11 Paddy Diseases: Understanding The Causes, Symptoms, And Treatment Options

Paddy diseases can have a devastating impact on rice production and farmers’ livelihoods. It is one of the most important food crops in India which covers 1/4th of the total cropped area. Rice is the staple food for more than half of the world’s population. India stands in the second position after China in global rice production. Total rice production in the year 2022-23 is 125 million tonnes. The total area under rice cultivation in 2022-23 is 45.5 million hectares with an average productivity of about 4.1 tonnes/ha. In India, Paddy is grown mostly during the Kharif season. It grows well in tropical and sub-tropical hot and humid climates.  

It is crucial to understand the causes, symptoms, and treatment options for paddy diseases to prevent their spread and minimize their impact. In this listicle, we will explore 11 common paddy diseases and what you need to know about them.

The scientific name of paddy: Oryza sativa 

11 Major Paddy Diseases:

1. Rice Blast or Blast of Rice:

Causal agent: Pyricularia oryzae (Sexual stage: Magnaporthe grisea) 

Affecting stages: All crop stages from seedling to late tillering and ear heading stage 

It is one of the most destructive Paddy diseases. The disease affects all parts of rice plants, mainly leaves, neck and nodes. It is expected to cause grain loss by 70 – 80%.  

Rice Blast Symptoms:  

• Leaf Blast Of Rice – Spindle-shaped spots with grey centre and brown margin, later causing a ‘Blasted’ or ‘Burnt’ appearance  

• Neck Blast Of Rice – Greyish brown lesions on the neck, panicle breaks and fall off 
• Node Blast Of Rice – Affected nodes show black lesions which later break up 

Favourable Conditions For Blast of Rice Disease: 

Areas having prolonged or frequent rainfall, lower soil moisture, cooler temperature and high relative humidity of about 93-99% are more susceptible to this disease.  

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2. Bacterial Leaf Blight Of Rice:

Causal agent: Xanthomonas oryzae 

Affecting stages: Tillering stage to Heading stage 

Bacterial Leaf Blight Of Rice Symptoms: 

• Water-soaked spots appear on leaves which gradually coalesce to form blotches and white streaks form from the tip of the leaf to the base. 
• Wilting and yellowing of leaves 
• Usually known as ‘Seedling wilt’ or ‘Kresek’ 

Favourable Conditions For Bacterial Leaf Blight Of Rice: 

Occurs mostly in irrigated and rainfed lowlands. The temperature of 25 – 34°C, Relative Humidity above 70%, high nitrogen fertilization, strong winds and continuous rainfall are favourable conditions for disease infection.   

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3. Sheath Rot Of Rice:

Causal agent: Sarocladium oryzae 

Affecting Stages: Boot leaf stage 

Sheath Rot Of Rice Symptoms: 

• Irregular greyish-brown water-soaked lesions on flag leaf sheath 
• White powdery fungal growth inside the affected sheath 

Favourable Conditions For Sheath Rot Of Rice: 

It is most prevalent during wet seasons compared to dry seasons. High nitrogen fertilization, plants with injuries and wounds, high relative humidity and temperature of 20 – 28°C, and closer planting density are some favourable conditions for disease incidence.  

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4. Brown Spot Of Rice:

Causal agent:  Helminthosporium oryzae 

Affecting Stages: Seedling to milky stage 

Brown Spot Of Rice Symptoms: 

• Oval or cylindrical dark brown spots with a yellow halo 
• Infection of florets can lead to incomplete grain filling and reduced grain quality 

Favourable Conditions for Rice Brown Spot: 

Relative Humidity above 86 – 100%, a temperature of 16 – 36°C, and infected seeds, weeds, and infected stubbles are some conditions favourable for disease infection.  

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5. False Smut Of Rice

Causal agent: Ustilaginoidea virens 

Affecting stages: Flowering stage to maturity 

False Smut Of Rice Symptoms: 

• Spikelets have orange or greenish-black velvety smut balls 
• This leads to chaffy grains 

Favourable Conditions For False Smut Of Rice: 

A temperature of 25 – 35°C, Relative Humidity above 90%, high nitrogen fertilization, heavy rainfall and winds are favourable conditions for false smut infection.  

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6. Sheath Blight Of Rice 

Causal agent: Rhizoctonia solani 

Affecting Stages: Tillering to heading 

Sheath Blight Of Rice Symptoms: 

• Initially, greenish-grey oval or elliptical lesions appear on the leaf sheath near the water level 
• Later, it forms irregular lesions with a greyish-white centre and brown margin 

Favourable Conditions for Sheath Blight Of Rice : 

The disease spread is more frequent during rainy seasons. High temperature, High Relative humidity, high nitrogen fertilization, and closer planting are favourable conditions for sheath blight infection. 

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7. Tungro Disease Of Rice

Causal agent: Rice Tungro virus (RTSV and RTBV) 

Affecting Stages: All growth stages especially the vegetative stage 

Vector: Leafhoppers 

Tungro Disease Of Rice Symptoms: 

• Stunted plants, yellow to orange discolouration in leaves. 

Favourable Conditions For Tungro Disease Of Rice: 

The presence of vectors, and virus sources through infected stubbles and weeds in the field are favourable conditions for RTV infection. 

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(Note: If the crop is infected with Rice Tungro Virus, it cannot be managed or cured. The below products can be used to control the vector and prevent it from spreading the virus in the paddy field)  

8. Foot rot / Bakanae / Foolish Seedling Disease Of Rice

Causal agent: Gibberella fujikuroi 

Affecting stages: Seedling to tillering stage 

Symptoms: 

• It affects both seedlings in the nursery and plants in the main field 
• Infected plants produce tall and thin tillers with yellowish-green and pale leaves. 

Favourable Conditions: 

Infected seeds, strong wind and water can create favourable conditions for disease infection. 

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9. Stem Rot Of Rice:

Causal agent: Sclerotium oryzae 

Affecting stages: Early tillering stage 

Stem Rot Of Rice Symptoms: 

• Initially, small black lesions appear on the outer leaf sheath 
• Later, the infected culm lodges, and produces chalky grains 

Favourable Conditions For Stem Rot Of Rice: 

Application of high nitrogen fertilizer, Infected stubbles, and plants with wounds as a result of insect attack may create favourable conditions for disease infection.  

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10. Grassy Stunt Disease Of Rice

Causal agent: Rice grassy stunt tenuivirus 

Affecting stages: All growth stages but most vulnerable at the tillering stage 

Vector: Brown plant hopper (BPH) 

Grassy Stunt Disease Of Rice Symptoms: 

• Stunted growth, excessive tillering 
• Grassy and rosette appearance of diseased hills 

Favourable Conditions For Grassy Stunt Disease Of Rice: 

Places, where rice is grown continuously and around the year, may create favourable conditions for the vector to spread the disease.  

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(Note: If the crop is infected with Rice grassy stunt disease, it cannot be managed or cured. The below products can be used to control the vector brown plant hopper (BPH) and prevent it from spreading the virus in the paddy field) 

Learn how to tackle Grassy Stunt Disease in paddy and protect your harvest. 

11. Rice Ragged Stunt Virus

Causal agent: Rice ragged stunt virus 

Affecting stages: All growth stages but most vulnerable at the tillering stage 

Vector: Brown plant hopper (BPH) 

Rice Ragged Stunt Virus Symtoms: 

• Leaves with uneven edges, leaf blade twisted into spiral shape at the base giving a ‘ragged’ appearance 
• Stunted growth, incomplete panicle emergence 

Favourable Conditions For Rice Ragged Stunt Virus: 

Areas where rice is grown continuously and all year round which provides a continuous host for the vector may create favourable conditions for the spread of disease.  

Buy Chemical Management For Rice Ragged Stunt Virus: 

(Note: If the crop is infected with Rice ragged stunt disease, it cannot be managed or cured. The below products can be used to control the vector brown plant hopper (BPH) and prevent it from spreading the virus in the paddy field) 

Protect your paddy crop from Ragged Stunt Disease. Click here for valuable information and practical steps to ensure crop safety!

Note: The information contained herein is for informational purposes ok of loss in crops and viewers are advised to do their own research before making any decisions.