Pathogenic variability of Phytophthora spp. inciting Bud Rot of Coconut in Kerala

Author: Aswathi M.S. and Radhakrishnan N.V.

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Abstract

Bud rot caused by Phytophthora spp. is one of the most destructive diseases of coconut. The management of the disease is a major challenge due to the frequent development of pathogenic variability within the pathogens. It is necessary to comprehend the pathogenic heterogeneity among various pathogen isolates in order to design appropriate management strategies. Hence, the present study evaluated the variability in pathogenicity of thirteen different isolates of Phytophthora spp. isolated from coconut bud rot samples. Ten isolates from three different agroecological units of Kerala viz., AEU 8 (southern laterites), AEU 9 (south central laterites) and AEU 11 (northern laterites) and three from Central Plantation Crops Research Institute, Kasaragod were tested for their pathogenicity on detached spear leaves and nuts of West Coast Tall variety of coconut under in vitro. Two different methods viz., inoculation of mycelium as culture disc and zoospore suspension were employed and lesion size developed on nuts and leaves were recorded. The Phytophthora isolates recorded significant difference in the lesion size at regular intervals. The isolate 8A (P. palmivora) obtained from southern laterites was the most virulent one. The species P. palmivora and P. nicotianae were found to be almost similar in aggressiveness on coconut. The comparison of virulence between the isolates from different agroecological units indicated that, isolates from southern region of Kerala were found to be more pathogenic than northern region. The current investigation confirmed the presence of highly virulent Phytophthora spp. isolates in Kerala, which can pose an imminent risk to the coconut cultivation of the state.

Keywords

Phytophthora, pathogenicity, coconut, bud rot, variability

Conclusion

Hence, the present study suggest that isolates of Phytophthora spp. differ in their ability to cause the bud rot disease in coconut. Considerable pathogenic variability was observable among the isolates from same agroecological units of the state. Being the primary focus of breeding for resistance, the information on presence of pathogenic diversity within the species is significant. The highly heterogeneous nature of the isolates in their pathogenicity can pose a challenge in adopting the management practices and finally in the cultivation of coconut. Even though the isolates used in the study are less in number, the results with these isolates can be considered as a valuable basic information on the pathogenic variability among the Phytophthora isolates of Kerala.

References

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How to cite this article

Aswathi M.S. and Radhakrishnan N.V. (2023). Pathogenic variability of Phytophthora spp. inciting Bud Rot of Coconut in Kerala. Biological Forum – An International Journal, 15(10): 1129-1135.