| Crop | Rice(Oryza sativa) |
| Disease | Brown Spot/Sesame Leaf Spot |
| Pathogen | A: Helminthosporium oryzae/Bipolaris oryzae S: Cochliobolus miyabeanus |
| Group | Fungi (Ascomycota) |
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A denotes Asexual reproductive stage (Anamorph) and
S denotes Sexual reproductive stage (Teliomorph).
Brown spot/Sesame leaf spot symptoms. Image modified from IRRI - Rice Knowledge Bank "Brown Spot". (CC BY-NC-SA 3.0).
- The disease first appears as minute, sesame shaped, rectangular brown spots. Later these spots become cylindrical or oval to circular spots with yellow halo.
- Several spots coalesce and the leaf dries up.
| Bengal famine of 1943 occurred due to the incidence of this disesase. |
| Pathogen | A: Helminthosporium oryzae/Bipolaris oryzae S: Cochliobolus miyabeanus |
| Mycelium | Brown colored, septate |
| Asexual reproduction | Conidia : Borne singly on conidiophore. Spindle shaped or worm like. Brown coloured and germinate at both ends (Bipolaris).They are multiseptate (8 to many celled). No asexual fruiting body |
| Sexual reproduction | Ascus and Ascospores : Long and fusiform. (In Perithecium). |
| Reproductive Structures | ||
| Mode | Spore | Fruiting Body |
| Asexual | Conidia | Nil |
| Sexual | Ascospore | Perithecium |
| Favorable Conditions | 25-30°C, RH >80% |
| Primary spread | Infected seeds |
| Secondary spread | Air-borne conidia |
| Collateral Hosts | Leersia hexandra, Echinochloa colonum |
| Kingdom | Fungi |
| Division | Ascomycota |
| Class | Dothideomycetes |
| Order | Pleosporales |
| Family | Pleosporaceae |
| Genus | Cochliobolus |
| Species | Cochliobolus miyabeanus |
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Organic Hot Water Treatment Hot water seed treatment (53-54°C) for 10-12 minutes before sowing | |
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Fungicide Mancozeb Spray : 2.0g / litre of water, 2-3 times @ 10-15 days interval | |
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Fungicide Edifenphos Spray : 1mL / litre of water, 2-3 times @ 10-15 days interval | |
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