A report of collar rot disease of Sugandh mantri (Homalomena aromatica) caused by Sclerotium delphinii in West Tripura state of India
Introduction
Homalomena aromatica Schott. (Araceae) is commonly known as Scented Arum or Sugandh mantri in Hindi. It is an aromatic perennial rhizomatous shrub (0.5–0.8 m in height) found in sub-tropical humid climates of Central America and Asia. The rhizome of Sugandh mantri contains essential oil commercially known as montria oil, which is used in perfumery and cosmetic industries (Sahu and Sahu 2015). The plant is being widely used as a traditional medicine in Indian Ayurveda (Kehie et al., 2017). Still, no fungal, bacterial and viral diseases have been reported in India and world on this crop. But, during the field survey in 2018–19, collar rot was observed on plant stem of Sugandh mantri in a field in Agartala district of West Tripura state (Fig. 1). The objective of the present study was to identify the causal organism of the disease through cultural, morphological and molecular methods and conduct the pathogenicity tests to confirm the causal organism.
Section snippets
Sampling and pathogen isolation
A field survey was conducted during 2018–2019 in Agartala district in fields (23°54′48.9″N 91°19′13.4″E), in West Tripura state and ten diseased plant samples were collected for further studies. The samples were washed in tap water to remove surface impurities and then dried on sterile blotting paper. The affected plant parts were separated and surface sterilized with 0.25% sodium hypochlorite solution (NaOCl2) for 1 min, washed thrice with sterile distilled water and then placed in Petri
Disease incidence and pathogen identification
During the study, six fields were surveyed and 25 plants of Sugandh mantri out of 120 were found to be infected with collar rot (20% disease incidence). The collar rot symptoms initially appeared on leaves as they began to turn yellow and dark brown necrotic lesions appeared on the stem base (Fig. 1.). Later, the affected plant exhibited visible collar rot symptoms and death of the plant. The fungus was consistently isolated from stem tissues of symptomatic Sugandh mantri plants. The surface of
Discussion
Sugandh mantri is an aromatic herb usually found in sub-tropical humid climates of Central America and Asia. It has good phytochemical properties hence widely used as traditional medicine in Indian Ayurveda to treat various wounds, diarrhoea, fever, cough, stomach disorders and certain types of central nervous system disorders (Kehie et al., 2017). No pests and diseases have been reported in India and elsewhere on this crop so far. But, in current investigation collar rot disease symptoms have
Conclusion
In the conclusion, Sugandh mantri plant found infected with collar rot disease and symptoms showed as dark brown necrotic lesions on the stem base. The incidence of disease was recorded 20% and the pathogen identified S. delphinii. This causal agent was first identified based on morphological characteristics and then confirmed by molecular methods using phylogenetic analysis. Finally, with the help of Koch's postulate S. delphinii was confirmed as causal agent. Based on current investigation
CRediT authorship contribution statement
Deeba Kamil: Supervision, Conceptualization, data curation. Amar Bahadur: Investigation, Methodology. Prasenjit Debnath: Experimentation. Shiv Pratap Choudhary: Draft and review manuscript. Anjali Kumari: Experimentation. Amrita Das: Manuscript review and editing.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
The authors are thankful to the Head, Division of Plant Pathology, ICAR-IARI for providing laboratory facilities and valuable guidance to carry out the present work.
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