Plant traits, growth stage, and ash mass load control the vulnerability of potato, corn, and wheat crops to volcanic ashfall

Current predictive models of ash impact on crops use ash thickness (or mass load) as the explanatory variable but fail to account for other factors, such as plant traits and growth stage, which also influence impact. We conducted a plot experiment with three common crops (potatoes, corn, and wheat), exposing them to representative ash mass loads (0.5 to 9 kg m−2 ). We recorded visual impacts on the plants at different intervals and estimated yield loss. Distinct impact mechanisms were identified for each crop, including premature flower abscission, irreversible leaf yellowing, desiccation and senescence, and stalk lodging. Exposure of potato, corn, and wheat plants to ash mass loads >1 kg m−2 significantly reduced yield, but production quality was largely unaffected. These results were used to develop new vulnerability functions for estimating yield loss in potatoes, corn, and wheat following exposure to an ashfall event.