Fig. 4.

Relationship between disease severity in winter wheat cultivars and the number of days with a soil temperature range of − 0.5 °C to 0.5 °C. Plot colors represent different treatments (black: control (Cont); blue: snow compaction completed within 20 days after the first snowpack (SC1); orange: intermittent snow compaction until 15 Feb (SC2); white: snow removal (Rem)) over 3 years for (a) TY, (b) OG, and (c) PR. Varietal differences are shown in the form of plots. Square, triangle, and circle plots indicate ‘Kunpuu,’ ‘Natsuchikara,’ and ‘Natupirika’ in TY; ‘Esajiman,’ ‘Harujiman,’ and ‘Toyomidori’ in OG; and ‘Tinita,’ ‘Poroko,’ and ‘Doto 1’ in PR.