The effect of rootstock selection, substrate composition and biological control agents in the management of the bell pepper pathogen Fusarium oxysporum f. sp. radicis-capsici

Abstract: Since 2021, wilting symptoms in bell pepper (Capsicum annuum L.) production were often associated with pathogenic Fusarium oxysporum f. sp. radicis-capsici (FORC). A
comparative inoculation trial was conducted focusing on rootstock selection. No symptoms
were observed, therefore substrate moisture contents were slightly increased in the second
half of the trial. In these conditions, growth inhibition and root discoloration indicated
vulnerability to FORC in ungrafted and self-grafted plants, as well as in a commercial
rootstocks. Three rootstocks did not show clear discrepancy between control and
inoculated plants, indicating a certain degree of tolerance and even resistance towards
FORC, as low qPCR signals were observed in the latter rootstock. A parallel trial studied
the use of organic substrate at three FORC inoculation levels. Results indicated that
substrate type did not alter disease progression. A dose-response effect was observed at
lower concentrations, with no additional effect at higher doses. A final trial was setup to
test the suppressive effect of biological agents towards FORC.