Report on outbreak and in vitro management of leaf spots disease caused by Pestalotiopsis sp. on oil palm seedlings in nurseries in Ghana

Abstract

Aims: Oil palm (Elaeis guineensis) is the most productive and the highest yielding edible oil crop in the world and economic crop cultivated in Ghana. In September 2017, an outbreak of leaf spot caused by Pestalotiopsis sp. on oil palm seedlings was reported for the first time in Ghana. The disease incidence reached 85%, assuming an epidemic situation. This study is geared towards developing appropriate management strategies by identifying phytopathogenic fungi that caused leaf spot on oil palm seedlings. Methodology and results: Ten symptomatic leaves were picked per plot into sterilized plastic Ziploc bags and brought to laboratory. The leaves were washed under running tap water, cut into 1 cm pieces each, surface-sterilized with 10% sodium hypochlorite solution, rinsed three times in sterile distilled water and blotted on tissue paper (Gonthier et al., 2001). The sterilized samples were transferred aseptically onto potato dextrose agar (PDA) plate containing 0.5 mg/L of chloramphenicol and subcultured till pure culture was obtained. The result showed pure white colony which was concentric, cottony and velvety with slimy black dots of conidia mass on the tip of aerial mycelia. The fungus isolated and identified from the lesions on the leaf was Pestalotiopsis sp. and its pathogenicity confirmed. Conclusion, significance and impact of study: The result from the study concludes that Pestalotiopsis sp. could infect E. guineensis, which developed the same symptoms observed naturally in the field after inoculation. The fungus was identified based on morphological characteristics.