Reaction of winter wheat varieties to Fusarium graminearum and F. culmorum in field infection trials and the efficacy of fungicides

Fifteen winter wheat varieties were tested for their reaction to Fusarium culmorum and F. graminearum in the ear in 1996, 1998 and 1999. To ensure a sufficient level of infection in the field the varieties were artificially inoculated with spores of the two species at a ratio of 1:1. The infection was evaluated using a 10-score scale at three times: first at the milk stage (BBCH 71-75), i.e. about 14 days after inoculation; two further readings were taken at 7-day intervals. The data were used to calculate the average infection for each variety at each reading, and were statistically evaluated. The parameter "area under disease progress curve" (AUDPC) was also calculated. Significant differences between varieties were found in all investigated years. On the average of the 3 years, the variety Ebi showed the lowest infection. Other varieties with significantly low infection were Estica and Atlet. The variety with the highest infection was Bruneta, followed by Samanta, Saskia and Samara. The degree of infection was considerably influenced by weather conditions in the year. A lower infection was observed in 1996 when rainfall in the period from 1st to 20th June was below normal, while rainfalls in 1998 and 1999 were higher in this period. The efficacy of fungicides was assessed in the highly susceptible variety Bruneta. All tested preparations significantly decreased the degree of infection in comparison with the untreated control. In 1998 the efficacy of fungicides was rather low (from 15.51 to 37.55%), while in 1999 it was higher (from 36.74 to 58.20%). In both years the preparation Folicur BT was most efficacious.