Damage Assessment of bacterial leaf blight on rice crop utilizing remote sensing in Indonesia

The Government of Indonesia has launched agricultural insurance program since 2013. A key in agricultural insurance is damage assessment which is required to be as precise, quick, quantitative and inexpensive as possible. Conventional method is to inspect the damage by human eyes of specialist having experiences. This method, however, costs much and is difficult to estimate the infected field precisely in wide area. So there is increasing need to develop effective, simplified and low cost method using remote sensing and GIS, covering wide area. With this background, we conducted research on development of new method using remote sensing data for evaluation of damage ratio caused by bacterial leaf blight(BLB) in West Java, Indonesia.

During time between July 30 and August 2, 2017, damage assessment of BLB was conducted at first by damage assessors using current assessment method. Total number of paddy fields investigated was 22 and, in each field, 10 points were selected and assessed by damage assessors. Then, using Rapid Eye image obtained on July 17, reflectance value was extracted and a relation between each wave length range and the BLB damage assessment result by pest observer was evaluated. The result of the evaluation shows high positive correlation with reflectance of red and also RGI(Red-edge band x Green Band) of which values are 0.81 and 0.80 (significant at 1% level) respectively.

In addition, with use of Sentinel-2 data obtained on June 14, July 4 and July 19, 2017, we studied emergence time of BLB through evaluation of change in reflectance of satellite data. According to the results, there shows no change in the red reflectance and RGI about June 14 data which is about a month and half before harvesting time. However, July 4 data and July 19 data show that red reflectance and RGI value become higher as damage level gets higher. In case of paddy field where damage level is 60 80%, the red reflectance and RGI value increase more than 10 % in about 2 weeks.

Our results indicate possibility of developing new damage assessment method which could realize more effective BLB evaluation through integrating remote sensing into current method and utilizing the integrated data.

Key words, agricultural insurance, rice production, damage assessment of pest and disease , adaptation to climate change, food security, satellite data