Biological control of strawberry crown rot is substrate dependent phenomenon

Abstract

BACKGROUND: Phytophthora cactorum crown rot is currently limiting strawberry cultivation worldwide. Arbuscular mycorrhizal fungi (AMF) and bacterial endophytes have shown promising results as biological control against the disease. Growing medium can also influence biological control and e.g., composts have been shown to suppress soil borne pathogens. OBJECTIVE: The aim of the study was to investigate the effect of AMF, endophytic bacteria and different growing media against strawberry crown rot. METHODS: Three pot experiments were conducted in greenhouse conditions. Each experiment tested different biological control methods with micropropagated strawberry 'Jonsok' inoculated or not with the fungus. The first experiment evaluated AMF strains on different growing media, the second experiment tested combinations of AMF and other biocontrol microbes. The third experiment tested the impacts of AMF, Pseudomonas fluorescens and compost. RESULTS: Biological control methods and disease inoculation had very different impacts on strawberries planted in different growing media. On suitable growing media, AMF increased growth and lowered disease symptoms, but P. fluorescens was not effective. The growing medium containing manure/wood fiber compost was the most disease suppressive. CONCLUSIONS: Biological control of strawberry crown rot with AMF is substrate dependent. Composts can be used to somewhat suppress crown rot.