Canadian goldenrod residues and extracts inhibit the growth of Streptomyces scabiei, the causal agent of potato common scab

Abstract

Common scab is one of the most important diseases affecting potato crops worldwide. Using fresh residues and/or bio-products of Canadian goldenrod (Solidago canadensis) may offer an alternative to harmful conventional fumigants. In this study, we aimed to: (i) conduct a preliminary investigation of the utilization of S. canadensis to reduce common scab severity (Experiment 1), and (ii) determine the allopathic potentials of S. canadensis extracts on Streptomyces scabiei (also known as S. scabies), the most important soil pathogen responsible for causing common scab in North America (Experiment 2). Compared with control plants, preliminary results showed that adding 1.2 kg of fresh S. canadensis residue per m2 reduced scab severity by about 45% (Experiment 1). Furthermore, hexane and dichloromethane extracts of S. canadensis, at a concentration of 200 µg·mL−1, inhibited the growth of S. scabiei by about 97% (Experiment 2). These results were comparable with those using tetracycline (2.5 µg·mL−1), a known inhibitor of S. scabiei. Both experiments suggested that S. canadensis may represent a new approach for controlling potato common scab. More studies are required to better understand the mechanisms involved in S. canadensis induced reduction of common scab in order to standardize the approaches.