Geospatial Mapping of Cephaleuros sp. Distribution: A QGIS-Based Assessment of Parasitic Green Algae’s Impact on Agricultural Crops in Selected Municipalities in Oriental Mindoro

This study investigated the spatial distribution and agricultural impact of Cephaleuros species, commonly known as parasitic green algae causing algal leaf spot on crops, in four selected municipalities of Oriental Mindoro namely: Naujan, Victoria, Bongabong, and Mansalay. With limited existing research on Cephaleuros in the province and its potential threat to crop productivity, a mixed-method approach was employed, incorporating field surveys, farmer interviews, and Geographic Information System (GIS) mapping using QGIS. Disease symptoms, impacts and management practices were further analyzed through descriptive statistics and correlation analysis. Results revealed that Cephaleuros sp. infects a diverse range of fruit-bearing crops however, banana varieties appeared not affected or non-hosts. Spatial analysis confirmed that disease occurrence was widespread across the four municipalities, suggesting environmental adaptability of the pathogen and clustered patterns. Quantitative correlation analysis showed that disease symptoms were highly and significantly correlated with changes in crop growth (r = 0.489, p < 0.001), impact on income (r = 0.485, p < 0.001), and percent income loss (r = 0.371, p < 0.001). Income losses among farmers reached up to 100% in severely affected areas, primarily due to reduced fruit yield and quality and increased management costs. Management strategies such as pruning, fertilizer and pesticide applications, and smoke cleansing were commonly practiced but predominantly (80–93%) found ineffective. Moreover, results showed low correlations between management interventions and income recovery, indicating the need for more effective, site-specific disease control strategies. In general, findings highlight the wide host range and economic threat posed by Cephaleuros sp. infection in Oriental Mindoro. Thus, results emphasize the necessity of continuous disease monitoring, development of standardized management protocols and farmer education to minimize yield loss and safeguard agricultural productivity in the region.