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Blue Mold Gallery

ID Gallery: Blue Mold

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exterior view of five apples in various stages of decay - image rotates to bring each apple into the foreground

View the 360 Rotator
showing multiple images of the external disease symptoms.

the interiors of five apples in various stages of decay - image rotates to bring each apple into the foreground

View the 360 Rotator
showing multiple images of the internal disease symptoms.

Blue Mold on Apples

Blue mold (primarily Penicillium expansum) is a very common postharvest fungal disease on apples worldwide. This disease is of economic concern  to both the fresh-fruit industry and the fruit-processing industry because some strains produce the mycotoxin patulin, which can rise to unacceptable levels affecting the quality of apple juice.

For full description of Blue mold and management visit our Blue Mold Postharvest Disease page.

Click on images below to see full size.

Red Delicious apple with blue mold side infection showing blue-green spore masses.

Blue mold originating from infection of wound on fruit; decayed area brown, soft and watery, with a sharp margin; blue-green spore masses visible. Photo: CL Xiao, USDA-ARS.

Internal view of a red delicious apple with a brown core area

Blue mold decayed tissue completely separable from the healthy tissue. Photo: CL Xiao, USDA-ARS.

Granny Smith apple with a side wound infected with Blue mold showing spore masses.

Blue mold originating from infection of wound on a Granny Smith fruit; spore masses formed at the infection site. Photo: CL Xiao, USDA-ARS.

Fuji apple infected at the calyx end with blue mold, often associated with drenching.

Calyx-end blue mold on a Fuji fruit; usually associated with drenched fruit. Photo: CL Xiao, USDA-ARS.

an apple with a large brown, soft spot with gray-blue and white flecks

Blue mold on Fuji apple. Brown, soft and watery lesion with sharp margin. Originating from a wound. Notice white & green spore masses. Photo: A. Amir, WSU Plant Pathology.

a green apple with a large brown area with blue-gray flecks

Blue mold originating from wound infection on Granny Smith apple. Spore masses formed along the infection site. Photo: CL Xiao. USDA-ARS.

interior of an apple - about half is brown

Cross section of blue mold lesion on Granny Smith apple. Sharp margin between decayed and healthy tissue. Photo: A. Amiri, WSU Plant Pathology.

a red apple with a large area missing and brown inside

Decayed tissue completely separated from the healthy tissue, leaving a “bowl-like” cavity. Photo: CL Xiao, USDA-ARS.

entire apple is brown with a lot of blue-gray flecks

Advanced blue mold. Conidia are very light and easily dispersed to neighboring fruit with the slightest movement. Photo: A. Amiri, WSU Plant Pathology.

red apple, about half brown with a few gray and white small mold spots

Honeycrisp apple showing the brown, soft, watery lesion with a definitive edge. Photo: TJ Mullinex, Good Fruit Grower.

An apple with the rotten portion removed, leaving about 2/3 of it

Internal view of a Honeycrisp apple with blue mold infection. The decayed tissue was easily separated from the remaining healthy tissue. Photo: TJ Mullinex, Good Fruit Grower.

a red-yellow apple with with a large area removed

View looking straight into a Honeycrisp apple with blue mold infection originating from a side puncture. The decayed tissues was easily separable from the healthy flesh. Photo: TJ Mullinex, Good Fruit Grower.

Blue Mold on Pear

Click on images below to see full size.

a pear with a large brown area with blue and white spots

Blue mold on a Bosc fruit; watery decay lesion with white mycelium and blue spore masses. Photo: CL Xiao, USDA-ARS.

the top part of a pear with blue and white mold on the top and base of the stem

Stem-end blue mold on a Bosc pear fruit after an extended period of storage. Photo: CL Xiao, USDA-ARS.

a green pear with a large brown area with white flecks and a patch of blue-gray

White mycelium and blue spore masses at the decayed area of a d’Anjou fruit. Photo: CL Xiao, USDA-ARS.

large brown spot on a pear with blue-gray and white in the center

Stem-end blue mold commonly seen on d’Anjou pears, particularly after an extended period of storage. Photo: CL Xiao, USDA-ARS.