Forewarning Rice Blast in India

Forewarning Rice Blast in India
VI. APPLICATION OF THE FOREWARNING MODEL OF DRR
The best-fit equation developed for blast severity was used for forecasting the
disease based on the preceding week weather variables and blast severity. The
threshold level of predicted disease considered for spraying of fungicides was around
10 %. Observations on leaf and neck blast were taken at regular intervals and
predictions were made for each observation (Table 14 and 15). Based on the prediction
of the disease severity, timely spray of the fungicides was suggested to control the
disease (Table 16). Forewarning plots are compared with the plots with no forecast
situation (untreated plots).
Table 14. Observed and predicted leaf blast severity in treated plots of different sowings
Date of
1
observation
st Sowing: 21/6/2004 2nd Sowing: 06/7/2004 3rd Sowing: 20/7/2004
Observed Predicted Observed Predicted Observed Predicted
23.8.04 1.3 1.9 0.5 1.2 0.0 0.0
28.8.04 3.6 5.8 2.0 4.4 0.0 0.0
31.8.04 5.2 9.7 3.6 8.2 0.0 0.0
03.9.04 9.4 13.7 5.0 9.8 1.4 6.5
07.9.04 8.8 13.7 10.1 14.9 4.4 9.8
10.9.04 8.2 13.1 9.5 14.2 11.5 16.0
13.9.04 8.0 10.9 9.1 11.9 10.9 13.5
16.9.04 7.8 12.2 8.8 13.1 10.6 14.7
20.9.04 7.1 14.8 8.6 16.2 10.2 17.6
23.9.04 6.6 13.8 8.0 15.1 9.5 16.4
27.9.04 6.2 13.1 7.7 14.4 9.1 15.7
30.9.04 6.0 12.8 7.4 14.0 8.8 15.3
04.10.04 5.8 14.9 7.1 16.1 8.0 16.9
07.10.04 5.0 13.6 6.5 15.0 7.5 15.9
11.10.04 4.7 9.2 5.8 10.2 7.0 11.3
14.10.04 4.5 10.3 5.4 11.2 6.5 12.2
18.10.04 4.2 12.4 5.1 13.2 6.1 14.1
21.10.04 3.9 13.7 4.8 14.5 5.6 15.2
25.10.04 3.3 12.4 3.9 13.0 5.1 14.0
28.10.04 2.5 9.5 3.0 9.9 4.5 11.2
Table 15. Observed and predicted neck blast incidence in treated plots of different sowings
Date of
1
observation
st Sowing: 21/6/2004 2nd Sowing: 06/7/2004 3rd Sowing: 20/7/2004
Observed Predicted Observed Predicted Observed Predicted
32
14.10.04 0.1 1.7 0.2 1.8 0.0 0.0
18.10.04 0.2 4.6 0.5 4.9 0.3 4.7
21.10.04 0.4 7.4 0.8 7.8 1.1 8.0
25.10.04 0.8 4.9 1.4 5.4 2.3 6.1
28.10.04 1.3 2.1 2.0 2.7 3.6 3.9
1.11.04 1.6 0.8 3.3 2.2 5.3 3.7
4.11.04 2.2 0.1 4.0 1.3 5.9 2.9