Impact of spot blotch pathogen Bipolaris sorokiniana on important seed quality parameters in wheat and its management with biocontrol agents and newer fungicide molecules.

Abstract

Spot blotch disease is prominent amongst several biotic stresses challenging wheat yield and quality. The impact of seed inoculation with Bipolaris sorokiniana, on important wheat seed quality of popular cultivar (cv.) DBW 187, was estimated in comparison to susceptible check WH 147. DBW 187 responded very effectively against pathogen keeping all parameters well ahead of susceptible check. The variety could resist declination in per cent germination with 8.07% in comparison to WH 147 which resulted in 14.72% reduction in germination after pathogen inoculation. Similarly, after pathogen's inoculation, speed of germination (80.06) and vigour index I (2677) and II (24379) were significantly higher in cv. DBW 187 as against cv. WH 147, which resulted in lower speed of germination and vigour index I and II, i.e. 74.37, 2249, and 16715, respectively. Amongst the biocontrol agents, Trichoderma harzianum was found to be the most effective in managing this pathogen, which caused 86.30% inhibition in mycelial growth of B. sorokiniana. Amongst the seven fungicides used to manage Bipolaris sorokiniana in vitro, tebuconazole 50% + trifloxystrobin 25% WG, propiconazole 25% EC both at 75 and 100 ppm, and kresoxim methyl 44.3% SC at 100 ppm were most effective against Bipolaris sorokiniana, causing complete inhibition in its radial growth. Conclusively, wheat cv. DBW 187 has capacity to resist seed health deterioration caused by the pathogen. Out of seven evaluated fungicides, the best three newer fungicide molecules, viz., tebuconazole 50% + trifloxystrobin 25% WG, propiconazole 25% EC, and kresoxim methyl 44.3% SC, can judiciously be utilized in combination with biocontrol agents, Trichoderma harzianum, T. asperellum, and Chaetomium globosum, keeping the fungicide load minimum for the effective management of B. sorokiniana.