Abstract:

In order to reduce the dosage of fungicides and find an effective control method for postharvest diseases of citrus,
the effect of Pichia membranefaciens in combination with low-dose fungicides (carbendazim and thiophanate-methyl) on
the control of postharvest citrus diseases was studied. Fungicides which could be well combined with P. membranaefaciens
were selected and the sensitivity of common citrus pathogens to the selected fungicides was verified. The postharvest fruits
were then used to validate the controlling effect of P. membranefaciens combined with fungicides on their diseases. The in
vitro experiments showed that neither carbendazim nor thiophanate-methyl inhibited the growth of P. membranaefaciens.
However, Penicillium italicum, Penicillium digitatum and Colletotrichum gloeosporioides showed different sensitivities
to the two fungicides, but the EC50 values were all lower than 1% of the recommended dosage. The in vivo experiments
showed that the treatment with P. membranefaciens in combination with either carbendazim or thiophanate-methyl had a
better control efficacy on blue mold and green mold than the individual treatments. However, the anthracnose rot in Valencia
orange was not well controlled by Pichia membranefaciens combined with thiophanate-methyl. The combined treatments
had a synergistic control effect on the incidence of Valencia orange diseases and an additive effect on that of Jincheng, which
could be an effective strategy to maintain good commercial rates of Valencia orange and Jincheng.

Key words: Pichia membranaefaciens, fungicide, citrus fruit, postharvest diseases