LAUSR

Fungicide application facilitates seed and seedling survival, but these pesticides may also negatively affect germination. Moreover, it is unclear how fungicide may interact with influential environmental conditions, such as cold stratification, to affect tree seed germination. We examined how fungicide and five different cold stratification durations of increasing length influenced tree seed germination (i.e., germination fraction and germination rate) for five important species commonly found in temperate North American forests (Abies balsamea, Acer saccharum, Picea glauca, Pinus resinosa, and Pinus strobus). Greater cold stratification durations increased A. saccharum germination fraction, had positive effects on P. strobus and A. balsamea germination fractions, and decreased germination for P. glauca. Longer cold stratification reduced time to germination for all species, reinforcing the importance of this pregermination condition in tree seed phenology. We also found that although Captan 50W fungicide had no effect on the germination fraction for any species, it delayed the germination of P. glauca and P. strobus at specific stratification durations. We suggest that delays in tree seed germination—mediated by fungicide application, reductions in stratification duration driven by warmer winters, or both— could hinder seedling survival and performance with long-term effects on the vigor of tree seedlings used for transplanting.