Evaluation of Current Biological and Chemical Control Methods under Climate Change to Better Manage Stem Rot Disease in Groundnut

Background: Around 90% of global groundnut production takes place in semi-arid tropic (SAT) regions, highlighting its importance as a key oilseed and food crop that delivers essential nutrients for human consumption. However, climate change poses significant threats to both the yield and quality of groundnut products in these areas. Methods: During the rabi seasons of 2022-23 and 2023-24, potential Trichoderma and Bacillus isolates were collected from rhizospheric soils in Telangana at the Groundnut Pathology Laboratory, ICRISAT, Patancheru. These isolates were assessed for their antagonistic effectand effectiveness of fungicides against Sclerotium rolfsii at different carbon dioxide levels (400 ppm, 550 ppm and 700 ppm) in CO2 incubators. Result: Results showed that Trichoderma harzianum (T3) achieved 73.88% and 65.55% inhibition of the pathogen’s radial growth at 700 ppm and 550 ppm CO2 levels, respectively. Meanwhile, Trichoderma viride (T1) exhibited 62.10% inhibition at 400 ppm CO2. Bacillus tequilensis (B2) exhibited the strongest activity, reducing radial growth by 68.32% at 700 ppm. At 550 ppm, Bacillus velezensis (B4) achieved the highest radial growth inhibition, with a 65.55% reduction. At 400 ppm, Bacillus cereus (B5) demonstrated the greatest inhibition, reducing radial growth by 56.10%. Notably, 100% inhibition of Sclerotium rolfsii was recorded with both tebuconazole and thiram across all three CO2 levels. Azoxystrobin showed 93.05%, 86.38% and 80.55% inhibition at 700 ppm, 550 ppm and 400 ppm CO2 levels, respectively. Overall, the biocontrol activity of the fungal and bacterial bioagents increased with rising carbon dioxide levels, as did the effectiveness of the fungicides.