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Diseases

Diseases
9
Jul

Cultural Control for Rice Tungro Disease

Cultural Control for Rice Tungro Disease

1. Adjustment in agronomic practices enables rice crop to become tolerant with increase in age of the crop.

2. In general even a susceptible variety does not take up the infection beyond 75 days of age.

3. Young seedlings in the nursery are more vulnerable for the attack by the vectors as well as infection by virus.

4. Sowing time should be so adjusted to avoid peak population of vectors.

File Courtesy: 
DRR training manual ( Dr. Krishnaveni)
9
Jul

Control measures, Host Plant Resistance of Rice Tungro Disease

Control measures of Rice Tungro Disease

Rice tungro disease control measures include

  • cultural control,
  • chemical control and
  • use of resistant varieties.

Host-Plant Resistance of Rice Tungro Disease

1. To control tungro virus, the ideal method is to grow resistant varieties, especially in the endemic areas to disseminate the primary infection and primary infected areas, so that moderately resistant varieties can be harvested with minimum damage and little loss in yield.

9
Jul

Predisposing factors of Rice Tungro Disease and Rice Tungro Virus

Predisposing factors of Rice Tungro Disease

Factors for the development of Rice Tungro Disease

1. The outbreak of rice tungro disease is the result of several factors like availability of virus source (primary inoculum), presence of host susceptible to both virus and vector, right growth stage of the host, availability of vectors and favourable climatic conditions.

2. Shortage of irrigation water may also promote tungro incidence because farmers are forced to plant asynchronously.

Rice Tungro Virus

File Courtesy: 
http://jvi.asm.org/cgi/content/full/74/5/2073
9
Jul

Symptoms of Rice Tungro Disease

Symptoms of Rice Tungro Disease

1. Infection at the early stage usually causes more stunting. Initial symptoms of Rice tungro virus infection are inter-veinal chlorosis and twisting of infected leaves.

2. The leaf discolouration may vary from greenish yellow to reddish brown or yellowish brown.

File Courtesy: 
DRR training manual ( Dr . Krishnaveni)
Photo Courtesy: 
DRR training manual ( Dr . Krishnaveni)
9
Jul

Rice Tungro Disease (RTD) - Introduction and History

Introduction

1. Among the virus diseases that affect Rice, tungro disease is widely prevalent, particularly, in the North Eastern and Eastern coastal region of Peninsular India.

2. The word ‘tungro’ in tagallo, a language in The Philippines, means degenerated growth, causing leaf discoloration which varies from light green to orange yellow leaves, reduction in tiller number and stunted plant growth.

File Courtesy: 
DRR MANUAL
Photo Courtesy: 
Dr.Krishnaveni DRR
9
Jul

Causal Organism and Symptoms of Sheath Brown Rot

 Causal Organism of Sheath Brown Rot

  • Causal organism for Sheath brown rot is caused by Pseudomonas fuscovaginae Miyajima

Symptoms  of  Sheath Brown Rot

1. Symptoms appearing at seedling and later stages include discoloration and rotting of sheath. 

File Courtesy: 
http://www.knowledgebank.irri.org/smta/index.ph p?option=com_content&view=article&id=279&c atid=35&Itemid=84
Photo Courtesy: 
http://www.knowledgebank.irri.
9
Jul

Sheath Brown Rot - Introduction, Distribution and Occurance

Introduction to Sheath Brown Rot

File Courtesy: 
http://www.knowledgebank.irri.org/smta/inde x.php?option=com_content&view=article&id =279&catid=35&Itemid=84
9
Jul

Pecky Rice

Pecky Rice (Kernel Spotting)

  • Pecky rice is also called as kernel spotting.

Distribution and occurrence of Pecky Rice

  • Single or several florets in the panicle develop brown to reddish-brown spots; grain discolored due to feeding of stink bugs and fungal growth.

Causal Organism of Pecky Rice

Many fungi cause damages

File Courtesy: 
http://en.wikipedia.org/wiki/List_of_rice_diseases
8
Jul

Grain Rot - Economic Importance, Causal Organism and Symptoms

Economic importance of Grain Rot

There is no exact estimate of losses caused, by this disease but 900,000 ha of rice in North Kyushu Island (Japan) have been infected by the disease.

Causal organism of Grain Rot

The Grain rot disease is caused by Burkholderia glumae.

Symptoms of Grain Rot

1. Bacterial grain rot symptoms appear on seedlings and spikelets.

2. Seedlings raised in boxes turn brown and rot.

3. The glumes (lemma) of infected spikelets are discolored.

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
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