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Fungal disease

Fungal disease

Causal Organism and Symptoms of Sheath Brown Rot

 Causal Organism of Sheath Brown Rot

  • Causal organism for Sheath brown rot is caused by Pseudomonas fuscovaginae Miyajima

Symptoms  of  Sheath Brown Rot

1. Symptoms appearing at seedling and later stages include discoloration and rotting of sheath. 

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Sheath Brown Rot - Introduction, Distribution and Occurance

Introduction to Sheath Brown Rot

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Pecky Rice

Pecky Rice (Kernel Spotting)

  • Pecky rice is also called as kernel spotting.

Distribution and occurrence of Pecky Rice

  • Single or several florets in the panicle develop brown to reddish-brown spots; grain discolored due to feeding of stink bugs and fungal growth.

Causal Organism of Pecky Rice

Many fungi cause damages

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Grain Rot - Economic Importance, Causal Organism and Symptoms

Economic importance of Grain Rot

There is no exact estimate of losses caused, by this disease but 900,000 ha of rice in North Kyushu Island (Japan) have been infected by the disease.

Causal organism of Grain Rot

The Grain rot disease is caused by Burkholderia glumae.

Symptoms of Grain Rot

1. Bacterial grain rot symptoms appear on seedlings and spikelets.

2. Seedlings raised in boxes turn brown and rot.

3. The glumes (lemma) of infected spikelets are discolored.


Bacterial Leaf Streak - Introduction and Economic Importance

Bacterial Leaf Streak


1. Bacterial Leaf Streak of Rice disease is usually observed during the tillering stage of the rice crop.

2. If the Bacterial Leaf Streak appeared in the later growth stages, the rice plant can easily recover and grain yield losses are minimized.

3. The disease is not reported to occur in temperate countries including Japan. The disease infection reduces the 1000 grain weight to the tune of 32.3%.

Economic importance of Bacterial Leaf Streak

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Pre disposing factors, Alternate host and Management options for Eye Spot

Predisposing factors of Eye spot

Factors that favor the development of Rice Eyespot disease is prolonged leaf wetness.

Alternate Host of Eye spot

Alternate hosts for Rice Eyespot disease are the Cynodon dactylon and Eleusine indica.

Management options of Eye Spot

Rice Eye spot can only be managed by using resistance rice cultivars.

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Causal Organsim and Symptoms of Eye Spot

Causal Organism of Rice Eye Spot disease:

Causal organism for Rice Eyespot disease is "Drechslera gigantea".

Symptoms of Rice Eyespot disease:

1. Small size water soaked spots appear on the leaves and finally, olivaceous dots or rings.

2. A yellow halo frequently appears around young spots but later disappears.

3. Later spots develop into minute, longitudinally elongated, oval lesions with white to straw colored necrotic centres surrounded by narrow, dark brown margins.

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Eye Spot - Introduction and History

Introduction to Eyespot

1. The Rice Eye spot has also been called Brown spot type disease

2. Causal organism for rice Eyespot disease is "Drechslera gigantea'

3. Prolonged leaf wetness favor the development of Rice Eyespot disease.

History of Eye Spot

1. The Rice Eyespot disease was observed on CICA 6 in Colombia, CICA 7 in Panama, and Naylamp in Peru.

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Cultural practices to control Downy Mildew

Cultural practices to control Downy Mildew

The cultural practices to control Rice Downy Mildew disease:

1. Select and use only disease-free seeds for sowing. If possible, procure seeds that are resistant to downy mildew.

2. Transplant only healthy seedlings. Practice crop rotation. After harvest, plough-under all the plant debris.

3. Proper land preparation to make sure that soil is well drained.

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Causal Organism and Symptoms of Downy Mildew

Causal organism of Downy Mildew

The causal organism for Rice Downy mildew disease is Sclerophthora macrospora.

Symptoms of Rice Downy Mildew disease:

1. Downy mildew infection begins as angular yellow spots on the upper leaf surface.

2. Then they turn brilliant-yellow colored spots.

3. Eventually, the internal parts of these spots become brown with yellow margins.

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Introduction and Pre-disposing factors of Downy Mildew

Introduction to Downy Mildew:

1. Rice Downy mildew disease has been reported as one of the most important disease in most of the Rice producing countries in the world.

2. The causal fungus, Scleropthora macrospora. Infects rice plants systematically except root system and causes stunting of the whole plants and mosaic or yellowing of leaves.

3. It has a wide host range in graminaceous plants including wheat, barley, corn, sorghum and various pasture and weed grasses.


Causal Organism and Symptoms of Crown Sheath Rot

Causal organism of Crown Sheath Rot

The causal organism for Crown sheath rot disease is "Gaeumannomyces graminis".

Symptoms of Crown Sheath Rot

The symptoms of Crown Sheath Rot are:

1. Black to brown diffuse lesions on the sheath near the water line, perithecia necks protruding from the upper surface with a thick fungal mat between the leaf sheath and culm.

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Pre-disposing factors and Management Options of Crown Sheath Rot

Predisposing Factors of Crown Sheath Rot

Factors favour the development of Crown sheath rot disease are application of excess nitrogen.

Management options of Crown Sheath Rot:

Crown sheath rot disease management options include cultural practices. Cultural practices of Crown Sheath Rot

Cultural practices for the control of Crown Sheath Rot:

1. Crop rotation with non-grass crops.


Crown Sheath Rot Introduction, Distribution and Occurance

Introduction to Crown Sheath Rot

1. It is also called as Black Sheath Rot.

2. The causal organism for Crown sheath rot disease is "Gaeumannomyces graminis".

3. Black sheath rot or crown rot was considered a minor disease of rice in Texas for several decades, but has become important when intensive infection reported systems.

Distribution and occurrence of Crown Sheath Rot:

The distribution Crown sheath rot is found throughout Louisiana especially severe where excess nitrogen was applied.

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Symptoms and Causal Organism of Black Kernel

Symptoms of Black kernel:

1. Glumes are discolored.

2. In severe infection, the rice kernel shows black discoloration.

Causal Organism of Black kernel

1. Causal organism of Black kernel disease is Curvularia Boedijn.


Black Kernel Introduction, History and Economic Importance

Introduction to Black kernel

  • Several species of Curvularia are found on rice grains causing discoloration, and a few of them mould the grain and may even cause leaf spots under certain conditions.
  • It is a minor disease.
  • Black kernel disease infected glumes are discolored.

History of Black kernel

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Cultural practices for control of Aggregate sheath spot:

Cultural practices for control of Aggregate sheath spot:

1. Burning of crop residues after harvest provides the most effective control for this disease.

2. Complete removal of infected crop residues also minimizes carryover of the inoculum.

3. Moldboard ploughing, crop rotation, or fallowing also minimizes carryover inoculum.

4. Avoid dense rice stands as they may enhance disease development.

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Symptoms, Causal Organism and Pre-disposing factors of Aggregate Sheath Spot

Symptoms of Aggregate sheath spot

1. Aggregate sheath spot lesions appear on the lower leaf sheaths at the water line during the tillering stage.

2. Lesions are circular to elliptical with gray-green to straw-colored centers surrounded by distinct brown margins.

3. Frequently, additional margins are formed around the initial lesion thus producing a series of concentric bands.

4. A strip of light-colored necrotic cells runs down the lesion center.

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Aggregate sheath spot introduction, distribution and occurance

Introduction to Aggregate sheath spot 

1. Aggregate sheath spot produce lesions, which are circular to elliptical with gray-green to straw-colored centers surrounded by distinct brown margins.

2. Aggregate sheath spot is caused by the fungus Rhizoctonia Oryzae-sative

3. The fungus produces glabose sclerotia on the surface of infected rice leaf sheath as well as cylindrical selerotia inside the cell of infested tissue.

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Management Options for control of Udbatta Disease

Udbatta disease management options include

  • cultural practices,
  • chemical control and

Cultural practices of Udbatta disease

  • Use disease free seeds for sowing. Hot water seed treatment at 540C for 10 minutes.
  • Removal and destruction of diseased panicles in field.

Chemicals for the control of Udbatta disease.

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