Canola crop diseases A Lecture by Mr Allah Dad Khan
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Transcript of Canola crop diseases A Lecture by Mr Allah Dad Khan
The Canola Crop Diseases A
Lecture To ToT trainees ( FFS)
By Mr. Allah Dad Khan
Provincial Coordinator IPM KPK
MINFAL Pakistan
AnthracnoseColletotrichum 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
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
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
Downy mildewPeronospora parasitica
Symptoms
• Irregular yellow patches on leaves which turn light brown in color; fluffy gray growth on the undersides of the leaves
• Cause• Fungus
White spotPseudocercosporella 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
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
ClubrootPlasmodiophora 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
Black rootAphanomyces 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
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
Black rotXanthomonas 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
Turnip mosaicTurnip 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
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