STEM AND HEAD REACTION OF WINTER-WHEAT CULTIVARS TO ARTIFICIAL INOCULATION BY MICRODOCHIUM-NIVALE UNDER CONTROLLED ENVIRONMENT AND FIELD CONDITIONS

Experiments to assess variation in the resistance of winter wheat to i nfection by Microdochium nivale were conducted over two consecutive ye ars. Resistance was evaluated using an agar disk technique to reproduc e stem lesions and by spraying a conidial suspension to reproduce head blight symptoms. Significant variation for stem reaction measured as stem lesion area (SLA), and head reaction measured as disease severity (DS) was found in the 33 winter wheat genotypes tested. Data obtained over two years in controlled environment conditions were significantl y correlated (r=0.713 for SLA and r=0.738 for DS), whereas field data showed a significant genotype x year interaction for disease severity. Quantitative variation for susceptibility to stem and head infection by M. nivale was found among the 33 genotypes tested. The majority of genotypes expressed moderate susceptibility, with cultivar Goupil bein g very susceptible to both stem and head infection, and the remainder, Renan, Arminda, Munstertaler and Saint-Johann were the most resistant . Resistance to stem and head to M. nivale were not correlated (r=0.35 8).