Phytophthora blightPhytophthora blight
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C. O.: Phytophthora parasitica var. sesame
Symptoms:
• Disease can attack at all stages of the plant.
• Initial symptom is water soaked spots on lower leaves and stems.
• The spots are chestnut brown in the beginning later turn to black.
• Brownish spots spreads rapidly both upward and downward and also around stem.
• Discoloration of distant near the base of the stem adjusts to the soil.
• In humid condition white woolly fungus growth observed. The seeds remain shivered in case of severe attack.
• Premature leaf fall occurs and plant died.
Management:
• Follow two year crop rotation.
• Deep summer ploughing.
• Provide good drainage.
• Late planting
• Use resistant tolerant varieties like TKG-22, TKG-55 and JTS-8.
• Intercropping system, Sesamum + pearl millet(3:1) should be followed
• Destruction of crop debris.
• Rougue out diseased plants.
• Soil amendment with biological control agent like Trichoderma harzianum and Trichoderma viride or seed treatment with T. harzianum/ T. viride / Bacillus subtilis (0.4%)
• Seed treatment before sowing with Apron 35 SD(0.3%) or Thiram (0.3%) .
• For root/stem infection, drench soil 2-3 times with Ridomil MZ (0.25%) along with diseased plants at 7 days interval.
• Spray crop 3 times with Ridomil MZ (0.25%) or Mancozeb (0.20%) or copper oxychloride (0.25%) at an interval of 10 days from the initiation of disease.
Wilt Wilt
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C.O.: Fusarium oxysporum f.sp.sesami
Symptoms;
• The plant gets infected at any stage of crop development.
• Symptoms are first visible in the lower leaves and then it progresses upwards.
• Yellowing, drooping and desiccation of leaves occur.
• In severe case, entire plant gets defoliated, bends down and ultimately dries up.
• Vascular bundles turn brown starting from root and gets extended up to tip.
• Root does not rot.
Management:
1. Destruction of wilted plants
2. Use resistant varieties like JT-7, N-32, MB-12
3. Crop rotation
4. Seed treatment with thiram (0.3%) or carbendazim (0.15%)
Cercospora leaf spot Cercospora leaf spot:
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C. O.: Cecospora sesamicola
Symptoms:
• Leaf spot arre angular and 1 to 8 mm in size.
• Initially chlorotic lesion on upper surface and later become dark brown.
• Disease appears as small, angular brown leaf spots of 3 mm diameter with gray centre and dark margin delimited by veins.
• In severity of the disease defoliation occurs.
• Under favourable conditions, the disease spreads to leaf petiole, stem and capsules producing linear dark coloured deep seated lesions.
Management:
• Grow resistant/tolerant variety like TKG-21.
• Early planting i.e. immediately after onset of monsoon.
• Follow intercropping system of sesamum + pearl millet (3:1).
• Destruction of plant debris
• Treat the seed with Thiram (0.15%) + Bavistin (0.05%) in 1:1 ratio.
Three sprays Topsin M(0.1%) or Zineb (0.25%) or mancozeb (0.25 %)as and when disease appears, at 15 days interval.
Powdery mildewPowdery mildew:
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C. O.: Oidium sp. Sphaerotheca fudiginia, Leveillula
Symptoms:
• Small cottony spots appear on the infected leaves which gradually spread on the lamina.
• Defoliation of severely infected plant occurs before maturity.
Management:
• Field sanitation.
• Destruction of crop residues.
• Early planting i.e. immediately after onset of monsoon.
• Follow intercropping system of sesamum + pearl millet (3:1).
• Use resistant variety RT-127
• Destruction of crop residues and alternate hosts.
• Foliar spray (2 to 3) of wettable sulphur (0.2%) as and when disease appears, at 10 days interval
Stem and root rotStem and root rot
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C.O.: Rhizoctonia bataticola (Macrophomina phaseolina)
Symptoms:
• The affected plants show wilting.
• At ground level stem becomes black which extends upward rupturing the stem.
• Black dots appear on the infected stem which are the pycnidia of the fungus.
• If wilted plant is uprooted, black coloured roots are observed having sclerotia of the fungus and looks as if charcoal is sprinkled on the root.
• The roots become brittle.
• In diseased plants black pods are seen which open prematurely exposing shriveled and discoloured seeds
Management:
• Deep summer ploughing.
• Provide good drainage.
• Late planting.
• Do crop rotation or change the field after every two years.
• Follow intercropping system sesamum + mothbean 1:1 or 2:1 ratio.
• Whenever necessary, irrigate field every two weeks to avoid stress condition.
• Use resistant varieties.
• Destruction of crop residues.
• Soil incorporation of biological control agents like Trichoderma harzianum, Trichoderma viride.
• Treat the seed with T. viride or T. harzianum or Bacillus subtilis (0.4%)
• Seed treatment with Thiram 75 SD (0.15%)+Bavistin (0.05%) 1:1 or Thiram 75 SD (0.3%).
• On appearance of the disease, drench soil with Thiram + Bavistin (1:1) along with diseased plants at 7 days interval.
Alternaria Leaf spotAlternaria Leaf spot:
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C.O.: Alternaria sesami
Symptoms:
• The pathogen attacks all parts of the plant at all stages.
• Small, dark brown water soaked, round to irregular lesions, with concentric rings, 1-8 mm in diameter appear on the leaves and under excessive atmospheric and soil humidity the spot increases in size and number.
• The lesions may also appear on the midrib and veins of the leaves.
• Milder attacks cause only defoliation, in severe cases the plant may die.
Management:
• Grow resistant/tolerant variety like Krishna.
• Destruction of crop residues and weeds.
• Early planting i.e. immediately after onset of monsoon.
• Follow intercropping system of sesamum + sunflower (3:1).
• Treat the seed with thiram (0.15%) + Bavistin (0.05%) in 1:1 ratio.
• Three sprays Mancozeb (0.20%) as and when disease appears, at 15 days
Bacterial blightBacterial leaf spot
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C.O.: Pseudomonas syringae pv. Sesame
Symptoms:
• Light brown angular spots with dark purple margin appear in the leaf veins.
• Defoliation and death of plant may occur in severe leave and stem infection.
• Sunken and shiny spots are appeared on the capsules.
• Early capsule infection renders them black and seedless.
Management:
• Use white seeded early varieties.
• Crop rotation.
• Use resistant varieties.
• Destruction of crop residues.
• Seed treatment with hot water at 52o C for 10 minutes
• Steep the seed in Agrimycin-100 (250 ppm) or Streptocycline suspension (0.05%) for 30 minutes.
• Foliar spray of Streptocycline (500 ppm) as soon as symptoms are noticed.
• Continue two more sprays at 15 days interval if necessary.
Sesamum phyllodySesamum phyllody:
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C.O.: Phytoplasma like organism
Symptoms:
• All floral parts are transformed into green leafy structures.
• In severe infection, the entire inflorescences is replaced by short twisted leaves.
• The internodes are shortened and plants is stunted and branching is abnormal thus gives bushy appearance.
• Sepals are transferred into green leafy structure and flower is sterile.
• The overy also malformed into elongated structure like shoot.
• Finally plants look like witches broom.
Management:
• Remove all the reservoir and weed hosts.
• Carefully periodically rouging the infected plants. Late sowing.
• Spraying of systemic insecticides like Cartep hydrocarban or Methyl-O-demeton (Metasystox 10ml/10 lit. water
Bacterial blight
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C.O.: Xanthomonas campestris pv. Sesame
Symptoms:
• Plants of all stage is affected.
• Water soaked, small and irregular spots are formed on the leaves which later increases and turn brown, under favourable conditions.
• Leaves become dry and brittle, severely infected leaves defoliate.
• Later, the spots are formed on the twigs, which bear poor capsules.
Management:
• Crop rotation.
• Use resistant variety like T-58
• Early planting i.e. immediately after onset of monsoon.
• Destruction of crop residues.
• Seed treatment with hot water at 52 o C for 10 minutes.
• Steep the seed in Agrimycin-100 (250 ppm) or Streptocycline suspension (0.05%) for 30 minutes.
• Foliar spray of Streptocycline (500 ppm) as soon as symptoms are noticed.
• Continue two more sprays at 15 days interval if necessary.
