Agriculture Reference
In-Depth Information
Table 5.6.
Fungal diseases of allium vegetables infecting from the soil.
Temp.
Temp.
Host range
a
Control
b
Disease
Pathogen
(optimum, °C) (range, °C)
White rot (see
Sclerotium
All allium
14-18
9-24 for
Fu, so, f, at
Plates 2 and 8a)
cepivorum
crops
sclerotial
germination;
5-29 for
mycelial
growth
Pink root (see
Pyrenochaeta
O, g, s, l
24-28
16
Rv, ro, fu, so, at
Plate 8b)
terrestris
Fusarium
basal
Fusarium
O, g, j, r
28-32
15-32
Rv, ro, fu, so, at
rot (see Plate 8c)
oxysporum
;
f. sp.
cepae
;
f. sp.
allii
Garlic and leek
Fusarium
L, g
root and
culmorum
basal rot
Southern blight
Sclerotium
O, g, l, j, s and
27-30
15
Fu, so
rolfsii
many other spp.
Damping off
Fusarium
spp.;
All allium crops Wide range
Fu, so, at
Pythium
spp.; and many
Rhizoctania
spp. other spp.
and
R. solani
a
O, onion; g, garlic; s, shallot; l, leek; j, Japanese bunching onion; r, rakkyo.
b
Fu, fumigation; so, solarization; f, fungicide; at, avoidance by timing; rv, resistant
cvs; ro, rotation.
climates, diseases of cool temperatures like white rot may attack winter crops
and diseases of warmer temperatures afflict summer crops.
Changes in cultural practices can influence root diseases, often in an
unexpected fashion. A good example is the effect of flood control in Egypt on
white rot following the building of the Aswan dam. Previous to this, the fields
used for onion production had been subject to several weeks of flooding, followed
by a baking, with temperatures as high as 39°C at 5 cm, as the soil dried out.
This, together with the annual deposit of fresh silt from the flood waters,
prevented white rot. After floods were prevented, severe white rot led to a more
than 50% decrease in winter onion production and a large decline in exports.
Further details of particular diseases
White rot
White rot is one of the most devastating and important diseases of allium
vegetables. The fungus penetrates the root epidermis and invades the root
