Context-Dependent Effects of Seed Inoculation on Anthracnose Disease and Seed Yield of Bean ( ): Ambient Conditions Override Cultivar-Specific Differences.

Root colonizing fungi can stimulate plant immunity, but net effects are strain × cultivar-specific and changing ambient conditions further contribute to variable outcomes. Here, we used four spp. to inoculate seeds of four common bean () cultivars and explored in three different experimental setups the effects on fungal anthracnose after leaf inoculation with . Plants growing in pots with field soil under greenhouse conditions exhibited the highest and those in the open field the lowest overall levels of disease. Among 48 strain × bean cultivar × setup combinations, -inoculation enhanced disease in six and decreased disease in ten cases, but with the exception of B6-inoculated Negro San Luis beans, the strain × cultivar-specific effects on anthracnose severity differed among the setups, and anthracnose severity did not predict seed yield in the open field. In the case of Flor de Mayo beans, even reduced yield in anthracnose-free field plots, although this effect was counterbalanced in anthracnose-infected plots. We consider our work as a case study that calls for stronger emphasis on field experiments in the early phases of screenings of inoculants as plant biostimulants.