Journal of Advances in Biology & Biotechnology

Stevia (Stevia rebaudiana Bertoni) has become a valuable crop due to its natural sweetness and wide-ranging applications in both the food and pharmaceutical industries. Despite its potential, stevia cultivation is hindered by diseases like aerial blight, caused by the fungal pathogen Rhizoctonia solani Kuhn, which leads to significant yield losses. This study explores the potential of Bacillus subtilis, a biological control agent, in mitigating the effects of this disease. Conducted during the kharif season of 2023-24, the experiment assessed various dosages (1- 4 l/ha) of the bioagent (Bacillus subtilis) and their effects on plant health, disease resistance, and overall yield. The results indicate that the application of Bacillus subtilis not only reduced the severity of aerial blight but also enhanced key growth parameters, including plant height and sucker production. During evaluation, all the seven treatments were found to be significantly superior over control in managing the disease. Among all the treatments the growth parameters were maximum in T₅   ( Bacillus subtilis @ 3 l/ha) such as plant height (56.83 cm) number of suckers (55), fresh leaves yield (4.51) and dry leaves yield (4.00) and minimize the disease intensiy @ 12.23 % followed by T₄ (Bacillus subtilis @ 2.5 l/ha),  T₆ ( Bacillus subtilis @ 3.5 l/ha) ,T₇  (Bacillus subtilis @ 4 l/ha) ,T₃  (Bacillus subtilis @ 2 l/ha) ,T₂ (Bacillus subtilis @ 1.5 l/ha),T₁ (Bacillus subtilis @ 1 l/ha) and T0 (untreated). Furthermore, an economic analysis confirmed the cost-effectiveness of this biological treatment, highlighting its potential as a sustainable alternative to chemical fungicides in stevia farming.