Vol. 11, Issue 2 (2022)

Author(s):
NS Punya, N Kiran Kumar, VB Sanath Kumar, SB Yogananda, KR Ashoka and HB Mahesh

Abstract:
By considering the major upcoming disease in rice growing areas, that is sheath blight in rice, caused by Rhizoctonia solani Kuhn and the huge chemicals used in rice production, including disease management, research was carried out at the College of Agriculture, V. C. Farm, Mandya, during Kharif 2020–21, in order to develop a new non-chemical strategy for managing the sheath blight disease in rice. A total of six bioagents were tested in vitro by using the dual culture technique, out of which Trichoderma harzianum showed the highest mycelial inhibition (60.37%), followed by Pseudomonas fluorescens (54.4%) and the least effective was T. asperullum (37.44%). Another in vitro study was done to test different plant extracts by using a poisoned food technique against R. solani at 1, 5, 10 and 20% concentrations. Seaweed extract (75.5%) and garlic extract (65.13%) were found to be the most effective in controlling pathogen growth. Then field experiment was carried out during Kharif 2020 with the most effective treatments of in vitro studies along with the biodegradable polymer chitosan and nano silicon. Out of all the treatments, most effective treatments with mean least mean disease severity were chitosan (12.50%) and nano silicon (14.79%) when compared to the chemical hexaconazole 5 EC (13.89%) which was used as a positive control and the least effective treatment was seaweed extract (20.41%), followed by T. viride (19.0%), whereas the untreated control showed 28.73% mean disease severity. In addition to the reduction in disease, these treatments also contribute to the growth and yield of the crop. Maximum grain yield and high Benefit cost ratio was recorded in the chitosan treatment (5350 kg/ha & 2.49) when compared to the hexaconazole (5157 kg/ha & 2.35), followed by nano silicon (4666.6 kg/ha & 2.31) and the least was seaweed @ 0.2% (4082.5 kg/ha & 2.08) followed by P. fluorescens (4015.83 kg/ha & 2.06) when compared to control (3125.0 kg/ha and 1.34).