Isolation and Characterization of Pathogen causing Black Leaf Spot in Rose

Author: Smilu Mohan M.S., R. Pramod and Archana Gilbert

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Abstract

Black leaf spot, a common disease found in roses, is a major threat to rose production in India. Diplocarpon rosae is believed to be the major pathogen associated with this disease. There have been some controversial reports regarding its etiology. In a study conducted in the Department of Plant Pathology, College of Agriculture, Vellayani revealed that the causal organism responsible for black spot of rose in the southern part of Kerala state, i.e., Thiruvananthapuram and Quilon district, was Colletotrichum gleosporioides. The present study focused on the isolation, cultural, morphological, and molecular characterization of the causal organism. Diseased samples were collected, isolated and Koch’s postulates were proved. Morphological and molecular characterization of the pathogen was done. The results confirmed the presence of Colletotrichum gleosporioides, showing 99.7% similarity

Keywords

Rose, Colletotrichum gleosporioides, black leaf spot, morphology, molecular

Conclusion

In this study, rose leaves affected by black leaf spot were harvested from plants exhibiting the most severe disease symptoms. Subsequently, a standardized isolation protocol was employed, leading to the growth of Colletotrichum gloeosporioides after an incubation period of 5 to 7 days. Koch’s postulates were confirmed, and both cultural, morphological, and molecular characterizations of the pathogen were conducted, yielding results that corroborate the presence of Colletotrichum gloeosporioides. Some results from the previous studies on the causal organism of black spot were found to be Diplocarpon rosae (Gachomo et al., 2006) which was different from the present study. Li et al. (2023) found the pathogenic fungi of rose black spot was Alternaria sp. on PDA plates, and they also reported the presence of new fungi, Gnomoniopsis rosae, which belongs to the phylum Ascomycota, order Diaporthales, family Gnomoniaceae, and genus Gnomoniopsis, for the black spot of rose. In another study done by Mohd Asmadi et al. (2020), four fungal isolates have been successfully isolated from rose black leaf spot namely, Rhizoctonia sp. (one isolate), Colletotrichum sp. (two isolates) and Penicillium sp. (one isolate). So, it is crucial to accurately identify fungal infections in order to plan an effective strategy for managing the black spot disease in rose production

References

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How to cite this article

Smilu Mohan M.S., R. Pramod and Archana Gilbert (2024). Isolation and Characterization of Pathogen causing Black Leaf Spot in Rose. Biological Forum – An International Journal, 16(10): 61-66