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Diseases

Diseases
27
Jul

Management Practices for Control of Sheath Rot Disease

1. Removal of infected stubbles after harvest and optimum plant spacing are among the cultural practices that can reduce the disease.

2. Application of potash at tillering stage is also recommended. Foliar spray of calcium sulfate and zinc sulfate was found to control sheath rot.

3. At booting stage, seed treatment and foliar spraying with carbendazim or mancozeb was found to reduce sheath rot.

4. Foliar spraying with benomyl and copper oxychloride were also found to be effective.

File Courtesy: 
RARS, Karjat
27
Jul

Symptoms of Sheath rot disease

1. Infection occurs on the uppermost leaf sheath enclosing the young panicles at late booting stage.

2. Initial symptoms are oblong or irregular spots or lesions, 0.5-1.5 cm long, with dark reddish brown margins and gray centre.

3. Lesions may also consist of diffuse reddish brown discoloration in the sheath.

4. Lesions enlarge and often coalesce and may cover the entire leaf sheath.

File Courtesy: 
RARS, Karjat
Photo Courtesy: 
http://www.ipmimages.org/browse/detail.cfm?imgnum=5390497
27
Jul

Details of Sheath rot disease

Period of occurrence of Sheath rot disease: The disease is important during the heading towards the maturity stages of the rice crop. It usually attacks the uppermost leaf sheath that encloses the panicles and causes rotting of the panicles.

File Courtesy: 
RARS, Karjat
Photo Courtesy: 
Dr. D. Krishnaveni (DRR)
27
Jul

Sheath rot disease

1. Causal organism: Sarocladium oryzae (Sawada) W. Gams & D. Hawksw.

2. The pathogen generally attacks the upper most leaf sheath enclosing the young panicles.

3. Oblong or irregular spots with chocolate brown colour develop on the boot leaf sheath. Sheath rots disease of rice, caused by Sarocladium oryzae.

4. It inflicts damage to the uppermost flagleaf sheath by infecting the sheath covering the young panicles at the booting stage.

File Courtesy: 
RARS, Karjat
Photo Courtesy: 
Dr. D. Krishnaveni (DRR)
27
Jul

Damage symptoms of False Smut disease

1. In one panicle, only few seeds showing the disease symptoms.

2. Individual grains of the panicle are transformed into yellow or greenish velvety spore balls.

3. The spore balls are covered by a membrane in the early stages, which bursts on further growth and the loose velvety pseudomorphs become visible.

File Courtesy: 
RARS, Karjat
Photo Courtesy: 
http://www.flickr.com/photos/cropprotection/5074767888/
27
Jul

Conditions favourable for False Smut disease

1. Low temperature (20°C).
2. High relative humidity (>92%).
3. Moderate rainfall with intermittent clear and drizzling weather during flowering.
4. More prevalent in seasons favorable for good growth and high yields.
5. Host pants: Grasses and Wild rice.

File Courtesy: 
RARS, Karjat
27
Jul

False Smut Disease

Causal organism: Ustilaginoidea virens (Cke.)

Local name:

False smut is a fungal disease and is more severe in the years of high rainfall.

The farmers consider its incidence as an omen of Good Harvest.

Period of occurrence : Panicle emergence .

Extent of yield loss : Negligible, Udupi district 23% and DWR 3%.

• 1000 grain weight by 48%.

• Chaffyness by 40%.

• Seedling growth.

File Courtesy: 
RARS, Karjat
Photo Courtesy: 
Dr. D. Krishnaveni (DRR)
27
Jul

Control Measures for Rice Leaf Scald disease

Cultural practices to control Leaf Scald:

• Use disease free seeds for sowing.

• Do not use high nitrogenous fertilizer.

Chemical control measures for Leaf Scald :

If the disease observed in the field then spray 0.1% Carbendazim solution or 2g mancozeb or 2.25g Zineb in 1liter of water

File Courtesy: 
RARS, Karjat
27
Jul

Damage Symptoms of Leaf Scald disease

1. Lesions of alternating light tan and dark brown starting from leaf tips or edges.

2. Lesions oblong with light brown halos in mature leaves.

3. Individual lesions 1-5 cm long and 0.5-1 cm wide or may almost cover the entire leaf.

4. Continuous enlargement and coalescing of lesions result in blighting of a large part of the leaf blade.

5. The affected areas dry out giving the leaf a scalded appearance.

File Courtesy: 
RARS, Karjat
Photo Courtesy: 
RARS, Karjat
27
Jul

Leaf Scald disease

1. Causal Organism: Monographella albescens.

2. Period of occurrence: The disease is important during the tillering and stem elongation stages of the crop.

3. Extent of yield loss: In India 20-30% yield losses were reported due to this disease.

4. Alternate hosts: The hosts of the fungus include Echinochloa crus-galli (L.) P. Beauv. (cockspur) and Oryza sativa L. (rice).

5. Mode of transmission/ dissemination.

File Courtesy: 
RARS, Karjat
Photo Courtesy: 
RARS, Karjat
27
Jul

Control Measures for Rice Brown leaf spot

Cultural practices to control Brown leaf spot:

1. Use disease free seeds for sowing.

2. Do not use high nitrogenous fertilizer.

3. Use resistant variety Amruth.

Chemical control of Brown leaf spot:

4. If the disease observed in the field than spray 2g mancozeb or 2.25g Zineb in 1liter of water.

File Courtesy: 
RARS, Karjat
27
Jul

Damage symptoms of Brown leaf spot

1. The symptoms of the disease appear on the coleoptile, the leaves, leaf sheath and also the glumes.

2. On the leaves the spots vary in size (1cm) and shape from minute dots to circular, eye shaped or oval spots is seen in the central portion.

3. The seeds are some times shriveled and discolored.

File Courtesy: 
RARS, Karjat
Photo Courtesy: 
RARS, Karjat
27
Jul

Details of Brown leaf spot disease

Period of occurrence: Seedling to maturity.

Extent of yield loss: 50-90% in extreme cases.

Collateral hosts: Digitaria sanguinalis, Leersia hexandra, Echinochloa colona, Pennisetum typhoides, Setariitalica, Cynodon dactylon.

 Favorable conditions for the pathogen:

 • Temperature of 25-30°C .

• Relative humidity (>90%).

• Heavy and late north-east monsoon.

File Courtesy: 
RARS, Karjat
Photo Courtesy: 
Dr. D. Krishnaveni (DRR)
27
Jul

Brown leaf spot

1. Causal organism: Helminthosporium oryzae.

2. Local name:

3. Brown spot is a fungal disease that can infect both seedlings and mature plants. This disease is more severe in areas of poor management.

4. Major cause of 'Bengal Famine' in 1942, due to yield loss of 50-90%, resulting in death of 2 m people.

File Courtesy: 
RARS, Karjat
Photo Courtesy: 
Dr. D. Krishnaveni (DRR)
27
Jul

Damage symptoms of Sheath Blight disease (Parnkarpa)

1. Appearance of one or more relatively large, oblong or irregularly elongated lesions on the leaf sheath; in advanced stages center of the lesion becomes bleached with an irregular purple brown border.

2. Initially these lesions are white in colour later it turns to dark brown.

3. At severe condition drying of leaves.

File Courtesy: 
RARS, Karjat
Photo Courtesy: 
http://www.forestryimages.org
27
Jul

Control of Sheath Blight disease (Parnkarpa)

Cultural Practices to control Sheath Blight disease:

• Avoid using infected seed.

• Apply moderate 'N' levels (80-100 kg/ha) in 3-4 splits.

• Avoid excess 'N', skip final 'N' in sheath blight infected fields.

• Destroy stubbles / weeds, etc.

• Check brown plant hopper population.

Chemical control for Sheath Blight disease:

• Spraying fungicides of 1g carbendazim 50WP (540g/acre) or 2.0g mancozeb 75WP OR 1ml hexaconozole in 1 liter of water.

File Courtesy: 
RARS, Karjat
27
Jul

Details of Sheath Blight disease ( Parnkarpa)

1. Period of occurrence: Tillering to milk stage.

2. Extent of yield loss: On an average, 20 to 50% annual yield loss Alternate hosts: Among the plants recorded as hosts are, sugarcane, bean, soybean, tomato, egg plant, tobacco, water hyacinth , hyacinth bean and green gram.

File Courtesy: 
RARS, Karjat
Photo Courtesy: 
Dr. D. Krishnaveni (DRR)
27
Jul

Sheath Blight disease ( Parnkarpa)

1. Causal organism of Sheath blight: Rhizoctonia solani Kuhn.

2. Marathi name: Parnkarpa

3. Sheath blight is a fungal disease, more common in rainy season than in dry season in the topics.

4. This disease is problematic in areas where irrigation facilities are abundant.

5. Due to blighting of the leaf sheaths, it is commonly called as sheath blight.

File Courtesy: 
RARS, Karjat
Photo Courtesy: 
Dr. D. Krishnaveni (DRR)
27
Jul

Why and when it occurs for Rice blast disease (Karapa)

1. Infection is most likely after long periods of rain or high humidity with little or no wind movement and relatively warm nights (63-73°F or 18-23°C).

2. These conditions favor spore germination and formation. Ensuring that the plants are flooded and avoiding drought stress are effective in controlling the fungus.

File Courtesy: 
RARS, Karjat
27
Jul

Prevention and Treatment for Rice blast disease ( Karapa)

1. Cultural practices to control Rice Blast include the destruction of diseased crop residue, careful use of nitrogen fertilizer (high levels increase the likelihood of disease), the use of water seeding rather than drill seeding and ensuring that plants remain flooded all seem to help control the disease. Planting of resistant varieties of rice may also be helpful.

File Courtesy: 
RARS, Karjat
Photo Courtesy: 
http://www.lookatvietnam.com
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