Infection category | Grading of witches’ broom disease at individual level | Grading of witches’ broom disease at branch level | Value/Score |
---|---|---|---|
Level 1 | No observable infection | No observable infection | 0 |
Level 2 | The % of infected branches to the total was < 25% | The twig grows in an acropetal sequence with very thin stems and little leaves, but only for single twig without cluster phenomenon | 1 |
Level 3 | The % of infected branches to the total was 26–50% | The lateral buds grew out, several lateral branches clustered together, and the smaller leaves were not withering | 2 |
Level 4 | The % of infected branches to the total was 51–75% | The lateral buds repeatedly grew out with distributed small clumps, and the smaller leaves either withered or fell off | 3 |
Level 5 | The % of infected branches to the total was > 75% | The lateral buds repeatedly grew out with comprehensively distributed clumps of the culm | 4 |