Novel fungicidal management for basal stem rot disease of coconut: In vitro and in vivo perspectives

Basal stem rot (BSR) disease, a lethal disease of coconut crop, induced by Ganoderma lucidum is prevalent and endemic in the East Coast region of the Tamil Nadu. The prolonged use of a single fungicide and the emerging issue of fungicide resistance raised concerns regarding disease control in this region. An integrated disease management strategy, incorporating new generation fungicides could help resolve these challenges. The Indian Council of Agricultural Research-AICRP on Plantation Crops (All India Co-ordinated Research Project) investigated different fungicides of single along with combination types against G. lucidum at three different concentrations (100, 250 and 500 ppm) in an in vitro study. Thirteen fungicides were screened and was found that hexaconazole 4 % + carbendazim 16 % SC, hexaconazole 5 % + validamycin 2.5 % SC as well as azoxystrobin 11 % + tebuconazole 18.3 % SC W/W were most effective in controlling G. lucidum even at lower concentrations. In field trial, two novel combination fungicides azoxystrobin 11 % + tebuconazole-18.3 % SC W/W and hexaconazole 5 % + validamycin 2 % SC, were utilized. In comparison to other treatments, treatment (T6), which consists of root feeding hexaconazole 5 % + validamycin-2.5 % SC @ 4 mL in 100 mL of water as well as drenching the soil with hexaconazole 5 % + validamycin-2.5 % SC @ 2 mL/L (15 L/palm) every three months, was the most successful in controlling the disease. This treatment reduced the BSR disease index by 12.43 % compared to the initial disease index and resulted in a 58.49 % increase in nut yield compared to the control.