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Diseases

Diseases
25
Jun

Biological control of Sheath Blight

The biological control for Sheath Blight: 

1. Antagonistic micro-organisms – Fluorescent bacteria were isolated that showed high level of antagonism against sheath blight pathogens. 

2. Pre-inoculation of rice with R. oryzae isolates, to considerably reduce the severity of sheath blight caused by R. solani.

3.  In Rajshahi (Bangladesh), press-mud, sawdust and rice bran reduced disease severity.

 

File Courtesy: 
http://www.fao.org/teca/content/validation-and-promotion-technologies-rice-she ath-blight-management
25
Jun

Alternate Host and Management Options of Sheath Blight

Alternate host of Sheath Blight

1. The pathogen has a wide host range and occurs on all grasses and broad leaved weeds grown on rice bunds produces similar symptoms and producing sclerotial bodies.

2. These sclerotial bodies fall in paddy water and initiate infection on rice crop. 

Management options of Sheath Blight: 

Sheath Blight management options include;

  • Cultural,
  • Biological,
  • Chemical and
  • Use of resistant varieties.

 

File Courtesy: 
DRR training manual (Dr. krishnaveni)
25
Jun

Predisposing factors of Sheath Blight

 Predisposing factors of Sheath Blight: 

1. Relative humidity and temperature are the critical factors for sheath blight infection. 

2. The pathogen thrives when the humidity is around 96 % in the crop canopy. 

3. High infection occurs at 100 % relative humidity and gradually falls when it is decreased. 

4. High temperature (28 – 320C) and frequent rainfall favors disease development. 

 

File Courtesy: 
DRR training manual (Dr. krishnaveni)
25
Jun

Causal Organism of Sheath Blight and Plant parts affected by Sheath Blight

Causal Organism of Sheath blight

Sheath blight disease is caused by the fungus Thanetophorus cucumeris anamorph (Rhizoctonia solani

Plants parts effected by Sheath Blight

1. Pathogen incites develops the disease inside just above the water-line in rice fields, the pathogen affects all plant parts viz., sheaths, inter node, upper leaves and panicles.

File Courtesy: 
DRR training manual (Dr. krishnaveni)
Photo Courtesy: 
CRRI
25
Jun

Symptoms of Sheath blight

The symptoms of Sheath blight disease are: 

1. Sheath blight disease usually appears in the later growth stages of the plant.

2. Initial symptoms usually develop as lesions on sheaths of lower leaves near the water line when plants are in the late tillering or early internode elongation stage (approximately 10 – 15 days after flooding) varies from place to place. 

File Courtesy: 
epidemiology of rice diseases (Dr. krishanveni)
Photo Courtesy: 
epidemiology of rice diseases (Dr. krishanveni)
25
Jun

Economic importance of Sheath blight

 Economic Importance of Sheath Blight: 

 1. Rice sheath blight is an increasing concern for rice production especially in intensified production systems. 

2. In Japan, the disease caused a yield loss of as high as 20% and affected about 120,000-190,000 hectares. 

3. A yield loss of 25% was reported if the flag leaves are infected. 

File Courtesy: 
http://www.knowledgebank.irri.org/ricedoctor/index.php?option=com_content&view=article&Id=565&Itemid=2770
Photo Courtesy: 
CRRI
25
Jun

Distribution and occurrence of Sheath Blight

The disease sheath blight  appeared in moderate to severe intensity in a few states like 

 

  • Andhra Pradesh, 
  • Kerala, 
  • Orissa and 
  • West Bengal

 

File Courtesy: 
DRR training manual Dr. krishnaveni)
25
Jun

Introduction to Sheath Blight Thanatephorus cucumeris

Introduction to Sheath Blight  Thanatephorus cucumeri

 

1. Incidence of Sheath blight of rice caused by Rhizoctonia solani Kühn , has become more prevalent on many improved varieties currently grown in India. 

2. The disease generally appears at the maximum tillering stage and affects all plant parts above water-line, viz. sheaths, internodes, upper leaves and panicles.

File Courtesy: 
DRR training manual Dr. krishnaveni)
Photo Courtesy: 
CRRI
25
Jun

Chemical control of Bacterial leaf blight

 

Chemical control for Bacterial Leaf Blight: 

 

1. Copper fungicides containing 50% copper oxychloride have been found to be quite effective.  

2. Agrimycin-100 has also been reported to be effective against bacterial blight.

3. Synthetic organic bactericides such as nickel dimethyl dithiocarbamate, dithionone, phenazine are also effective against this disease.

 

 

 

File Courtesy: 
Rice Nanda Book
25
Jun

Biological control of Bacterial Leaf Blight

Biological control of Bacterial Leaf Blight: 

1. The deployment of bio-control agents at the seedling stage may prevent early infection, resulting in considerable reduction of disease indication.

2. However, a systematic search for bio-control agents that would bring about significant bacterial blight suppression in field conditions is necessary for establishment of biological control.

 

File Courtesy: 
http://www.dawn.com/2007/11/05/ebr5.html
25
Jun

Cultural practices to control Bacterial leaf blight

 

Cultural practices for control of Bacterial Leaf Blight: 

1. Secure disease free seed

2. Balanced fertilization, avoid excess N application Skip N application at booting ( if disease is moderate)

3. Drain the field (except at flowering stage of the crop)

4. Destruction of wild collateral hosts

5. Avoid flow of water from affected fields

6. Insect pest control as they may serve as the carrier of the bacteria

 

File Courtesy: 
Dr. Krishnaveni rice diseases (PPT)
25
Jun

Management Options of Bacterial leaf blight

 

Management Options of Bacterial leaf blight: 

 

  • Management options include cultural, chemical and biological control.
File Courtesy: 
ADVANCES IN INTEGRATED RICE DISEASE MANAGEMENT ( Dr. krishnaveni)
Photo Courtesy: 
CRRI
25
Jun

Varietal resistance of Bacterial Leaf Blight

 

File Courtesy: 
ADVANCES IN INTEGRATED RICE DISEASE MANAGEMENT ( Dr. krishnaveni)
25
Jun

Alternate Host of Bacterial Leaf Blight

 

Alternate Host  of  Bacterial Leaf Blight: 

1. Alternate host for bacterial blight is the common weeds in rice fields such as Echinochloa colona and
Brachiaria mutica.
 
2. These diseased weeds harbor the inoculum during the off season. 
 
File Courtesy: 
ADVANCES IN INTEGRATED RICE DISEASE MANAGEMENT ( Dr. krishnaveni)
25
Jun

Predisposing factors of Bacterial Leaf Blight

Predisposing factors of Bacterial Leaf Blight

 

1.Predisposing factors for bacterial leaf blight are :

  • Excessive vegetative growth predisposes susceptible plants to attack by the sheath blight organism. 

2. The development and severity of the disease increases with the increase in the age of host plant. 

3. Both vertical and horizontal development of the disease was the highest at flowering stage in majority of the rice cultivars. 

File Courtesy: 
ADVANCES IN INTEGRATED RICE DISEASE MANAGEMENT ( Dr. krishnaveni)
25
Jun

Causal Organism of Bacterial Leaf Blight

 

Causal Organism  of  Bacterial Leaf Blight
 
  • Bacterial blight caused by Xanthomonas campestris pv. oryzae,

 

 

File Courtesy: 
ADVANCES IN INTEGRATED RICE DISEASE MANAGEMENT ( Dr. krishnaveni)
25
Jun

Symptoms of Bacterial Leaf Blight

Symptoms of BLB:

 

1. Bacterial leaf blight is a typical vascular disease and has three distinct phases of symptoms. viz., leaf blight phase, kresek phase and pale yellow leaf phase.  

File Courtesy: 
DRR Training Manual
Photo Courtesy: 
Rice Blast Disease and its Management ( Dr . Krishnaveni)
25
Jun

Economic importance of Bacterial Leaf Blight

Economic Importance of BLB:

1. The intensity of the disease is more where rice is grown under high Nitrogen fertilizer input condition. 
 

2. The yield loss due to this disease is more than 50%.

File Courtesy: 
http://www.knowledgebank.irri.org/ricedoctor/index.php?option=com_content&view=article&id=553&Itemid=2758
Photo Courtesy: 
Rice Blast Disease and its Management ( Dr . Krishnaveni)
25
Jun

Distribution and occurrence of Bacterial Leaf Blight

 
1. Bacterial leaf blight is one of the most destructive diseases of rice in India especially in the irrigated and rainfed lowland ecosystems.
 
 

2. The kresek phase of disease is more common and often occurs in epidemic form in Punjab, Haryana, and western Uttar Pradesh, and occasionally in Bihar.

File Courtesy: 
ADVANCES IN INTEGRATED RICE DISEASE MANAGEMENT ( Dr. krishnaveni)
25
Jun

History of Bacterial Leaf Blight

1. Severe epidemics were recorded in 1979 and 1980 in north western India, reducing the grain yields drastically. 

2. In Punjab and Haryana states of India, major epidemics occurred in 1979 and 1980; severe kresek was observed resulting in total crop failure (POS 1979 &1980).  

3. The disease was later reported in epidemic form during 1998 in Palakad district of Kerala and since then it has become endemic in that region (Priyadarishini and Gnanamanickam, 1998).

 

File Courtesy: 
ADVANCES IN INTEGRATED RICE DISEASE MANAGEMENT ( Dr. krishnaveni)
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