Incidence, Symptomology, Morpho-molecular Characterization of Agroathelia rolfsii (Sclerotium rolfsii Sacc.): The Causal Agent of Basal Rot in Chabaud Carnation

Basal rot or sclerotium rot is one of the most serious and deadly disease in wide range of crops, including carnations. In carnations, it causes significant damage and economic loss.

The Agroathelia rolfsii, basionym: Sclerotium rolfsii Sacc., the causal agent of basal rot in Chabaud carnation was ioslated from diseased plant parts collected from the Horticultural Research Farm, Assam Agricultural University, Jorhat, in 2023–2024 consequently, the study on the disease incidence (%), symptoms and morphomolecular characterization of the pathogen was carried out.

The incidence of basal rot was recorded the maximum in April (25.78%). The symptoms first appeared in the basal region, just above the ground, which gradually progressed upward over time. Colonizing white mycelia were conspicuous, producing white smooth fruiting bodies that turned brown, resembling mustard seed grains. The disease caused constriction at the infected point, resulting in decaying of the tissue and collapse of the plant eventually. The culture exhibited compact, whitish, cottony mycelia with sclerotia grown over time. Additionally, the DNA sequence of fungal isolate was submitted to NCBI, with an accession No. PP 203038. The fungal isolate had 92.99% similarity with A. rolfsii and a phylogenetic tree was constructed according to its nearest species with a bootstrap value.