Agriculture Reference
In-Depth Information
Host crops
c
Conditions for
Conditions
Disease and
and
Infection
spore
for
Cultural
Special
pathogen
a
distribution
d
Symptoms
sources
production
infection
Fungicides
Resistance
control
features
Purple blotch
b
,
O, g, j, l
2-3mm watery
Debris,
Light, RH
25°C, free
Dithiocarbamates, Cv. differences
Long rotation,
Often in disease
Alternaria porri
lesions on leaves infected
> 90%, spore
water on leaf
iprodione,
hygiene,
complex with
(see Plate 6A)
Tr, st
and flower stalks bulbs
release with
for 6 h, older
mancozeb,
minimize leaf
Stemphylium
vesicorum
1,2,3
,
which elongate
RH drop, 25°C
and damaged
chlorothalonil,
wetness by
and bleach, with
optimal, little
leaves more
vinclozolin,
wide spacing,
saprophyte fungus
purple/brown
at < 13°C
susceptible
vary fungicides
moderate N,
Aureobasidium
centres, rot of
(e.g. by thrips)
to avoid resistant
high P and K
pullulans
on leaves
infected bulbs
pathogens
lessens infection
Leaf fleck, leaf
O, wide host
Small leaf
Debris, nearby
Can occur at
Plants
As for
Avoid crop
Worsened by
spot, collar rot,
range
spots, rot round
crops, sclerotia
low temp. (5°C)
stressed by
B. squamosa
overlap,
ozone damage
Botrytis cinerea
pseudostem
in soil
cold (collar
hygiene
(see Plate 2)
Te
with grey mould
rot)
on it
Leaf blight
b
, blast,
O
Small, round
Sclerotia in
14-20°C, free
6-28°C, free
Dithiocarbamates, J, c,
A. roylei
Avoid crop
Forecasting
Botrytis squamosa
to ellipsoid
debris and
water for
water on
benzimidazoles
from which
overlap,
models made,
(see Plates 2 & 6B) Te
white lesions
soil which
> 12 h, spore
leaf for > 6 h,
resistance is
hygiene,
worsened by
with pale halo,
form conidia
release with
old and
being
promote air
ozone damage,
leaf die-back
(spores), nearby
RH change
senescent
transferred
movement and
resistance to
from tip,
crops
leaves
to onion
leaf drying by
benzimidazole
sporing on
susceptible
wide spacing,
fungicides
dead leaves
rotation
reported
Leaf spot,
O, g, s and
Leaf spots
Debris,
Warm and wet
Warm and wet
Protectant
Rotation,
Cercospora
many allium
with red edges,
volunteers,
fungicides
remove allium
duddiae
hosts
brown spore
wild alliums
routinely
weeds
St, tr
masses
applied -
captan, maneb,
Bordeaux
mixture,
