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Diseases

Diseases
29
Jul

Bacterial Leaf Blight (BLB) of Rice

 

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

Management of Sheath Blight of Rice

- Avoid excess doses of fertilizers.
- Adopt optimum spacing.
- Eliminate weed hosts.
- Apply organic amendments.
- Avoid flow of irrigation water from infected fields to healthy fields.
- Deep ploughing in summer and burning of stubbles.
- Seed Treatment: with Carbendazim 50 WP or Beam (Tricyclazole) @ 2 gm/kg seed.

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

Pathogen of Sheath Blight of Rice

Rhizoctonia solani (Sexual stage : Thanetophorus cucumeris).

The fungus produces usually long cells of septate mycelium which are hyaline when young, yellowish brown when old. It produces large number of globoses sclerotia, which are initially white, later turn to brown or purplish brown.

Mode of spread and survival of Sheath Blight of Rice: The pathogen can survive as sclerotia or mycelium in dry soil for about 20 months but for 5-8 months in moist soil. It infects more than 188 crop species in 32 families. Sclerotia spread through irrigation water.

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

Sheath Blight of Rice

 

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

Mode of Spread and Survival of Brown Leaf Spot of Rice

1. The infected seeds are the most common source of primary infection. The conidia present on infected grain and mycelium in the infected tissue may viable for 2 to 3 years.

2. The fungus may survive in the soil for 28 months at 30OC and 5 months at 35OC. Airborne conidia infect the plants both in nursery and in main field.

3. Maximum flight of conidia take place at a wind velocity of 4.0 - 8.8 hr. Minimum temperature of 27 -28OC, Relative humidity of 90-99% and rainfall of 0.4 -14.4 mm favored the dispersal of the conidia to maximum extent.

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

Pathogen of Brown Leaf Spot of Rice

Helminthosporium oryzae (Syn : Drechslera oryzae) (Sexual stage : Cochliobolus miyabeanus).

1. H. oryzae produces greyish-brown to dark brown septate mycelium. Conidiophores may arise singly or in small groups.

2. They are straight, sometime geniculate, pale to brown in colour.

3. Conidia are usually curved with a bulge in the centre and tapering towards the ends occasionally almost straight, pale olive green to golden brown colour and are 6-14 septate.

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

Brown Leaf Spot of Rice

 

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

Rice Diseases of Uttar Pradesh State

Rice crop of different regions within Utter Pradesh state is attacked by five major diseases. They are-
1. Rice Blast
2. Brown Leaf Spot of Rice
3. Sheath Blight of Rice
4. Bacterial Leaf Blight (BLB) of Rice
5. False Smut of Rice

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

Symptoms of Bacterial Leaf Streak disease

 

1. Bacterial Leaf Streak first appears as short, water-soaked streaks between the veins, which become longer and translucent and turn to light brown or yellowish brown.

2. Large areas of the leaf may become dry due to numerous streaks. At the later stage the disease is indistinguishable from the bacterial leaf blight.

File Courtesy: 
RARS, Karjat
Photo Courtesy: 
http://www.fao.org/DOCREP/006/Y4011E/y4011e0x.htm
27
Jul

Bacterial Leaf Streak (BLS) of rice

 

1. Causal Organism : Xanthomonas oryzae pv. oryzicola.

  2. Bacterial Leaf Streak The disease is usually observed during the tillering stage of the rice crop.

3. The rice plant can easily recover at the later growth stages and grain yield losses are minimal.

4. Losses as high as 32.3% in 1000-grain weight due to BLS were reported.

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

Management of Bacterial Leaf Blight disease

 

1. Use seed from disease free crop.

2. Treat the seeds by soaking it for 12hrs in a mixed solution of streptocycline(0.15%) and wetable Ceresan (0.05%) followed by hot water treatment at 52oC-54oC foe 30 minutes.

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

Management of Bacterial Leaf Blight disease

 

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

Symptoms of Bacterial Leaf Blight disease

1. The bacterium induces either wilting of plants or leaf blight. Wilting syndrome known as 'Kresek' occurs sporadically in the fields causing serious damage.

2. Bacterial leaf blight commonly occurs within 3-4 weeks after transplantation of the crop. Kresek results either in the death of whole plants or wilting of only a few leaves.

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

Bacterial Leaf Blight disease

1. Causal Organism: Xanthomonas compestris pv. Oryzae.

2. Bacterial blight is a monsoon disease and its incidence and severity is very much influenced by rainfall, number of rainy days, and susceptibility of the cultivar and nitrogen fertilizer application.

3. Severe epidemics recorded in 1979 and 1980 in northwestern India, reducing the grain yields drastically.

File Courtesy: 
RARS, Karjat
Photo Courtesy: 
RARS, Karjat
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