Best Viewed in Mozilla Firefox, Google Chrome

Diseases

Diseases
31
Jul

Bacterial leaf blight (Xanthomonas oryzae pv. oryzae)

Greenish-yellow strips appear along the leaf margins and extend both lengthwise and breadthwise. The leaf starts drying from the tip, becomes white in severe cases and dries up completely. The disease sometimes attacks the freshly transplanted seedlings which start wilting and in a few days the whole clump dries up. The bacterium perpetuates through seed, rice straw, and roots of non-host plants during the off-season. In order to mitigate the losses, adopt the following measures :

File Courtesy: 
Punjab Agricultural University, Ludhiana
31
Jul

Diseases of Punjab

1. Bacterial leaf blight
2. Bacterial leaf streak
3. Blast
4. Brown leaf spot
5. Sheath blight
6. Sheath rot
7. Stem rot
8. False smut
9. Bunt (also called Kernel Smut

File Courtesy: 
Punjab Agricultural University, Ludhiana
30
Jul

Management of Bacterial Leaf Blight of Rice

No single effective control measure is available. Therefore, integrated measures are suggested.
Use of resistant cultivars
Use of resistant cultivars is the most economic and environment safe strategy for the management of bacterial blight disease. Although several BB R genes have been identified and characterized, the effectiveness of these genes varies due to difference in virulence profile of the pathogen in different geographical regions. In India, a large no. of rice varieties has been released showing resistance /tolerance to bacterial blight.
Chemical Control

File Courtesy: 
CRRI
30
Jul

Predisposing factors for Bacterial Leaf Blight of Rice

  • Lateritic and alluvial soil favour more bacterial blight diseases. 
  • Water logging condition encourages disease development. 
  • Excessive use of N fertilizers from tillering stage to maximum tillering stage encourages disease development. 
  • Growing of the crop under shade favours disease development.
  • Pruning of leaves at the time of transplanting favours disease development.

 

File Courtesy: 
CRRI
30
Jul

Causal organism of Bacterial Leaf Blight of Rice

The causal organism is the bacterium Xanthomonas oryzae pv. oryzae (Ishiyama) Swings et al. According to the new classification system, it has been placed in:
Phylum : Proteobacteria
Class : Gyammaproteobacteria
Order : Xanthomonadales
Family : Xanthomonadaceae

File Courtesy: 
CRRI
30
Jul

Symptoms of Bacterial Leaf Blight of Rice

• Water soaked lesions move from tip downwards on the edges of leaves.

• Gradually symptoms turn into yellow and straw coloured stripes with wavy margins.

• In early morning in humid areas yellowish, opaque, turbid drops of bacterial ooze may be seen.

• In Kresek (wilt) phase, leaves roll completely, droop and plants die completely.

File Courtesy: 
CRRI
Photo Courtesy: 
CRRI
30
Jul

Economic Importance of Bacterial Leaf Blight of Rice

1. The extent of yield loss depends on the growth stages of the crop at which it is infected, the level of susceptiblility of the cultivar, season, climatic condition and level of nitrogen fretilizer applied.

2. The damage may be due to partial or total blighting of the leaves or complete wilting of the affected tillers leading to unfilled grains.

File Courtesy: 
CRRI
30
Jul

History, occurrence and distribution of Bacterial Leaf Blight of Rice

1. Bacterial leaf blight of rice caused by Xoo is one of the most destructive diseases of rice in majority of the rice growing countries especially in Asia.

2. Though the disease has been known in Japan since 1884, its bacterial nature was established in 1922. Subsequently the disease was reported from most of the rice growing countries.

File Courtesy: 
CRRI
30
Jul

Bacterial Leaf Blight of Rice

File Courtesy: 
CRRI
Photo Courtesy: 
CRRI
30
Jul

Management options of Bacterial Leaf Streak of Rice

i. Varietal Resistance
Grow resistant varieties like Bala, Padma, Sabarmati and moderately resistant varieties like Krishna, Jamuna etc. Use certified seeds from the reliable sources.
ii. Cultural practices
 The disease can be controlled by proper application of fertilizers and proper planting spacing.
 Practicing field sanitation is important. Ratoons, straws and volunteer seedlings left after harvest can be destroyed to minimize the initial inoculum at the beginning of the season. Providing good drainage system especially in seedbeds can also manage this disease.

File Courtesy: 
CRRI
30
Jul

Host range of Bacterial Leaf Streak of Rice

Species of wild rice such as Oryza spontanea, O. perennis balunga, O. nivara, O. breviligulata, O. glaberrima, and Leersia hexandra Sw. (southern cutgrass) are alternate hosts of the disease.

File Courtesy: 
CRRI
30
Jul

Causal Organism and Predisposing factors for Bacterial Leaf Streak of Rice

The bacteria causing the disease X. oryzae pv.oryzicola occur as rods. They are 1.2 x 0.3-0.5 µm in dimension. They are single, occasionally in pairs but not in chains. The bacteria have no spores and no capsules. They move with the aid of a single polar flagellum. They are Gram-negative and aerobic and can grow favourably at 28 °C.
The bacterial colonies on nutrient agar are pale yellow, circular, smooth, convex, and viscid and have an entire margin. Their growth on slant is filiform. Growth in nutrient broth is moderate with a surface ring growth without a definite pellicle.

File Courtesy: 
CRRI
30
Jul

Symptoms of Bacterial Leaf Streak of Rice

File Courtesy: 
CRRI
Photo Courtesy: 
http://www.sciencephotolibrary.com/images/download_lo_res.html?id=670017710
30
Jul

Economic importance of Bacterial Leaf Streak of Rice

1. Under favourable weather conditions particularly typhoons and rain storms, the disease spread through entire fields, all the upper leaves become infected and turn brown resulting in heavy damage.
2. Losses as high as 32.3% in 1000-grain weight due to BLS were reported. At three disease intensities, the estimated yield losses were 8.3%, 13.5%, and 17.1% in the wet season and 1.5%, 5.9%, and 2.5% during the dry season.

File Courtesy: 
CRRI
30
Jul

History, distribution and occurrence of Bacterial Leaf Streak of Rice

1. The disease was first described as stripe disease by Reinking in 1918 from the Philippines. Identification and description of the causal organism was given by Fang et al from China in 1957.
2. In India, it was first reported by Srivastava et al (1967) who noticed its occurrence in U.P, Madhya Pradesh, Maharashtra and Bihar.
3. Shekhawat and Srivastav (1971, 1972) Chattopadhyaya and Mukharji (1968) observed it in Mysore, Haryana, Andhra Pradesh, West Bengal and Orissa.

File Courtesy: 
CRRI
30
Jul

Bacterial Leaf Streak of Rice

1. Bacterial Leaf Streak (BLS) initited by Xanthomonas oryzae pv. Oryzicola is important bacterial disease next to preventing the realisation of high yielding potential offered by intensive cultivation.
2. Though it is less devastating than Blb, it causes substantial yield losses and is a major constraint in production.

File Courtesy: 
CRRI
29
Jul

Management of False Smut of Rice

- Use of recommended doses of fertilizer.

- Deep ploughing in summer stubbles.

- Avoid flow of irrigation water from infected fields to healthy fields.

- Chemical spray: 2 spray of 0.1% Propiconazole (Tilt) solution (1 gm/lt water).

First spray before panicle emergence and second spray 10 days just after panicle emergence.

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

False Smut of Rice

 

Symptoms: The fungus transforms individual grains into greenish spore balls of velvetty appearance.

Due to the development of the fructification of the pathogen, the ovaries are transformed into large velvetty green masses. Usually only a few spikelets in a panicle are affected.

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 Bacterial Leaf Blight (BLB) of Rice

- Burn the stubbles. - Use optimum dose of fertilizers

. - Avoid clipping of tip of seedling at the time of transplanting.

- Avoid flooded conditions.

- Remove weed hosts.

- Grow resistant cultivars like Birsamati, Birsa Vikas Dhan 110, Birsa Vikas Dhan 109, Hazaridhan, Sadabahar, Birsa Dhan 108, Shivam and Swarna showed resistance against bacterial leaf blight (BLB) of Rice.

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

- Foliar spray: Make solution of 2 gm Streptocycline in 10 lt water (0.02%).

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

Pathogen of Bacterial Leaf Blight (BLB) of Rice

1. The bacterium Xanthomonas oryzae pv. Oryzae is strict aerobe, gram negative, non spore forming, rod shaped with size ranging from 1-2 x 0.8-1.0um with monotrichous polar flagellum of 6-8 um. The bacterial cells are capsulated and are joined to form an aggregate mass. Colonies are circular, convex with entire margins, whitish yellow to straw yellow later and opaque.

File Courtesy: 
C S Azad University of Agriculture and Technology, Kanpur
Syndicate content
Copy rights | Disclaimer | RKMP Policies