CONTROLLING STEM CANKER AND BLACK SCURF DISEASE COMPLEX ON POTATO PLANTS USING TRICHODERMA ISOLATES

Abstract

Rhizoctonia solani, the causal agent of stem canker and black scurf disease on potato is a real threat to potato crop with up to 50% yield reduction. Current study was carried out to determine the effect of some Trichoderma isolates with different types of soil on the above diseases under laboratory and glasshouse conditions. Eight non-pathogenic strains of Trichoderma were isolated from potato roots and surrounding soil and examined for antagonism of Rhizoctonia diseases. Results showed that strains T. hamatum T8 and T. harzianum T5 had great potential as biocontrol agents for inhibiting the pathogen growth in dual culture and culture filtrate methods. The effect of different types of soils on the radial growth of R. solani AG-3PT in plates showed that Dorrigo soil inhibited the pathogen growth in laboratory by 68% as the colony diameter of pathogen recorded 2.8 cm which exceeds other soil types. While most Trichoderma strains that isolated from this area had a potential of protecting potatoes from the infection by the pathogen and acted as a biocontrol agent. Applying non-pathogenic Trichoderma isolates was the best method when inoculated the soil of pots with conidial suspensions which promote the growth of potato plants. T. harzianum (T5), T. hamatum (T6) and T. hamatum (T8) strains were eliminated stem canker and black scurf disease and improved potato plant growth in glasshouse experiment. The outcome of current study indicated the potential for utilizing Australian Trichoderma strains to reduce Rhizoctonia diseases on potato plants and increase productivity.