Penicillium Expansum

Kingdom:FungiPhylum:AscomycotaClass:EurotiomycetesSubclass:EurotiomycetidaeOrder:EurotialesFamily:TrichocomaceaeGenus:PenicilliumSpecies:P. expansum

Comparison between blue mold and Mucor rot 

Characteristics Blue mold Mucor rot

Texture soft, watery very soft, juicy

Color of decayed area

light tan to dark brown

light brown to brown

Signs of pathogenwhite mycelium, blue or blue-green spore masses

gray mycelium with dark sporangia

Color of internal flesh brown light brown to

brown

Odor earthy, musty sweet

Disease Cycle

• Penicillium expansum infects a fruit only when there are wounds that the conidia are able to enter. Usually, puncturing, bruising and limb rubs occur during harvesting, packaging, and processing of the fruit all of which are sites the spores can enter the fruit. Conidia can be found throughout the soil, decaying debris, tree bark and because the fungi is pyscophylic it is able to survive cold termperatures.

• the conidia may be isolated from the air of the orchard and packaging house, on the walls of the packaging houses, and as well as from the water and fungicide solution that the apples and fruits are dunked in before processing and packaging.

• Since the conidia exists and survives in every step and environment of the growth, harvesting, processing, shipping, and storage processes the wounded or damaged fruit may be inoculated at any one or more of these phases.

• After the conidia have access into the fruit or the stem, the conidia germinate and form a germ tube. This germ tube will continue to grow into hyphae and eventually mycelia to colonize the area. Successful growth of the fungus is reliant on the conditions of the environment.

Symptoms:

Blue mold is a common postharvest disease on apples and pears worldwide. This disease is an economic concern not only to the fresh-fruit industry but also to the fruit-processing industry because some strains of Penicillium expansum produce the mycotoxin patulin, which can rise to unacceptable levels and thus affect the quality of apple juice.

Symptoms:• The appearance of the decay caused by

most species of Penicillium is very similar.

• The rotted areas are soft, watery and light brown in color. The surface of older lesions may be covered by bluish-green spores that initially are nearly snow white in color.

• The lesions are of varying shades of brown, being lighter on the yellow or green varieties and on the pale cheeks of colored varieties and showing dark shades of brown on the most highly colored varieties.

Symptoms:

• Blue mold originates primarily from infection of wounds such as punctures, bruises and limb rubs on the fruit. Blue mold can also originate from infection at the stem of fruit.

• Blue or blue-green spore masses may appear on the decayed area, starting at the infection site. Decayed fruit has an earthy, musty odor. The presence of blue-green spore masses at the decayed area and associated musty odor are the positive diagnostic indication of blue mold.

Symptoms and signs of blue mold caused by Penicillium expansum on apples and pears.

A: Decayed area brown, soft and watery, with sharp margin; mostly originating from infection of wounds; blue-green spore masses

B: Decayed tissue completely separable from the healthy tissue, leaving it like a "bowl"

C: Blue mold originating from infection of wound on a Granny Smith fruit; spore masses formed at the infection site

D: Blue mold originating from infection at the stem or stem-bowl area of a Red Delicious fruit

F: White mycelium and blue spore masses at the decayed area of a d'Anjou fruit