Competition between Colletotrichum species reduces anthracnose symptom development in Dioscorea alata yams: Potential for biopriming and breeding

Ecological interactions are a fairly overlooked component in agriculture, despite their known potential in productivity, pest and disease regulation. In this study, we assessed whether a potential low pathogenic congeneric competitor of Colletotrichum gloeosporioides could decrease disease onset in yams. We set up an experiment with artificial drop inoculation on detached leaves, with individual controls and treatments as either co-inoculation or inoculation with a harmless competitor 24 h prior to inoculating the pathogen. Our results demonstrate that direct admixing translated into accrued competition and disease symptoms, while prior inoculation of the competitor tended to decrease symptom development. There was variation in how varieties responded to treatments and in strain competitive ability altering the protective effect, but nevertheless these results suggest that incorporating such interactions in breeding programmes or working towards increased use of commensals in agriculture might confer improved disease control for crops.