Comparison of AMF and PGPR inoculants for the suppression of Verticillium wilt of strawberry (Fragaria × ananassa cv. Selva)

Verticillium wilt, caused by Verticillium dahliae, is widespread in intensive strawberry (Fragaria × ananassa) growing areas. It is effectively controlled in site preparation by soil fumigation with methyl bromide but with the ban on ozone-depleting chemicals, which applies to methyl bromide, there has been an international effort to find alternatives, which will protect the crop from planting to fruit harvest and in runner production. These include chemical replacements and alternative disease control strategies. In this study, biological control, based on single and dual inoculation with a commercial arbuscular mycorrhizal inoculant containing Glomus spp. and a commercial plant growth promoting rhizobacterial inoculant containing a Bacillus sp., has been evaluated in the field. Control plants inoculated with V. dahliae had wilt symptoms, and marketable fruit yield was significantly reduced by approximately 60% whereas the yield of plants from runners inoculated with the AMF or PGPR inoculants did not differ significantly from that of the non-inoculated controls. Generally, marketable fruit size and plant and root fresh weight were not significantly different in the inoculated plants compared with the non-inoculated controls. There were no significant differences in the protection afforded by the AMF and PGPR inoculants and dual inoculation did not give greater protection than single inoculation.