What is blue mold?
Blue mold, caused by fungus Penicillium expansum, is a common postharvest disease of apples and pears worldwide. Injuries to fruit, especially during picking and handling operations, are the primary points of entry of this fungus. At ordinary temperatures, infected fruit can rot in two weeks or less. Other names for the disease are soft rot, bin rot, and Penicillium rot.
What does blue mold look like?
- Soft, bluish-
green, light brown, furry coating of infected fruits begin around injuries or lenticels on the outer surface of fruit. - Rotted fruits have a characteristically moldy odor and flavor.
- Grayish blue masses of spores may appear on the fruit surface under high relative humidity conditions.
- Decayed tissue can be readily separated from the healthy tissue, leaving it like a “bowl”.
Where does blue mold come from?
- Survives in organic debris on the orchard floor, in the soil, and perhaps on dead bark on the trees.
- Conidial spores can also be present in the air and on the surface of fruit.
- Spores can survive for long periods under unfavorable conditions and can grow in temperatures as low as 32°F.
- Bulk bins, field crates, pack-house lines, and storage rooms are usually contaminated.
How do I prevent blue mold?
- Orchard sanitation to remove decayed fruit and organic debris on the orchard floor.
- Good harvest and handling management to minimize punctures and bruises on the fruit.
- Sanitizing dump-tank and flume water is essential to reduce infection.
- Picking bins and boxes can be disinfected with fungicides or steam.
- Disinfectants or fungicides can be used in fruit dips and combined with wax applications.
- Rapid cooling and storing of fruit under controlled atmosphere conditions.