2. Club root of crucifers: Plasmodiophora brassicae
• Finger and toe disease. cabbage, cauliflower
• Shows pale green to yellowish leaves initially.
• Shows wilting in the middle of hot, sunny days, recovering during
the night.
• Stunting and reduction in size of heads.
• Characteristic symptoms become apparent in advanced stage of
root infection as spindlelike, spherical, knobby, or club-shaped
swellings.
• The swellings may be few, or they coalesce and cover the entire
root system
4. Management
• Use of seedlings from disease free fields
• Plant cabbage and other susceptible cruciferous crops in well
drained fields that have a pH slightly above neutral (usually about
pH 7.2)
• Add hydrated lime to soil to increase pH to 7.2 ( 6weeks before
planting @2.5T/ha)
• Avoid excess irrigation
• Treat the soil of seed bed areas with chloropicrin, methyl bromide
or vapam two weeks before planting. Drenching soil with a solution
of Brassicol (Pentachloronitrobenzene)
5. Downy Mildew – Peronospora parasitica
• Raddish, cabbage, cauliflower, mustard, and knol-khol.
• Yellowish spot on leaves-later brown dead patches.
• White to grey cottony coat beneath the spots, on the underside of
leaf.
• Defoliation.
• Dwarfing or killing of young shoots flowers, fruits.
• In cabbage, these spots expose the heads to soft rot.
• Cauliflower curds look brownish at the top.
6. Etiology
• Peronospora parasitica (Pers.) Fr.
• Mycelium strictly intercellular with large, finger-shaped intracellular
haustoria which become clavate and branched and nearly fill the
cell cavity.
7. Management
• Destruction of infected plant debris.
• Avoidance of thick sowing and excessive moist conditions.
• Heat treatment of seeds at 43 – 50⁰C for 20 minutes and treating
them with Apron metalaxyl + mancozeb (0.3%) is also effective.
• Spray metalaxyl@0.25% or COC@ 0.3% or Mancozeb@ 0.2% at 10
days interval
8. Alternaria leaf spot- Alternaria brassicola, A.
brassicae and A. raphani
• Cabbage, cauliflower and mustard.
• Spots are small, dark coloured.
• They enlarge, soon become circular & 1mm. in diameter
• Under humid conditions groups of conidiophores will be formed in
the concentric rings spot
• The spots coalesce leading to blighting of leaves.
• The fungus is seed borne and cause shriveling of seeds and poor
germination.
• Linear spots also appear on petioles, stems, pods & seeds
9. Etiology
• A. brassicicola (Schw.) Wiltshire, A. brassicae (Berk.) Sacc. and A.
raphani Groves & Skolko.
Conidia of bigger size with larger beak.
• Mycelium is immersed, hyphae branched, septate, hyaline.
• Conidiophores are simple, erect, bearing one to several small but
distinct conidial scars.
•Mycelium immersed, hyphae branched
septate, hyaline at first, later brown or
olivaceous brown.
Attacks on radish
•Conidiophores are simple or
occasionally branched, septate and
olivaceous brown in colour.
Produces smaller conidia with shorter beak.
10. Management
• Use disease free seeds.
• Collect and destroy the infected plant debris.
• Hot water treatment at 50⁰C for 30 min.
• Seed treatment with agrosan.
• Foliar spray with Mancozeb@0.2% or COC@ 0.3% twice.
11. Black rot - Xanthomonas campestris pv.
campestris
• Appear near the leaf margins as chlorotic or
yellow (angular) areas.
• The yellow area extends to veins & mid rib
forming characteristic ‘v’ shaped chlorotic
spots.
• Veins and veinlets turn brown and finally black.
• Later infection may reach the roots system and
blackening of vascular bundles occur.
• Bacterial ooze can also be seen on affected
parts
• Early infection- the plants wilt and die
• Late infection- plant succumb to soft rot &die
12. Etiology
• Xanthomonas campestris pv. campestris (Pammel) Dowson.
• Small, rod shaped, aerobic, gram negative, non-spore forming
bacterium.
• The bacterium is monotrichos .
• It produces a yellowish extracellular polysaccharide (EPS)
called Xanthan on media containing glucose.
13. Management
• R.V: Cabbage: Cabaret, Defender, Gladiator, Pusa Muktha
• Cauliflower: Pusa ice, Pusa snow ball-K-I-F, Sel-12.
• ST with Agrimycin or Aureomycin 0.01%
• Hot water treatment at 50⁰C for 30 min for killing seed borne
inoculum followed by a 30 min dip in Streptocycline 100ppm
• Spray Agrimycin-100 or Streptocycline-50 ppm at transplanting,
curd formation and pod formation.
• Crop rotation for 2-3 yrs with non cruciferous crop.
• Drenching seed bed with 5% formalin or any antibiotic solution in
nursery beds.
14. White rust - Albugo candida
Common in Radish
• White, shiny raised blisters (pustules) on the lower surfaces of
leaves, stems & flowers.
• Pustules coalesce to form irregular patches
• The epidermis ruptures exposing white spore mass which gives the
pustule a powdery appearance.
• Distortion of the floral parts including petals, pistils and anthers due
to hypertrophy and hyperplasia.
• Plants malformed beyond recognition.
15. Etiology
• Albugo candida (Pers. Ex Chev.) Kuntze.
• An obligate parasite reproducing both sexually and asexually.
• intercellular and non-septate.
• Numerous short conidiophores arise from the mycelium, which are
arranged in rows beneath the host epidermal layer press on the
epidermis to cause the pustule/ blister.
• Inside the pustules, sporangia are produced in chains arising from
the sporangiophores at the base of the cavity.
• The sporangia are hyaline, spherical, thick walled, hyaline and
interconnected by a pad of gelatinous disc like tissue.
• The oospore is spherical with a thick irregular wall, deep yellow to
dark brown in colour.
16. Management
• Practices like collection and burning of diseased plant material
in order to prevent oospore formation.
• Sanitary measures.
• Crop rotation.
• Destruction of weeds.
• Spray 0.8% any copper fungicide.
17. CAULIFLOWER MOSAIC
• Vein clearing or banding symptoms are produced on the leaves
ultimately leading to mosaic pattern .
• Only the young leaves are affected initially in which light green
patches appear.
• Early infection may cause reduction in plant growth leading to
stunted look.
18. Etiology
• The disease is caused by Cauliflower Mosaic Virus which
belongs to caulimovirus (CaMV) group.
• Virions are isometric, 50 nm in dia. and non-enveloped and
the genome consists of unipartite double stranded DNA.
19. Management
• Control of aphid vectors through the use of
insecticides like Metasystox (0.1%) at an appropriate
stage is helpful in reducing the spread of the disease.
