Phoma stem canker (Leptosphaeria maculans/L. biglobosa) of oilseed rape (Brassica napus): is the G₂ Disease Index a good indicator of the distribution of observed canker severities
2009
Lô-Pelzer, E. | Aubertot J.N. | Bousset, L. | Pinochet, X. | Jeuffroy M.H.
Several disease indices (DI) have been proposed to assess the severity of phoma stem canker at late growth stages. The DI commonly used in France (called G₂ DI) consists of integrating the distribution of the proportions of plants observed within six canker severity classes into a single index. This index uses arbitrarily chosen coefficients associated to each class of canker severity. A given value of this DI can therefore be obtained with different distributions among the canker severity classes. Consequently, it is important to assess to what extent the G₂ DI is representative of the distribution of plants in canker severity classes. We show in this study that the G₂ DI is a good indicator of the distribution of the observed canker severities, using a dataset from different years, sites and cultivars; this illustrates the robustness of the G₂ DI.
显示更多 [+] 显示较少 [-]