Best Viewed in Mozilla Firefox, Google Chrome

Crop Protection

Crop Protection
27
Jun

Economic Importance and Symptoms of Leaf Scald

The economic importance of leaf scald disease: 

1. In India and Bangladesh, yield losses of 23.4% and 20-30% were reported respectively.

2. This disease has caused considerable losses in Latin America and West Africa.

The Leaf scald disease symptoms: 

1. Zonate lesions beginning at the leaf tip or margin has alternating bands of tan to gray with reddish brown forming a chevron pattern on the affected leaves. 

File Courtesy: 
http://www.knowledgebank.irri.org
27
Jun

Causal Organism, History, Distribution and Occurence of Leaf Scald

Causal Organism for leaf scald disease is Microdochium oryzae

History

  • In Andhra Pradesh the leaf scald disease was observed in 1981 in the Regional Agricultural Rice Research Station, Nellore.

Distribution and Occurance

1. The Leaf scald disease was observed in USA and West Africa.

2. Leaf scald appears to be very common in Latin America and in other parts of Asia

File Courtesy: 
http://www.knowledgebank.irri.org
27
Jun

Introduction to Leaf Scald (Microdochium oryzae)

 

1.The leaf scald disease has been reported worldwide in rice-growing regions (Farr et al. 2008) and seeds prove as the most important inoculum source.

2. The teleomorph stage, Monographella albescens V.O. Parkinson, Sivan. & C. Booth was recently reported in green and senescent leaves of rice crops close to ripening.

 

File Courtesy: 
http://www.publish.csiro.au/?act=view_file&file_id=DN08030.pdf
25
Jun

Stem Rot (Sclerotium oryzae)

Introduction to 

Stem Rot (Sclerotium oryzae)

1. Stem rot is caused by Sclerotium oryzae, which survive through pin-head size sclerotia in rice straw and the soil. 

2. It is an important disease particularly in water-logged areas. 

3. The sclerotia produced by the fungus serve as primary inoculum source by floating on the water and infecting rice stems of the healthy plant at the waterline.

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

Host plant resistance of Sheath blight

Host plant resistance of Sheath blight: 

Donors 

  • T 141
  • OS 4
  • Saibham
  • BCP 3
  • Saduwee
  • Bhujan
  • Remadja
  • Laka
  • Nangmons 4
  • Ta-Oo-Cho-Z
  • ARC 15368
  • Athebu Phourei  

 

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

Chemical control of Sheath blight

Chemical control of Sheath blight: 

A Spray of either validamycin 3 L @ 2.5 ml or 

  • Hexaconazole 5 EC @ 2.0 ml or
  • Thifluzamide 24 SC @ 0.75 ml or
  • Propiconazole 25 EC @ 1 ml or 
  • Thiophanate-methyl 70 WP or 
  • Carbendazim 50 WP @ 1.0 g / L of water will prevent the spread of the disease. 

 

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

Cultural practices to control Sheath Blight

Cultural practices for the control of Sheath Blight are: 

1. Closer plant spacing should be avoided; otherwise it develops a dense crop growth favorable for the horizontal spread of the disease.

2. Need-based or real-time or split application of nitrogen fertilizer is recommended in the fields with a high amount of inoculum.

3. Sanitation, specifically removing of weeds, help to control sheath blight because the pathogen also attacks weeds which are commonly found in rice fields. 

 

File Courtesy: 
http://www.knowledgebank.irri.org/ricedoctor/index.php?option=com_content&view=article&id=565&Itemid=2770
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)
Syndicate content
Copy rights | Disclaimer | RKMP Policies