Integration between chitosan and Zataria multiflora or Cinnamomum zeylanicum essential oil for controlling Phytophthora drechsleri, the causal agent of cucumber fruit rot

•Control of Phytophthora drechsleri by chitosan (CS) and ZEO or CEO essential oils was tested.•Fungal growth was reduced by increasing the concentrations of CS, ZEO and CEO.•In vivo assays showed the ability of CS and ZEO/CEO to control Phytophthora drechsleri.•Control of postharvest gray mold of cucumbers achieved by combined treatments.

This study reports the efficacy of chitosan (CS) in combination with Zataria multiflora (ZEO) or Cinnamomum seylanicum (CEO) essential oil to inhibit Phytophthora drechsleri in vitro and on artificially infected cucumbers for a storage period of 10 days. The fungal growth significantly was reduced by increasing concentrations of ZEO, CEO and CS that CEO was the most effective. Moreover, combined treatments showed more significant mycelial inhibition results and reduction of the IC50, MIC and MFC values compared with pure EOs or CS (p < 0.05). The most effective treatments in reducing mycelial growth were those based on the combination of CS with CEO (CC) or ZEO (CZ). In fruit decay assays, the combined treatments (CC and CZ) were able to reduce fungal decay in the range of 77-85% at day 9, compared with in the control.