Agriculture Reference
In-Depth Information
Blue mould
Penicillium italicum
Produces pale-green colony
on artificial media - pale
brown to yellowish or
orange brown on reverse
side - with a
characteristic sweet odour
Some isolates produce a
clear exudate on the
colony and a brown
soluble pigment in the
artificial media
Spores vary in size and
shape
Cylindrical to elliptical or
ovate conidia (2-3 ×
3-5
m
m) are produced in
long, disordered chains
Fruit
injuries
Infection almost identical to
green mould and sour rot,
with the exception of a
blue conidial mass that
form on decaying fruit
Diseased tissue becomes soft,
watery and slightly
discoloured
White powdery growth of
mycelium develops on
surface of lesion
Similar to green
mould
Blue mould grows
faster below 10°C
compared to green
mould therefore
more prevalent in
cold storage fruit
Prolific conidia
production ability
enables fungus to
develop resistant
strains against
chemical fungicide
treatments
Similar as for green
mould
Gutter 1975
Carlos 1982
Onions & Brady 1987
Whiteside
et al
. 1988
Eckert & Eaks 1989
Pitt 1991
Timmer
et al
. 2000
Sommer
et al
. 2002
Brown 2003b
FFTC 2003
Droby
et al
. 2007
Nunes
et al
. 2007
Syngenta 2007
Azizi
et al
. 2008
El-Mougy
et al
. 2008
Karimi & Rahemi
2008
Prado
et al
. 2008
Travallali
et al
. 2008
Sour rot
Geotrichum candidum
Grows rapidly on PDA,
producing a dull
gray-white colony with
chains of arthrospores
The mycelium is hyaline
and septate
Conidia can vary between
2-8 × 3-50
m
m and 3-6
× 6-12
m
m
Fruit
injuries
Initial symptom similar to
blue or green mould
Lesions first appear as water
soaked, light to dark
yellow slightly raised
spots
Cuticle is more easily
removed from epidermis
than in lesions formed by
blue and green mould
Cell degrading enzyme
produced by the fungus
causes the fruit to
disintegrate into a slimy
watery mass
Following exposure to high
RH the lesion may be
covered with a yeasty
sometimes wrinkled layer
of mycelium
Fungus occurs
commonly in soil
from where it is
dispersed to fruit
surfaces
Fungus invades the rind
through insect or
mechanical damage
Susceptibility of
infection increases
with fruit maturity
Amount of moisture
on the rind greatly
influences the
susceptibility of
fruit
Spore laden watery
debris from infected
fruits spread decay
to healthy fruits
Minimize injury to
fruits
Immediate storage of
packed fruit to
10 °C to delay
onset of the
disease
Proper hygiene at
packhouse
Pre-harvest fungicide
treatment with
guazatine gives
some measure of
control
Butler & Eckert 1962
Baudoin & Eckert
1982
Whiteside
et al
. 1988
Eckert & Eaks 1989
Sommer & Ewards
1992
Droby
et al
. 1998
Timmer
et al
. 2000
Brown 2003c
Plaza
et al.
2004b
Mercier & Smilanick
2005
Syngenta 2007
