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Rice Blast

Rice Blast
1
Nov

Blast

Blast

Casual Organism : Pyricularia Grisera

Symptoms:

The leaves show spindle shaped spots with grey centre and dark brown margin.  

The lesions enlarge and cause drying of leaves. The nodes and neck regions turn black and cause rotting and breaking with complete/partial chaffiness of earhead.

File Courtesy: 
DRD, Patna
Photo Courtesy: 
Dr.Krishnaveni DRR
6
Aug

Rice blast

Local name: Causal organism: magnaporthe grisea

1. This diseases affects the crop at all the crop stages viz., nursery, tillering and flowering. The yield loss ranges from 36-50 % depending upon the variety and environment condition.

2. Typical leaf lesion are spindle shaped, usually with redish yellow margin; grey in the centre.

File Courtesy: 
IGKV,Raipur
4
Aug

Rice blast

File Courtesy: 
ICAR NEH, Umiam
Photo Courtesy: 
Dr.Krishna Veni (DRR)
4
Aug

Rice blast

2
Aug

Rice blast

File Courtesy: 
ICAR NEH, Umiam
Photo Courtesy: 
Dr.Krishna Veni (DRR)
2
Aug

Blast (Pyricularia grisea)

 

1. The fungus causes spindle shaped spots with grayish centre and brown margin on the leaves at maximum tillering.

2. It also causes brown lesions on the neck of the panicle showing neck rot symptoms and the panicles fall over.

3. The disease is more severe on Basmati particularly in the submontaneous areas and under application of heavy nitrogenous fertilizers.

File Courtesy: 
Punjab Agricultural University, Ludhiana
Photo Courtesy: 
Dr. D. Krishnaveni (DRR)
1
Aug

Management of blast disease

A) Chemical control
1. Seeds should be soaked for 12 hrs in 0.1 % Carbendazim 50 WP (Bavistin, Derosol or JKstein) prior to sowing of nursery or broadcasting for upland rice.
2. Root dip treatment to the seedlings immediately after uprooting is recommended for 12 hrs in 0.1 % Carbendazim 50 WP (Bavistin, Derosol or JKstein) in low land crop.

File Courtesy: 
Rice Research Station, Kaul (Kaithal), Haryana
1
Aug

Symptoms of blast disease

1. Typical leaf lesions are spindle shaped, usually with reddish yellow margin; grey in the centre.
2. Leaves of susceptible varieties may be killed. The fungus may also attack the stems at nodes which turn dark brown to blackish in colour and tend to break easily.
3. Lesions may also occur on panicle neck. The infected necks turn blackish and break over. Neck blast results in few or no seeds in the panicle.

File Courtesy: 
Rice Research Station, Kaul (Kaithal), Haryana
Photo Courtesy: 
Rice Research Station, Kaul (Kaithal), Haryana
1
Aug

Blast disease

1. Causal organism -Magnaportha grisea is endemic in north eastern states.
2. This disease affects the crop at all the growth stages viz., nursery, tillering and flowering.
3. The yield loss ranges from 36 -50% depending upon the variety and environmental conditions

File Courtesy: 
Rice Research Station, Kaul (Kaithal), Haryana
29
Jul

Management of Rice Blast

- Remove and destory the weed hosts in the field bunds and channels.

- Seed Treatment: with Carbendazim 50 WP or Beam (Tricyclazole) @ 2 gm/kg seed.

- Seed treatment with biocontrol agent: Trichoderma viride@ 4g/kg or Pseudomonas fluorescens @ 10g/kg of seed.

- Avoid close spacing of seedlings in the main field.

- Spray the nursery with Carbendazim 25 g or Edifenphos 25 ml for 8 cent nursery.

- Spray 0.1% solution of Carbendazim 50 WP (@ 1 gm/lt water) or 0.06% Beam (Tricyclazole) (6 gm/10 lt water).

File Courtesy: 
C S Azad University of Agriculture and Technology, Kanpur
29
Jul

Forecasting of Rice Blast

1. Forecasting blast of rice can be made on the basis of minimum night temperature range of 20-260C in association with a high relative humidity range of 90 per cent and above lasting for a period of a week or more during any of the three susceptible phases of crop growth, viz., seedling stage, post transplanting tillering stage and neck emergence stage.

2. In Japan, the first leaf blast model was developed and named as BLAST. Later based on different field experiments various models were developed namely, PYRICULARIA, PYRIVIEW, BLASTAM, EPIBLA and P BLAST.

File Courtesy: 
C S Azad University of Agriculture and Technology, Kanpur
29
Jul

Forecasting of Rice Blast

1. Forecasting blast of rice can be made on the basis of minimum night temperature range of 20-260C in association with a high relative humidity range of 90 per cent and above lasting for a period of a week or more during any of the three susceptible phases of crop growth, viz., seedling stage, post transplanting tillering stage and neck emergence stage.

2. In Japan, the first leaf blast model was developed and named as BLAST. Later based on different field experiments various models were developed namely, PYRICULARIA, PYRIVIEW, BLASTAM, EPIBLA and P BLAST.

File Courtesy: 
C S Azad University of Agriculture and Technology, Kanpur
29
Jul

Favourable Conditions, Mode of Spread and Survival of Rice Blast

Favourable Conditions : Application of excessive doses of nitrogenous fertilizers, intermittent drizzles, cloudy weather, high relative humidity (93-99 per cent), low night temperature (between 15-20OC or less than 26OC), more number of rainy days, longer duration of dew, cloudy weather, slow wind movement and availability of collateral hosts.

Mode of Spread and Survival : The disease spreads primarily through airborne conidia since spores of the fungus present throughout the year.

File Courtesy: 
C S Azad University of Agriculture and Technology, Kanpur
29
Jul

Rice Blast Pathogen

1. Pyricularia oryzae (Syn : P. grisea) (Sexual stage : Magnaporthe grisea).

2. Mycelium of the fungus, is hyaline to olivaceous, septate and highly branched.

3. Conidia are produced in clusters on long septate, olivaceous slender conidiophores.

4. Conidia are obpyriform to ellipsoid, attached at the broader base by a hilum. Conidia are hyaline to pale olive green, usually 3 celled.

5. The perfect state of the fungus is M. grisea. It produces perithecia. The ascospores are hyaline, fusiform, 4 celled and slightly curved.

File Courtesy: 
C S Azad University of Agriculture and Technology, Kanpur
29
Jul

Rice Blast Pathogen

1. Pyricularia oryzae (Syn : P. grisea) (Sexual stage : Magnaporthe grisea).

2. Mycelium of the fungus, is hyaline to olivaceous, septate and highly branched.

3. Conidia are produced in clusters on long septate, olivaceous slender conidiophores.

4. Conidia are obpyriform to ellipsoid, attached at the broader base by a hilum. Conidia are hyaline to pale olive green, usually 3 celled.

5. The perfect state of the fungus is M. grisea. It produces perithecia. The ascospores are hyaline, fusiform, 4 celled and slightly curved.

File Courtesy: 
C S Azad University of Agriculture and Technology, Kanpur
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
27
Jul

Symptoms of Rice blast disease (Karapa)

1. The disease is first seen as elliptical gray-white lesions with reddish edges on the leaves (leaf blast) and stems of the plant.

2. The lesions run parallel to the long axis of the leaf or stem.

3. Most damage occurs when the fungus spreads to the area below the seed head of the plant, causing it to break off (rotten neck).

File Courtesy: 
RARS, Karjat
27
Jul

Rice blast disease (Karapa)

1. Causing organism of Rice blast: Pyricularia oryzae.

2. Marathi name: Karapa.

3. P. oryzae is an ascomycete fungus, a member of the sac fungi.

4. One of the features of these fungi is that they generate spores, called conidia or conidiospores, that can be easily dispersed by the wind and splashing rain.

File Courtesy: 
RARS, Karjat
Photo Courtesy: 
RARS, Karjat
18
Jul

Control Measures of Rice Blast disease in Karnataka

Host plant resistance to Rice Blast disease: Planting resistant varieties is the least expense and safest method of disease control. Rice varieties like Rasi, IET 1791, BR-2655 are some of the blast resistant lines being recommended in Southern dry zone of Karnataka. Varietal mixtures can also be used to reduce slow disease spread.

File Courtesy: 
ZARS, Mandya
Photo Courtesy: 
ZARS, Mandya
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