Leaf spot disease emerges on Kadamba trees

A team of plant pathologists-Dr Deewakar Baral, Dr Sukram Thapa and Dr Rodrick Lepcha from Lovely Professional University (LPU)-have reported a new leaf spot disease affecting Neolamarckia cadamba (kadamba) trees. This report highlights the emergence of a previously unknown pathogen.

The prevalence of this disease was first observed in December 2023, when necrotic leaf spot symptoms were noted on 20 per cent to 40 per cent of the foliage of kadamba trees within the LPU campus, as well as in fields of nearby villages in Punjab.

Kadamba trees are commonly grown along roadsides and are culturally and religiously significant. According to tradition, it was under the shade of this sweet-scented tree where Radha and Krishna are believed to have played in Vrindavan. Beyond its cultural importance, the tree is also known for its low-quality timber, paper and perfume production.

The disease identified by the pathologists is characterised by distinctive concentric ring spots surrounded by yellow halos on infected leaves. Affected samples were meticulously collected and fungal colonies appeared greyish. The conidial morphology of the fungus confirmed its association with the genus Alternaria.

To verify their findings, DNA analysis conclusively identified the pathogen as Alternaria ethzedia. The sequences of these isolates have been deposited in the NCBI GenBank, providing a global reference for further studies.

This report marks the first global documentation of A. ethzedia causing leaf spot disease on Neolamarckia cadamba. The kadamba tree, a culturally and ecologically important species, has not previously been reported to host this pathogen. The findings underscore the urgent need for further research into the management and mitigation of this emerging disease to prevent its spread and protect kadamba populations in the region.

The report from LPU’s team emphasises the importance of continuous plant health monitoring and collaborative efforts to combat emerging plant pathogens. It serves as a call to action for researchers, farmers and policymakers to focus on integrated disease management strategies for Neolamarckia cadamba.

Jalandhar