A survey of land for Weligama coconut leaf wilt disease affected palms outside the declared boundary in the Southern Province.

Abstract

After the identification ofthe Weligama Coconut LeafWilt Disease (WCLWD) in 2006, a three km wide boundary zone was declared which stretched from Galle to Tangalle. All suspicious palms recorded within the boundary zone were removed. Gradual removal of affected palms in the core area was also continued. These actions along with many other precautionary steps were taken with the objective to prevent the spread ofthe disease further beyond the demarcated boundary. After taking continued precautionary measures for more than 7 years, it was timely to find out the presence of any disease affected palms beyond the boundary. Therefore, a sample survey was conducted along a 4 km wide belt beyond the boundary. Uniform sampling locations were ensured by selecting sample sites on a I km grid drawn on the areal image ofthe area. Each grid covered an area of I km2 (100 ha). Four sampling locations/plots ofapproximately I ha in extent were selected within each grid. All coconut palms within selected plots were examined for morphological symptoms ofthe WCLWD and necessary information was recorded. The total area covered by the sample survey was about 40,000 ha and the extent closely examined was about 1600 ha, which was approximately 4% ofthe total land area covered by the survey.