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Crop Protection

Crop Protection
8
Jul

Varietal Resistance, Cultural Control and Chemical Control measures for Bacterial leaf

Varietal resistance of Bacterial Leaf Streak

1. BJ, TN1, Ptb 10, CR 1001, Zenith, TKM 6 are known to be resistant to bacterial leaf steak pathogen.

2. Resistance on BJ rice was governed by three pairs of independent resistant genes. (Nayak et al 1975).

Cultural practices to control Bacterial Leaf Streak

Cultural practices for the control of Bacterial Leaf Streak of rice

File Courtesy: 
DRR training manual ( Dr. Krishnaveni)
8
Jul

Management Options for Bacterial Leaf Streak

Management Options for Bacterial Leaf Streak

Bacterial Leaf Streak of rice management options includes

  • cultural practices,
  • chemical control and
  • the use of resistant varieties
File Courtesy: 
DRR training manual ( Dr. Krishnaveni)
8
Jul

Disease cycle of Bacterial Leaf Streak

Disease cycle of Bacterial Leaf Streak

1. The primary infection of the disease comes through infected seeds.

2. Secondary spread occurs through rain and irrigation water and also through contact between healthy and diseased plants.

3. The bacteria enter the host tissues through stomata or wounds, and multiply in the parenchymatous tissues.

 

File Courtesy: 
DRR training manual ( Dr. Krishnaveni)
7
Jul

Pre-disposing factors and Alternate hosts for Bacterial Leaf Streak

Predisposing Factors of Bacterial Leaf Streak

Factors which favor the development of Bacterial Leaf Streak of rice.

1. Strong winds, heavy rains, and deep water.

2. High temperature and humidity.

3. Presence of the bacteria on leaves and in water.

4. Sources of inoculum (volunteer plants, infected straws, weeds, etc.).

5. High amount of fertilizer application (excessive use of N).

6. Poor handling during transplanting (wounded leaves).

7. Closer plant spacing (high frequency of tissue contacts among plants).

File Courtesy: 
http://www.knowledgebank.irri.org/ricedoctor /index.php?option=com_content&view=arti cle&id=554&Itemid=2759
7
Jul

Causal organism and Symptoms of Bacterial Leaf Streak

Causal organism of Bacterial Leaf Streak

Causal organism for Bacterial Leaf Streak of rice is Xanthomonas oryzae pv. oryzicola

Symptoms of Bacterial Leaf Streak

1. The disease is observed late in the season on leaves, interveinal, translucent, water soaked narrow streaks appear, which gradually turn olive brown.

2. The number of streaks is more towards the tip of the leaf which coalesces and thereby resulting pre-mature drying of the leaf.

7
Jul

Distribution and occurrence of Bacterial Leaf Streak

Distribution and occurrence of Bacterial Leaf Streak

1. Bacterial leaf streak is widely distributed in Taiwan, Southern China, Southeast Asian countries, India, and West Africa.

2. This disease is transmitted through seeds.

3. Planting of infected seeds, which are collected from diseased fields produce diseased affected seedlings.

4. The bacteria, present in the water or those surviving in the debris left after harvest, are sources of inoculum for the next planting season.

File Courtesy: 
http://www.knowledgebank.irri.o rg/ricedoctor/index.php?option=co m_content&view=article&id=554&Itemid=2759
7
Jul

Bacterial Leaf Streak - Introduction and Economic Importance

Bacterial Leaf Streak

Introduction:

1. Bacterial Leaf Streak of Rice disease is usually observed during the tillering stage of the rice crop.

2. If the Bacterial Leaf Streak appeared in the later growth stages, the rice plant can easily recover and grain yield losses are minimized.

3. The disease is not reported to occur in temperate countries including Japan. The disease infection reduces the 1000 grain weight to the tune of 32.3%.

Economic importance of Bacterial Leaf Streak

File Courtesy: 
http://agropedia.iitk.ac.in/?q= content/baterial-leaf-streak-bls-rice
7
Jul

Pre disposing factors, Alternate host and Management options for Eye Spot

Predisposing factors of Eye spot

Factors that favor the development of Rice Eyespot disease is prolonged leaf wetness.

Alternate Host of Eye spot

Alternate hosts for Rice Eyespot disease are the Cynodon dactylon and Eleusine indica.

Management options of Eye Spot

Rice Eye spot can only be managed by using resistance rice cultivars.

File Courtesy: 
Google Book
7
Jul

Causal Organsim and Symptoms of Eye Spot

Causal Organism of Rice Eye Spot disease:

Causal organism for Rice Eyespot disease is "Drechslera gigantea".

Symptoms of Rice Eyespot disease:

1. Small size water soaked spots appear on the leaves and finally, olivaceous dots or rings.

2. A yellow halo frequently appears around young spots but later disappears.

3. Later spots develop into minute, longitudinally elongated, oval lesions with white to straw colored necrotic centres surrounded by narrow, dark brown margins.

File Courtesy: 
http://www.apsnet.org/publicat ions/PlantDisease/BackIssues/ Documents/1980Abstracts/PD_64_878.htm
7
Jul

Eye Spot - Introduction and History

Introduction to Eyespot

1. The Rice Eye spot has also been called Brown spot type disease

2. Causal organism for rice Eyespot disease is "Drechslera gigantea'

3. Prolonged leaf wetness favor the development of Rice Eyespot disease.

History of Eye Spot

1. The Rice Eyespot disease was observed on CICA 6 in Colombia, CICA 7 in Panama, and Naylamp in Peru.

File Courtesy: 
http://www.apsnet.org/publications/Pla ntDisease/BackIssues/Documents/198 0Abstracts/PD_64_878.htm
Photo Courtesy: 
http://aaqua.persistent.co.in/aaqua/forum/viewthread?thread=17779
7
Jul

Cultural practices to control Downy Mildew

Cultural practices to control Downy Mildew

The cultural practices to control Rice Downy Mildew disease:

1. Select and use only disease-free seeds for sowing. If possible, procure seeds that are resistant to downy mildew.

2. Transplant only healthy seedlings. Practice crop rotation. After harvest, plough-under all the plant debris.

3. Proper land preparation to make sure that soil is well drained.

File Courtesy: 
http://www.oisat.org/pests/diseases/fu ngal/downy_mildew.html
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
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