Temperature-Sensitive Reaction of Winter Wheat Cultivar AGSECO 7853 to Stagonospora nodorum.

Stagonospora blotch is an important foliar and head disease of wheat (Triticum aestivum) in many regions of the world. To determine the reaction of winter wheat cultivars to Stagonospora blotch at different temperatures, seedlings of the hard winter wheat cvs. Newton, AGSECO 7853, and Heyne were inoculated with three isolates of Stagonospora nodorum and exposed to three temperature regimes (high, 29 and 21°C [day and night]; medium, 25 and 17°C; and low, 18 and 10°C). Heyne was resistant at all temperatures in all three experiments. The reaction of AGSECO 7853, when averaged over all isolates, was intermediate between Heyne and Newton at high temperature, as susceptible as Newton at medium temperature, but more susceptible than Newton at low temperature. Therefore, the reaction of AGSECO 7853 relative to Newton was temperature sensitive. This finding is important in the evaluation of wheat lines for resistance to Stagonospora blotch because the relative ranking of one cultivar may differ from another depending upon the temperature.