Decision Support Systems in Agriculture: Administration of Meteorological Data, Use of Geographic Information Systems(GIS) and Validation Methods in Crop Protection Warning Service - Efficient Decision Support Systems: Practice and Challenges from Current to Future - page 346

and the Kolmogorov-Smirnov test mean that the model is considered a statistically accurate
simulator of the field data (Teng, 1981).
SEPTRI is a model able to simulate the disease epidemics of Septoria tritici on winter wheat.
In particular the model calculates the infection probability, the infection rate, the lesion
growth and the sporulation for wheat cultivars for three susceptibility levels: high
susceptible, mean susceptible and low susceptible. The simulation results are the values of
disease severity per leaf layer.
Also this model was validated using both subjective visual method (fig. 8, tab. 7) and
statistical methods (tab. 8).

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21

18

15

12

9

6

3

0

14/05/09 24/05/09 03/06/09 13/06/09 23/06/09 03/07/09

Date

Fig. 8. SEPTRI - Simulated disease severity (DS) on the flag leaf (F). weather station
Rommersheim (Rhineland-Palatinate - Germany) in 2009. Wheat cultivar with high Septoria
susceptibility (▬ simulation, • field data, + confidence interval of the field data)

leaf layer cultivar susceptibility

high mean low

under. corr. over. under. corr. over. under. corr. over.

F 6.3 81.3 12.5 6.3 75.0 18.8 6.3 62.5 31.3

F-1 31.3 68.8 0 12.5 81.3 6.3 6.3 68.8 25.0

F-2 50.0 50.0 0 31.3 68.8 0 12.5 68.8 18.8

F-3 75.0 25.0 0 62.5 37.5 0 43.8 50 6.3

Table 7. Validation of SEPTRI (n=60) - share (%) of underestimated, correct and
overestimated leaf blotch Epidemics on different leaf layers (2007 - 2009) (under.=
underestimation, corr. = correct, over.=overestimation)
According to the subjective validation, the model results are satisfactory. In most of the cases
(from 50 to 81.3%), excluding the leaf layer F-3, the disease severity progress was simulated
correctly (Tab. 7). For leaf layer F-3 a considerable share of underestimation occurred (from
43.8 to 75%). This means that epidemics on this leaf layer were poorly simulated. Otherwise
for use of the model in praxis the leaf layer F-3 has less importance because the action
threshold for the treatment scheduling is generally based on leaf layer F-2.