Control of Botrytis cinerea strains resistant to iprodione in apple with rhodotorulic acid and yeasts

A Rhodotorula strain (Rhodotorula glutinis ySL 30) in combination with a siderophore was evaluated for postharvest control of a Botrytis cinerea strain resistant to iprodione on apple. The biocontrol yeast was less effective for the control of iprodione-resistant B. cinerea than the iprodione-sensitive B. cinerea. A combination of R. glutinis and rhodotorulic acid, a siderophore produced by yeasts belonging to Rhodotorula genus, was evaluated as a way to improve the control of the resistant strain. In experiments “in vitro”, rhodotorulic acid retarded the spore germination of the fungus, and in biocontrol experiments on apple wounds, the disease was more effectively controlled by the antagonistic agent in combination with the siderophore than by the antagonistic agent alone. R. glutinis reduced decay severity by 54% and R. glutinis in combination with siderophore reduced decay severity by 72%, in comparison with the non-treated control.