Agriculture Reference
In-Depth Information
that are spherical and
have tapered beaks
(200-800 μm long). The
ascospores are hyaline,
two celled and contains
two guttulae
Alternaria rot
Alternaria citri
- Black rot
On PDA, the mycelia
produced are yellowish
or olivaceous hyaline
Conidia are short-clavate,
oblong and dark olive
brown (15-22 ×
25-40 μm) and have four
to six septa
Alternaria alternata
-
Brown spot
Characteristic of the genus
is dark-colored multi-
celled conidia formed in
chains Conidiophores
septate and brown
Flower,
young
fruit,
navel
Fruit have a blackish
discoloration at the
blossom end. Internal
tissue dark with
unpleasant taste. An
important disease for juice
production
Brown to black dots to pock
marks on fruit, leaves and
twigs surrounded by a
yellow halo
A host-specific toxin is
produced that causes
necrosis
Airborne conidia form
a quiescent
infection in styler
end and forms
infection when
button becomes
senescent
Spores are produced
10 days after
infection.
Favourable
temperatures
combined with
8-10 h of wetting
period is required
for infection
Preventing stress on
fruit limits black
rot
Remove infected fruit
and delay harvest
until infected fruit
have dropped
No pre-harvest
applications
Disease free nursery
trees
Fungicide sprays with
the aid of
weather-based
model
Eckert & Eaks 1989
Olsen
et al
. 2000
Timmer
et al
. 2000
Atsunorl
et al
. 2001
Cals 2005; 2007
Reqaeian &
Aboutalebi 2007
Adaskaveg
et al
.
2008
Dewdney & Timmer
2009a; 2009b
Phytopathology 2009
Anthracnose
Colletotrichum
gloeosporioides
The fungal colony vary from
white to gray or black
Acervuli are erumpent and
superficial and
90-270μm in diameter
Conidia are oval or oblong,
(10-16 × 5-7 μm)
Ascospores are hyaline,
slightly curved and
nonseptate (3.5-5 ×
12-22 μm)
Fruit
Symptoms normally appear
on fruit that are injured:
Brown or black spots appear
on fruit
Decay may be dry and firm
and as the decay
progresses the rind
becomes grayish and
eventually a soft rot
occurs
Conidia are produced
on dead twigs and
spread through
water
Ascospores germinate
on fruit surface but
remain dormant
until fruit tissue is
weakend by other
factors
Ethylene treatment
triggers fungal
growth and
increases the
susceptibility of
further rind invasion
Careful handling of
fruits to avoid
injury
Reducing amount of
dead wood
available for
inoculum
production
Pre- and postharvest
fungicide
applications
Echert & Brown
1986
Eckert & Eaks 1989
Timmer
et al
. 2000
Barkley 2003
Ritenour
et al
. 2003
Taverner 2003
USAID 2004
Zhang & Timmer
2007
Infonet 2009
surface
