Canola crop diseases A Lecture by Mr Allah Dad Khan

2. The Canola Crop Diseases
A
Lecture To ToT trainees ( FFS)
By
Mr. Allah Dad Khan
Provincial Coordinator IPM KPK
MINFAL Pakistan

3. Anthracnose
Colletotrichum higginisianum
Symptoms
• Small circular or irregularly
shaped dry spots which are gray
to straw in color on leaves; a high
number of spots may cause the
leaf to die; lesions may coalesce
to form large necrotic patches
causing leaves to turn yellow and
wilt; lesions may split or crack in
dry centers; dry sunken spots on
roots which enlarge and turn gray
or brown
• Cause
• Fungus

4. Alternaria leaf spot (Black spot, Gray spot)
Alternaria spp.
Symptoms
• Small dark spots on leaves
which turn brown to gray;
lesions may be round or
angular and may possess a
purple-black margin; lesions
may form concentric rings,
become brittle and crack in
center; dark brown elongated
lesions may develop on stems
and petioles
• Cause
• Fungus

5. Cercospora leaf spot (Frogeye leaf spot)
Cercospora brassicicola
Symptoms
• Angular or circular green to
gray spots with brown
borders on leaves; plant
defoliation may occur in the
case of a severe infestation
• Cause
• Fungus

6. Downy mildew
Peronospora parasitica
Symptoms
• Irregular yellow patches on
leaves which turn light
brown in color; fluffy gray
growth on the undersides of
the leaves
• Cause
• Fungus

7. White spot
Pseudocercosporella capsellae
Symptoms
• Small, necrotic, brown spots
on leaf tips or margins that
matures to light gray or
white with the original dark
spot in center; margins of
lesions may be darker;
lesions may coalesce to
form large chlorotic areas
and cause defoliation
• Cause
• Fungus

8. Sclerotinia rot (White mold)
Sclerotinia sclerotiorum
Symptoms
• Irregular, necrotic gray
lesions on leaves; white-
gray leions on stems;
reduced pod set; shattering
seed pods
• Cause
• Fungus

9. Clubroot
Plasmodiophora brassicae
Symptoms
• Slow growing, stunted
plants; yellowish leaves
which wilt during day and
rejuvenate in part at night;
swollen, distorted roots;
extensive gall formation
• Cause
• Fungus

10. Black root
Aphanomyces raphari
Symptoms
• Small black-blue areas on roots
which expand and girdle taproot;
roots become constricted at site
of lesions; black discoloration
extends into root
• Cause
• Fungus
• Comments
• Fungus can survive in soil for
prolonged periods
• Management
• Control depends on crop rotation
with non-brassica species

11. Wirestem (Damping-off)
Rhizoctonia solani
Symptoms
• Death of seedlings after
germination; brown-red or
black rot girdling stem;
seedling may remain
upright but stem is
constricted and twisted
(wirestem)
• Cause
• Fungus

12. Black rot
Xanthomonas campestris
Symptoms
• Seedlings develop wilted
yellow to brown leaves and
collapse; yellow, V-shaped
lesions on mature leaf
margins; dark rings can be
found in the cross section of
the stem
• Cause
• Bacterium

13. Turnip mosaic
Turnip mosaic virus (TuMV)
Symptoms
• Yellow and green mosaic
patterns on leaves; necrotic
areas on leaves;
veinclearing and chlorosis
may occur in older leaves;
black spots and brown
necrotic streaks on stems;
stunted plant growth ond
reduced yield
• Cause
• Virus

14. White rust lbugo candida
Symptoms
• White pustules on
cotyledons, leaves, stems
and/or flowers which
coalesce to form large areas
of infection; leaves may roll
and thicken
• Cause
• Fungus