Effect of spring barley protection on the production of Fusarium spp. mycotoxins in grain and malt using fungicides in field trials

The effects of different fungicides in four-year trials with a susceptible variety of spring barley, which was grown in field conditions with two previous crops (sugar beet and corn) and artificially inoculated with spores of Fusarium, were investigated. Field trials were laid down in plots of the Agricultural Research Institute Kromeriz, Ltd. (235 m above sea level, average annual temperature 8.7degreesC, annual precipitation sum 599 mm) in 2000-2003. The variety Kompakt, which was very sensitive to Fusarium head blight (FHB) in other trials, was used in all the trials examined. Incidence and severity of FHB and control with fungicides were measured by deoxynivalenol (DON) contamination of grain and malt. The content of Fusarium trichothecenes was evaluated in one fraction of kernels (diameter 2.5 mm) which is used in malting technology process. In 2000 and 2001, the treatments without adjuvants were applied. In the following two years, Silwet L-77 adjuvant (0.1 1/ha) was used with different rates of water (250 and 150 1/ha in 2002 and 2003, respectively). In all years, DON content increased in most cases after the grain samples were malted. The conditions of high grain moisture, moderate temperature and high relative humidity provide an ideal environment for Fusarium growth during germination. The greatest reduction of mycotoxins was achieved using a combination of azole fungicides with tebuconazole or metconazole or a mixture of metconazole + famoxadone + flusilazole with the addition of Silwet L-77 and a low rate of water.