Effect of plant defense inducers on mycelial growth of Sclerotinia sclerotiorum causing stem rot of Indian mustard

Abstract

 Plant defense inducers are emerging compounds for disease management that can induce systemic resistance response in 
host plants at lower concentrations. Thus, the present study was undertaken to study the effect of plant defense inducers 
namely salicylic acid (SA) and sodium propionate (SP) on growth and development of Sclerotinia sclerotiorum which 
causes stem rot of Indian mustard. SA and SP along with carbendazim 50WP and azoxystrobin 23SC were tested against 
S. sclerotiorum using poisoned food technique at the concentration of 50, 100 and 150 ppm. The results showed that 
plant defense inducers with increased concentrations not only affected mycelial growth but also the formation of 
sclerotia, its weight and size significantly (p=0.05). Carbendazim 50WP at all tested concentrations was the most 
effective in completely inhibiting mycelial growth followed by SA @ 150 ppm (49.44%), and SA @ 100 ppm (30.59%). 
Although SP and azoxystrobin did not result in mycelial growth inhibition, they showed reduction in sclerotia count with 
increased concentrations. The lowest sclerotia count was observed for SA @ 150 ppm (12) while SP @ 50 ppm (54) 
showed the highest count. Inhibitory effect of chemicals on sclerotial growth subsequently reflected in reduction in 
weight and volume of sclerotia. Our findings show that SA and SP as plant defense inducers at tested concentrations 
possess lower antimicrobial activity as compared to fungicides and thus can be further utilized for disease management 
of stem rot of Indian mustard.