Agriculture Reference
In-Depth Information
Table 4.4
Continued
Infection
site
Disease cycle and
epidemiology
Disease
Description of casual agent
Fruit symptoms
Control
References
Black spot
Guignardia citricarpa
Ascocarps are aggregated
and globose
(100-175 μm)
Asci are clavate cylindrical
and eight-spored.
Ascospores are aseptate,
hyaline, multiguttulate,
cylindrical and swollen
in the middle (4.5-6.5 ×
12.5-16 μm)
Conidia are obovate to
elliptical, elliptical,
hyaline, aseptate and
multiguttulate with a
colourless subulate
appendix (5.5-7 ×
8-10.5 μm)
Most
critical
at fruit
set
Affects
rind
but
does
not
cause
decay
Various types of symptoms
may occur on fruit: hard
spot, virulent spot, freckle
spot and cracked spot
Leaf symptoms are round,
sunken necrotic spots with
grey centres surrounded
by a dark brown ring and
yellow halo (lemon)
Ascospores from dead
leaves on the
orchard floor are
the major source
of inoculum,
whilst conidia are
a minor source
During conidia
germination, a
germtube and an
appressorium are
produced. The
cuticle is
penetrated by a
thin infection peg
(from
appressorium) that
expands into a
mycelium mass
between the
cuticle and the
epidermal wall.
When the fruit
becomes mature
the fungus grows
further into the
rind tissue and
produces a black
spot 6 months after
fruit set
Good agricultural
practices
Pre harvest fungicide
applications
Storage and shipment
in dark, cool
conditions
Kiely 1948
Schüepp 1961
Kotze 1962; 1981;
1996
McOnie 1964; 1967
Whiteside
et al
. 1988
Timmer
et al
. 2000
Ayres 2001
Baayen
et al
. 2002
FFTC 2003
Magarey & Borchert
2003
Obagwu 2003
Agostini
et al
. 2006
Meyer
et al
. 2006
Pascholati
et al
. 2007
EPPO 2009
FABI 2009
Rappussi
et al
. 2009
