Snow manipulation: Adaptability and limitations of physical control of snow mold and frost damage in pastures

Background and Aims : Soil temperature regulation through snow manipulation can mitigate overwintering diseases and enhance pasture growth. Identifying optimal temperature conditions for healthy overwintering is crucial, particularly in cold-resistant species such as timothy (TY). This study evaluated the effects of snow manipulation on overwintering damage and disease control in TY, orchardgrass (OG), and perennial ryegrass (PR). Methods : Snow manipulation was applied to pasture plots, and its impact on soil temperature and disease severity was assessed. The metric Mild-T, representing the number of days with soil temperatures near 0°C, was analyzed to determine its role in thermal disease control. Disease severity and total overwintering damage were compared across species. Results : Snow manipulation reduced Mild-T, which correlated with lower disease severity, particularly in TY. In plots with < 20 consecutive Mild-T days, maximum disease severity was the lowest in TY (0.13) compared to OG (1.78) and PR (1.63). However, total overwintering damage was influenced by disease and frost resistance. Although snow mold reduction did not consistently decrease overall damage, PR exhibited severe frost damage, making it highly vulnerable to snow manipulation. Contrastingly, OG compensated for overwintering losses because of its strong regrowth ability, maintaining similar dry matter production. Conclusion : Snow manipulation effectively controls overwintering diseases but may increase frost damage in less cold-resistant species. TY demonstrated the greatest adaptability, while PR showed high susceptibility to frost injury. OG maintained productivity despite overwinter losses. The findings highlight the need to consider disease and frost resistance when applying snow manipulation as a disease control strategy.