PREVALENCE AND INCIDENCE OF BASAL STEM ROT DISEASE OF COCONUT IN SELECTED COASTAL REGIONS OF BANGLADESH AND ITS IN-VITRO MANAGEMENT

Abstract

Basal stem rot (BSR) caused by basidiomycotina fungi, Ganoderma is one of the most devastating diseases of numerous perennial, coniferous and palmaceous plants. In forest systems, Ganoderma has an ecological role in the breakdown or delignificat ion of woody plants. Symptoms of BSR disease can take several years to develop, and the presence of the pathogen (such as indicated by fruiting bodies) is often only visible when the fungus is well established and more than half of the bole tissue has been decayed, leaving no chance for the grower to cure the infected palms. A limiting factor in controlling the BSR disease is the lack of reliable diagnostic method(s) for early diagnosis. The present study was aimed to evaluate the occurrence and incidence of basal stem rot disease and identify its causal organism and to perform a bio-control based in-vitro management practices. The survey study was conducted in three selected coastal districts viz. Patuakhali, Barishal and Pirojpur during January 2018 to October 2019. The in-vitro management study was conducted in Molecular Biology and Plant Virology Laboratory under the Department of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka . The disease incidence of basal stem rot was measured 69.33%, 68.33%, 57% and the disease severity was 36.89%, 30.79%, 29.5% in Pirojpur, Patuakhali and Barishal respectively. The highest disease incidence (29.5%, 35.75% and 36.75%) was found in loamy soil, at 6 to 7 pH and in plant age group 36-40 years respectively. In total 45 root samples, 14 sporophore and 12 disease stem bits/barks were collected for aseptic isolation. Diseased root bits and sporocarp were good source(s) for isolation of Ganoderma with Potato Dextrose Agar and Potato Sucrose Agar that supported the highest radial growth and biomass production. The isolated pathogens from root samples were identified as Ganoderma applanatum and Ganoderma lucidum. The bio-control based management practices like Trichoderma suspension as bioagent,

Cattle urine as bio-product and Neem oil and Garlic extract as botanicals were applied for controlling the basal stem rot disease studied under in-vitro condition. Among the four bio-control agents cattle urine gave the best inhibitory actions against BSR disease under in-vitro condition which accounted lower radial mycelial growth at 9 DAI of Ganoderma (3 mm ) with 3 ml doses of application.