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Grading standard for the strength of resistance∗.
| Resistance grade | Resistance response | Damage index range (dead hearts) % |
|---|---|---|
| 0 | Highly Resistant(HR) | 0 |
| 1 | Resistant(R) | 1–20 |
| 3 | Moderately Resistance (MR) | 21–40 |
| 5 | Endurance (E) | 41–60 |
| 7 | Susceptible (S) | 61–80 |
| 9 | Highly susceptible (HS) | ≥81 |
∗Grading standard of resistance refers to Pathak et al. (1971).
