Questions and Answers
What is the primary pathogen responsible for Brown Spot disease in crops?
Which chemical is NOT recommended for spraying in the nursery to combat the Brown Spot fungus?
How do the conidia of the pathogen associated with Brown Spot appear?
What effect does ophiobolin A have on plant cells?
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In which temperature range is the development of Brown Spot disease most favorable?
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What is a visible symptom of Brown Spot disease on affected plants?
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What is the sexual stage of the fungus that causes Brown Spot?
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Which of the following conditions enhance the severity of Brown Spot disease?
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What is the primary pathogen responsible for the blast disease in rice?
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Which symptom is specifically associated with neck blast in rice?
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What is the impact of the blast disease on rice yields depending on the stage of infection?
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What is the appearance of conidia produced by Pyricularia oryzae?
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Which environmental condition is NOT favorable for the development of blast disease?
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What type of lesions appear on the leaves affected by leaf blast?
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Which part of the rice plant does nodal blast affect most significantly?
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What is the perfect state of Pyricularia oryzae called?
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What is the primary mechanism by which the fungus causing false smut spreads?
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Which of the following conditions favor the growth of the pathogen responsible for poorly filled grain?
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How long can the pathogen survive in dry soil?
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Which management practice is recommended to control the pathogen effectively?
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What are the visible symptoms caused by the fungus Ustilaginoidea virens?
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Which of the following is NOT a recommended practice for managing the pathogen?
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What is the primary secondary source of infection for the false smut pathogen?
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Which variety of plants is recommended for resistance against the pathogen affecting grain filling?
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What are the visible symptoms of Udbatta disease on ear heads?
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What type of treatment is effective against the Udbatta disease pathogen?
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Which pathogen is associated with Stackburn disease?
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What characteristic symptom appears on leaves affected by Stackburn disease?
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What effective method can control Kernel Smut disease?
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What visible condition do grains exhibit due to Kernel Smut infection?
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What is a common management practice for controlling Stackburn disease?
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What is the shape and structure of conidia related to Stackburn disease?
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What types of conidia are produced by the fungus associated with grain discoloration?
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Which of the following phytotoxins is produced by the pathogenic fungus causing grain discoloration?
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What is the recommended treatment for seeds to manage the fungal infection?
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What color discoloration might grains exhibit due to infection before or after harvesting?
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What environmental conditions favor the spread of fungal disease in grains?
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Which of the following grains is primarily affected by the pathogens mentioned in the document?
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During which growth stage should crops be sprayed to prevent grain discoloration?
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What moisture content is ideal for storing grains to prevent fungal infections?
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Study Notes
Fungal Diseases of Rice
Blast - Pyricularia oryzae
- Affects rice at all growth stages, causing lesions on leaves, nodes, rachis, and glumes.
- Leaf symptoms include spindle-shaped spots with grey centers and dark brown margins.
- Severe infections lead to brown-black lesions on nodes (nodal blast) and neck rot during flowering.
- Yield losses range from 30% to 61% depending on infection timing.
- Favourable conditions: High humidity (93-99%), low temperatures (15-20˚C).
- Management includes fungicides like carbendazim and tricyclazole.
Brown Spot - Helminthosporium oryzae
- Attacks from seedling to milky stages with spots on leaf blade, sheath, and glume.
- Dark brown spots with yellow halos eventually coalesce, causing leaf dieback.
- Leads to reduced grain quality and diminished germination.
- Favourable conditions: 25-30˚C temperature and over 80% humidity.
- Manages via resistant varieties and organic amendments.
False Smut - Ustilaginoidea virens
- Transforms grains into greenish spore balls, affecting only some spikelets in a panicle.
- Spherical, warty chlamydospores form as spore balls.
- Depends on grassy alternate hosts for its life cycle.
- Favoured by rainfall and cloudy weather during flowering.
Udbatta Disease - Ephelis oryzae
- Symptoms appear at panicle emergence, causing black spike-like structures.
- Spikelets get reduced in size, cemented by fungal mycelium and covered by greyish stroma.
- Management through hot water seed treatment at 45˚C for 10 minutes.
Stackburn Disease - Trichoconis padwickii
- Affects leaves and ripening grains with circular to oval spots with dark margins.
- Glumes show reddish-brown spots; kernels shrivel and become brittle.
- Conidia are elongated, thick-walled, and septate.
- Management includes seed treatment with fungicides and hot water treatment.
Bunt or Kernel Smut - Tilletia barclayana
- Characterized by black pustules or streaks forming on grains, which burst at ripening.
- Fungal spores can replace grains partly or wholly.
- Both macroconidia and microconidia are produced, with the fungus releasing non-host-specific phytotoxins.
- Management via seed treatment with fungicides.
Grain Discoloration - Various Pathogens
- Various fungi cause grain discoloration, leading to quality losses.
- Symptoms include dark brown or black spots; discoloration can vary in color.
- Favourable conditions include high humidity and cloudy weather during heading.
- Prevention methods include timely spraying and moisture control in grain storage.
Bacterial Diseases of Rice
Bacterial Leaf Blight - Xanthomonas oryzae pv. oryzae
- Symptoms generally occur at heading but can emerge earlier.
- Initial lesions are water-soaked, leading to yellowing and drying of leaf tips.
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Description
Test your knowledge on the fungal diseases affecting rice, particularly focusing on Blast caused by Pyricularia oryzae. This quiz covers symptoms, stages of infection, and the impact on crop growth. Understand the significance of detection and management for better yields.