Brassica Flashcards
Alternaria black spot
Alternaria brassicicola
All aboveground parts of the plants are
affected.
Lesions on leaves start as small, dark spots
that gradually enlarge and turn brown to gray
with concentric zones resembling that of a
target.
Alternaria brassicicola
Remove volunteer and weedy crucifers that
may serve as alternate hosts for the
pathogen.
Spray with copper-based fungicides.
Alternaria brassicicola
Choanephora wet rot
Choanephora cucurbitarum
Affected flowers, pedicel, fruits
Become water soaked,
Fruit resembling a pincushion with black pins
Choanephora cucurbitarum
Flowers are covered with white then purplish
black fungal growth.
❑ An entire fruit can rot in a 24- to 48-hour
period.
Choanephora cucurbitarum
Flowers are covered with white then purplish
black fungal growth.
❑ An entire fruit can rot in a 24- to 48-hour
period.
Choanephora cucurbitarum
Fungicides
are
ineffective
against
Choanephora wet rot because new blossoms
or flowers open every day.
❑ Practice crop rotation.
❑ Avoid overhead irrigation.
Choanephora cucurbitarum
Black rot
xanthomonas campestris pv. Campestris
Infected plants first exhibit 1-3cm irregular dull yellow lesions along the leaf margin
Expands to midrib forming a V shape
xanthomonas campestris pv. Campestris
Plasmodiophora brassicae
Club root
Plasmodiophora brassicae
Club root
Swelling and injury of roots and hypocotyl, roots of infected plants
Forms galls
Plasmodiophora brassicae
Plants yellowed and became stunted due to root clubbing
Plasmodiophora brassicae
Increase soil pH to above 7.0 by lime
application to reduce symptom severity or
root clubbing.
❑ Calcium and Boron application can also
reduce root clubbing.
❑ Avoid furrow irrigation
Clubroot
Black leg
Phoma lingam
Affects every plant part
Irregular shaped lesions on leaves
With necrotic gray spots
Phoma lingam
Black, pinpoint pycnidia that exude pink spore
mass
under
favorable
moisture
and
temperature are produced on the affected
areas.
Initial symptom on stem includes blackened
xylem.
Black leg
Remove volunteer and weedy crucifers that
may serve as alternate hosts for the
pathogen.
Phoma lingam
Bacterial sof rot
Erwinia carotovora var. Carotovora
Early symptoms appear as water-soaked lesions
and expand rapidly.
❑ P. marginalis causes a wet, slimy soft rot and
unpleasant smell.
Bacterial soft rot
