Geostatistics of Oil Palm Trees Affected by Ganoderma Disease in Low and High Planting Density

Abstract This study was conducted to assess the influence of two oil palm planting density (PD) on the incidence and severity of the Ganoderma basal stem rot (BSR) disease in oil palm planted in a plantation at Bagan Datuk, Perak, Malaysia. Ground surveys were conducted in oil palm planted in two planting densities involved which are: 120 palms/ha (lowest PD) and 200 palms/ha (highest PD) to assess the incidence and severity of BSR disease in oil palm plantations, over the 25 years after planting, YAP. The presence of the BSR disease symptoms as visually assigned followed the Standard Operating Procedures (SOP) Guidelines for Managing Ganoderma Disease in Oil Palm. Semivariogram analysis was performed on the data to show the spatiotemporal structure of BSR disease at 10, 15, 20 and 25 years after planting. The disease incidence was observed in all both plots with 0.57% to 1.67% at 8 years after planting, followed by increased to 15.12% to 38.3% at 16 years after planting. At 25 years, high BSR disease incidence was recorded on 200 palms/ha (72.5%), whilst low BSR disease incidence was recorded on 120 palm/ha. Effects of nugget to sill were found relatively moderate to weak of spatial pattern distribution. The observed disease patterns suggest that the progress of BSR disease incidence is firstly randomly scattered (8 to 10 years after planting) and secondly by root-to-root contact of the disease spreading to neighbouring palms may be occurred. Further study is needed to investigate factors associated with the outbreak of BSR disease in these plantations.