Pilot testing of two biofungicide formulations for the control of citrus blue and green mold in two Moroccan packinghouses

Pichia guilliermondii strain Z1 and Bacillus subtilis strain ZH2 were previously selected for their high and reliable antagonistic activities against Penicillium digitatum (Sacc.) and blue mould (P. italicum Weh.) on citrus fruits. The effectiveness of pilot testing of wettable and a granular powder formulation based on each biocontrol agent was evaluated and compared to thiabendazole in two packinghouses. Each fruit was wounded on the outer surface on two opposite locations. Fruits intended to be treated with biofungicides were recovered just before applying the wax at packaging line. Fruits were soaked in a solution made with each formulation. Pathogenic inoculation was made 24 hours later by spraying two different varieties of fruits, Clementine ‘Nules’ and ‘Valencia-late’ orange, with a suspension of 105 conidia/ml of P. italicum or P. digitatum. The effect of treatment was evaluated after 7 days of fruit incubation at two temperatures 4 °C and 20 °C. The result showed that the control achieved with strain Z1 on ‘Valencia late’ orange was comparable to that with thiabendazole. On the other hand, the decay control was lower for all the treatments on the Clementine ‘Nules’. Nevertheless, ZH2 strain has no effect at 4 °C. Therefore, it was concluded that strain Z1 is a promising biocontrol agent for the control of major postharvest diseases of citrus in Moroccan packinghouse stations. Keywords: Citrus, biological control, formulation, packinghouse, Pichia guilliermondii, Bacillus subtilis