at 15 degrees C than at 25 degrees C. Mancozeb inhibited fungal growth at 40 mg/l and provided lag phases > 24 days at lower doses. Copper oxychloride at 0.7 g/l at 15 degrees C produced lag phases > 12 days but at 25 degrees C it did not delay fungal growth. Sulphur provided large lag phases at 3-8 g/l at 15 degrees C while at 25 degrees C growth was unaffected up to 8 g/l.