ASSOCIATION BETWEEN RICE CANOPY DENSITY BASED ON SENTINEL-2 NDVI AND PLANT PEST AND DISEASE OCCURRENCE IN PEMALANG REGENCY, CENTRAL JAVA

Abstract

Conventional plant pest and disease monitoring relies on labour-intensive field observations. To explore a more efficient method, this study was aimed to analyse the association between Sentinel-2 NDVI rice canopy density and the occurrence of four pests and diseases in Pemalang Regency. The study also tested whether any detected association is specific to one organism. District mean NDVI over the mapped paddy fields was related to pest-observation records from the 14 districts for the 2025/2026 wet season using the sign test. The results showed that from four pests and diseases analysed only bacterial leaf blight (Xanthomonas oryzae pv. oryzae) was significantly associated with canopy density while rice stem borer, rice bug and rice-field rat were not. Bacterial leaf blight occurrence rose from 9% in the sparsest canopy class to 59% in the densest. The canopy was also consistently denser in the months when blight occurred (sign test, P = 0,0020). Canopy density based on Sentinel-2 NDVI can therefore help prioritise the monitoring of bacterial leaf blight.