Agriculture Reference
In-Depth Information
SUMMER
Leaf lesions may
be circular when
between veins and
angular when
bordered by veins.
Disease
develops on first
fully expanded
leaves near soil.
Any cell can germinate. Conidia
germinate in presence of free water
and may penetrate tissues directly or
through stomata or wounds.
LATE
SUMMER
SPRING
There are multiple
cycles per season.
Conidia are
dispersed by
wind and rain
splash.
Secondary spread of conidia
to neighboring leaves and
plants is important in the
spread of the disease.
Early blight is
prevalent on
senescing tissue
and plants
stressed from low
nitrogen and pest
pressure.
Spores are
produced on
infested plants
and plant debris
between
41
and
86
ºF, Sporulation
is favored by
alternating wet
and dry periods.
Early blight disease cycle
FALL
Tu bers are inoculated during
harvest. Circular, sunken lesions
form on infected tubers.
Pathogen survives winter in
infested potato plant debris.
WINTER
Fig. 11.9.
The disease cycle of the early blight pathogen,
Alternaria solani
.
Protectant fungicides should be applied ini-
tially at relatively long intervals, and subse-
quently at shorter intervals as the crop ages.
caused by
P. erythroseptica
(Taylor
et al
., 2004;
Fitzpatrick-Peabody and Lambert, 2011), and
silver scurf caused by
H. solani
(Rodriguez
et al
.,
1996; Errampalli
et al
., 2001; Miller
et al
., 2004,
2011). In addition, bacteria causing soft rot can
impact postharvest, especially when harvest
conditions are wet (Elphinstone and Perombe-
lon, 1986; Perombelon, 1992; Toth
et al
., 2003,
2011; De Boer
et al
., 2007; Fiers
et al
., 2012). In
the field, tubers may be wounded during har-
vest, transport to storage, and during storage ac-
tivities. The duration of this process, depending
on the distance of the field to the storage (up to
150 km in Michigan, USA) and the handling
capacity of the system, can take up to
24
h dur-
ing September-October in temperatures ranging
from
15
to 25°C, especially when equipment
breaks down (Gachango
et al
., 2012a).
Currently, the primary control for these dis-
eases in storage facilities includes the elimination
Epidemiology and management
of postharvest diseases
Potato growers aim to produce and harvest a
healthy and high-quality crop. However, there
are several diseases that infect potatoes in
storage, thus compromising their quality and
creating a potential economic loss (Secor and
Gudmestad, 1999). The major storage diseases
include late blight caused by
P. infestans
, dry rot
caused by
F. sambucinum
and
Fusarium
spp. (Se-
cor and Salas, 2001; Peters
et al
., 2008a,b;
Gachango
et al
., 2012a), Pythium leak caused
by
P. ultimum
(Gudmestad
et al
., 2007), pink rot
