Biocontrol strategy, Compost, Soil-borne pathogens management

The effect of different compost-soil ratios on the incidence of Pythium aphanidermatum causing tomato damping off was tested in a greenhouse experiment. The inoculum density of 5% was determined to be suitable for inoculation in compost experiments based on investigations of disease incidence with 5, 10 and 20% inoculum densities. To evaluate the effect of compost on incidence of tomato damping off, tomato seeds were sown in compost/soil mixtures at 10, 30 and 50% V:V containing 5% of P. aphanidermatum inoculum. The number of dead tomato seedlings was recorded in two-day intervals and disease incidence was calculated. Results showed that compost/soil mixtures at 30 and 50% ratios significantly suppressed Pythium damping off in tomato seedlings, while 10% compost/soil mixture had no significant effect on disease suppression. This suppression was biologically based since heat-sterilized compost offered little protection from the pathogen. There are antagonistic microorganisms in the composts which are potential biocontrol agents and can be used in bio-pesticides