Greenhouse-grown genotypes were separated into mild, moderate, and severe symptom groups based on leaf mottling, color, and size. In general, mild symptom genotypes were characterized by increased photosystem II (PSII) excitation pressure and unregulated heat dissipation and decreased regulated heat dissipation, whereas moderate and severe symptom genotypes increased loss of photosynthetic efficiency and increased unregulated and regulated heat dissipation. Distant asymptomatic leaves could be distinguished from healthy ones in moderate and severe symptom genotypes by increased total and regulated heat dissipation measurements.