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Diseases

Diseases
7
Jul

Causal Organism and Symptoms of Downy Mildew

Causal organism of Downy Mildew

The causal organism for Rice Downy mildew disease is Sclerophthora macrospora.

Symptoms of Rice Downy Mildew disease:

1. Downy mildew infection begins as angular yellow spots on the upper leaf surface.

2. Then they turn brilliant-yellow colored spots.

3. Eventually, the internal parts of these spots become brown with yellow margins.

File Courtesy: 
http://www.oisat.org/pests/diseases/f ungal/downy_mildew.html
Photo Courtesy: 
http://www.hort.wisc.edu/HortClub/Plant%20Pathology%20Project/downy_mildew.htm
7
Jul

Introduction and Pre-disposing factors of Downy Mildew

Introduction to Downy Mildew:

1. Rice Downy mildew disease has been reported as one of the most important disease in most of the Rice producing countries in the world.

2. The causal fungus, Scleropthora macrospora. Infects rice plants systematically except root system and causes stunting of the whole plants and mosaic or yellowing of leaves.

3. It has a wide host range in graminaceous plants including wheat, barley, corn, sorghum and various pasture and weed grasses.

7
Jul

Causal Organism and Symptoms of Crown Sheath Rot

Causal organism of Crown Sheath Rot

The causal organism for Crown sheath rot disease is "Gaeumannomyces graminis".

Symptoms of Crown Sheath Rot

The symptoms of Crown Sheath Rot are:

1. Black to brown diffuse lesions on the sheath near the water line, perithecia necks protruding from the upper surface with a thick fungal mat between the leaf sheath and culm.

File Courtesy: 
http://www.lsuagcenter.com/NR/rdonlyres/B27 31525-EFA1-4336-8640-5FF16D8470B4/58936 /RiceDiseaseIDphotolink.pdf
Photo Courtesy: 
http://www.forestryimages.org/browse/detail.cfm?imgnum=5390498
7
Jul

Pre-disposing factors and Management Options of Crown Sheath Rot

Predisposing Factors of Crown Sheath Rot

Factors favour the development of Crown sheath rot disease are application of excess nitrogen.

Management options of Crown Sheath Rot:

Crown sheath rot disease management options include cultural practices. Cultural practices of Crown Sheath Rot

Cultural practices for the control of Crown Sheath Rot:

1. Crop rotation with non-grass crops.

7
Jul

Crown Sheath Rot Introduction, Distribution and Occurance

Introduction to Crown Sheath Rot

1. It is also called as Black Sheath Rot.

2. The causal organism for Crown sheath rot disease is "Gaeumannomyces graminis".

3. Black sheath rot or crown rot was considered a minor disease of rice in Texas for several decades, but has become important when intensive infection reported systems.

Distribution and occurrence of Crown Sheath Rot:

The distribution Crown sheath rot is found throughout Louisiana especially severe where excess nitrogen was applied.

File Courtesy: 
http://www.lsuagcenter.com/NR/rdonlyr es/B2731525-EFA1-4336-8640-5FF16D8 470B4/58936/RiceDiseaseIDphotolink.pdf
7
Jul

Symptoms and Causal Organism of Black Kernel

Symptoms of Black kernel:

1. Glumes are discolored.

2. In severe infection, the rice kernel shows black discoloration.

Causal Organism of Black kernel

1. Causal organism of Black kernel disease is Curvularia Boedijn.

7
Jul

Black Kernel Introduction, History and Economic Importance

Introduction to Black kernel

  • Several species of Curvularia are found on rice grains causing discoloration, and a few of them mould the grain and may even cause leaf spots under certain conditions.
  • It is a minor disease.
  • Black kernel disease infected glumes are discolored.

History of Black kernel

File Courtesy: 
http://www.knowledgebank.irri.org/smta/ind ex.php?option=com_content&view=article& id=271&catid=35&Itemid=84
7
Jul

Cultural practices for control of Aggregate sheath spot:

Cultural practices for control of Aggregate sheath spot:

1. Burning of crop residues after harvest provides the most effective control for this disease.

2. Complete removal of infected crop residues also minimizes carryover of the inoculum.

3. Moldboard ploughing, crop rotation, or fallowing also minimizes carryover inoculum.

4. Avoid dense rice stands as they may enhance disease development.

File Courtesy: 
http://www.ipm.ucdavis.edu/PMG/r682100311.html
7
Jul

Symptoms, Causal Organism and Pre-disposing factors of Aggregate Sheath Spot

Symptoms of Aggregate sheath spot

1. Aggregate sheath spot lesions appear on the lower leaf sheaths at the water line during the tillering stage.

2. Lesions are circular to elliptical with gray-green to straw-colored centers surrounded by distinct brown margins.

3. Frequently, additional margins are formed around the initial lesion thus producing a series of concentric bands.

4. A strip of light-colored necrotic cells runs down the lesion center.

File Courtesy: 
http://www.ipm.ucdavis.edu/PMG/r682100311.html
7
Jul

Aggregate sheath spot introduction, distribution and occurance

Introduction to Aggregate sheath spot 

1. Aggregate sheath spot produce lesions, which are circular to elliptical with gray-green to straw-colored centers surrounded by distinct brown margins.

2. Aggregate sheath spot is caused by the fungus Rhizoctonia Oryzae-sative

3. The fungus produces glabose sclerotia on the surface of infected rice leaf sheath as well as cylindrical selerotia inside the cell of infested tissue.

File Courtesy: 
http://cecolusa.ucdavis.edu/files/54685.pdf
Photo Courtesy: 
http://www.ipmimages.org/browse/detail.cfm?imgnum=5390466
7
Jul

Management Options for control of Udbatta Disease

Udbatta disease management options include

  • cultural practices,
  • chemical control and

Cultural practices of Udbatta disease

  • Use disease free seeds for sowing. Hot water seed treatment at 540C for 10 minutes.
  • Removal and destruction of diseased panicles in field.

Chemicals for the control of Udbatta disease.

File Courtesy: 
www.new.dli.ernet.in
7
Jul

Pre-disposing factors and Alternate Host of Udbatta disease

Predisposing factors of Udbatta disease

High soil temperature (280C) and abundant soil moisture in the nursery bed during the first week of sowing and in subsequent stages are conducive for the disease.

Alternate host of Udbatta disease

The fungus survives on several grass hosts, including Isachne elegans, Eragrostis teneefolia, Arthraxon ciliaris, Saccolepsis indica, Cynodon doctylon, Pennisetum sp and rye grass.

Disease cycle of Udbatta disease

File Courtesy: 
DRR Tarining Manual
7
Jul

Symptoms and Causal Organism of Udbatta disease

Symptoms Udbatta disease

File Courtesy: 
DRR Tarining Manual
Photo Courtesy: 
CRRI
7
Jul

Introduction, Histroy, Distribution and Occurance of Udbatta Disease

Introduction

1. Udbatta disease is a minor disease of Rice crop.

2. The causal organism for Udbatta disease is Ephelis oryzae Syd

3. Local name for Udbatta diseases " Udubatti Roga"

4. Vernacular Name: Agarbatti, Mathapukaddi roga, Kari kaddi roga, Chipsu hode rogaek

5. This disease is endemic and of minor importance in certain areas in India.

History of Udbatta disease

File Courtesy: 
DRR Training Manual
Photo Courtesy: 
CRRI
7
Jul

Causal Organism, Management Options of Leaf Smut

Causal Organism:

  • The causal organism for Leaf Smut is Entyloma oryzae.

Management Options of Leaf Smut:

  • No control measures are recommended as it is not economically important disease.

Cultural practices of Leaf Smut: The cultural practices to control Leaf Smut are:

  • Deep ploughing after harvest.
  • Burning the infected debris
File Courtesy: 
http://agropedia.iitk.ac.in/?q=content/leaf-smut
7
Jul

Introduction, Economic Importance and Symptoms of Leaf Smut

Introduction:

1. Leaf smut is a minor fungal disease in which small slightly raised black spots develop primarily on the leaves.

2. Raised spots or pustules break open and release air-borne spores. Infection is often heavy enough to kill tips of leaves.

Economic importance of Leaf Smut

File Courtesy: 
http://agropedia.iitk.ac.in/?q=content/leaf-smut
Photo Courtesy: 
http://www.ipmimages.org/browse/detail.cfm?imgnum=5390514
7
Jul

Management Options – False Smut

Management practices to control of False Smut disease:

1. Cultivation of varieties that are found to be resistant or tolerant against the disease.

2. Destruction of straw and stubble from infected plants reduce the disease.

3. Applying Captan, Captafol, Fentin Hydroxide, and Mancozeb can inhibit conidial germination.

4. Fungicides, Propiconazole, Copper Oxychloride, Mancozeb and Chlorothalonil effectively reduce the incidence of the disease.

File Courtesy: 
DRR Manual
1
Jul

Pre-disposing factors of False Smut

 

Pre disposing factors for False Smut:

1. The disease is common and serious in temperate and cooler mountainous areas than in hot tropical regions.

2. In North western part of the country, it was reported to be serious in many of the hybrid rice growing areas.

3. It occurs more frequently in upland rice areas when a spell of wet weather synchronizes with the heading time.

4. High moisture favors the development of the disease. 

File Courtesy: 
DRR training manual (Dr. Krishnaveni)
1
Jul

Causal Organism, Symptoms and Host Plant Resistance of False Smut

Causal organism - False Smut

The  causal organism of False Smut disease is  

Ustilaginoidea virens (Cooke) Takah (anamorph), 

Claviceps oryzae-sativae Hashioka (teleomorph)

Symptoms of False Smut 

1.Symptoms of the false smut will be seen only after flowering.

File Courtesy: 
DRR training manual (Dr. Krishnaveni)
Photo Courtesy: 
DRR Training Manual
1
Jul

History, Distribution, Occurance and Economic Importance of False Smut

History of False Smut

1. False smut disease was reported by Cooke in 1878 from Tirunelveli districts of Tamilnadu.

2. Since then it has been reported from Japan, USA, Philippines and other countries.

Distribution and occurrence of False Smut

The disease occurs in severe and destructive form in Punjab, Uttar Pradesh, Haryana, West Bengal and Bihar states of India

Economic Importance - False Smut

File Courtesy: 
DRR Training Manual (Dr. D. Krishnaveni)
Photo Courtesy: 
CRRI, Cuttack
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