Agriculture Reference
In-Depth Information
Host crops
Conditions for
Conditions
Disease and
and
Infection
spore
for
Cultural
Special
pathogen
a
distribution
Symptoms
sources
production
infection
Fungicides
Resistance
control
features
White tip of leek
b
,
O, g, l, r
White lesions
Soil-, rain-
Leaf contact
Chlorothalonyl
Resistance genes > 3 year rotations
Serious in
Phytophthora porri
3
5 cm,
splashed
with water
and metalaxyl,
in some cvs
overwintered
(see Plate 7A)
Te
particularly at
oospores
6
,
associated
mancozeb and
and landraces
crops, oospores
leaf tips, bulb
infected leaves
with rain,
metalaxyl
survive > 5
rot of o and r
120 DD
months in soil
(>3°C)
from infection
to lesions
6
Onion rust, leek
O, s, g, j, l, gh, c
White flecks
Nearby crops,
10-24°C, > 4 h Maneb, zineb,
Partial in some
Avoid crop
Worse on stressed
rust
b
,
Puccinia
with orange
debris
at RH > 97%
fenpropimorph
l cvs, improved
overlap,
plants, disfiguring
allii
, different
Te, st, tr
pustules of
(for leeks)
by selection in j
7
hygiene, 4-5
on crops harvested
strains for onion
uredospores,
year rotation
leafy
and leek
1-3 mm long
(see Plates 2
and 7B)
Black (stalk) mould, O, l and many
Spots, then
Debris, possibly
Cool, moist
Attack by
As for downy
Cv. differences
Hygiene, avoid
Often secondary,
Stemphylium
hosts
browning and
infected seed
conditions
other
mildew or
crop damage
invading tissue
botryosum
,
black mould,
pathogens,
Botrytis
which creates
damaged by
sexual stage
Te, st
collapse of leaf
e.g.
Botrytis
necrotic tissue
downy mildew
forming
or seed stalk
or mildew
or
Botrytis
ascospores,
Pleospora
herbarum
