Which factor does NOT determine a tree's disease resistance?

The growth rate under ideal conditions does not directly influence a tree's disease resistance. While rapid growth can be indicative of a tree's overall vigor and health, it does not inherently provide any protection against diseases or the ability to resist pathogens.

In contrast, the other factors listed contribute significantly to a tree's resistance to disease. The ability to adapt to environmental changes can enhance a tree's resilience, as trees that can manage stressors like drought or soil changes are more likely to fend off diseases. Resistance to specific pathogens is a direct measure of how well a tree can protect itself against particular diseases. Genetic factors also play a crucial role; trees possess inherent genetic traits that can influence their immune responses and overall durability against diseases.

Thus, while rapid growth can be beneficial for overall health and vitality, it is not a determinant of a tree's ability to withstand disease.