Major and minor disease of rice

Rice (Oryza sativa) as a cereal grain, it is the most widely consumed staple food for Asia. In India rice is a major crop . Almost every farmers cultivate rice in monsoon season. The disease result in loss of huge yield per year. The most common major and minor disease of rice are as follow.

1. Brown spot of rice

Caused by :-Helimenthosporium oryzae.

This is a major disease (epidemic) of rice.  It is a fungal disease that can kill whole leaf. It also infect leaf sheath, panicle, coleoptile, and spikelets. This disease was responsible for Bengal famine (1943) which leads to the death of 2 to 3 million .Brown spot disease can occur at all crop stages.

Symptoms or Identification of disease :-

 

  • The leaf and leaf sheath have brown ,round and oval spots.
  • The grains also become infected.
  • Fungi can also penetrate grains and hence discolored seeds or unfilled grains are formed (pecky rice) .
  • The disease is associated with a physiological disorder known as Akicchi (Japani form).
Management:-
  • Seed should be free from disease.
  • Use resistant variety.
  • Don’t use excess nitrogen fertilizer, silicon fertilizer can be used.
  • Since the fungus is seed transmitted , hot water treatment for 10-12 minutes can be ideal to use.
  • Use of fungicides like Carbendazim , Iprodione for seed treatment.

2. Sheath blight

Causal organism :- Rhizoctonia solani

Its also a fungal disease that reduced leaf area as leaves senesce or dry out and die more rapidly. Hence reduce grain yield because crop perform less photosynthesis. young tillers can also be infected. During the rainy season, plants are more favorable to this disease. Close planting can also favor disease development.

Symptoms or disease identification:-

  • on the leaf sheath, usually 1-3 cm long oval or ellipsoidal greenish gray lesions are formed.
  • Lesions have white center and light brown to dark brown
  • Lesions merge and cause the death of whole leaf.
  • Poorly filled or empty grains can be observed.
Management:-

This is also a fungal disease hence managements are almost same as brown spot of rice.

  • Destruction of infected crop debris.
  • Sanitation of soil.
  • Proper spacing.
  • Don’t use excess nitrogen fertilizer.
  • Spray Carbendazim @ 500g/ha or Tricyclozole @ 500g/ha

 

3. Blast of paddy

Caused by :-Pyricularia grisea (P.oryzae)

This disease is of 4 types

  1. Leaf blast
  2. Collar blast
  3. Node blast
  4. Neck blast

Symptoms:-

Leaf blast

Elliptical or boat shaped with brown border and grey centre.

Collar and node blast

The pathogens infects the collar that can ultimately kill the entire leaf blade.

Neck blast

The pathogen infects the neck of the panicle. The infected neck is girdled by a grey brown lesion and the panicle fall over.

If the infection is severe then the fungus produces two toxin U-Picolinic acid and Piricularin.

Management
  • Infected plants are destroyed.
  • Sanitation of soil.
  • Proper spacing.
  • Don’t use excess nitrogen fertilizer.
  • Spray Carbendazim @ 500g/ha or Tricyclozole @ 500g/ha

4. False smut or green smut of paddy

Caused by :- Ustilaginoidea virens

Smut is a seed born disease.

Symptoms

  • Individual rice grains transformed into a mass of yellow fruiting bodies.
  • velvety spores grown that close floral parts.
  • Only few grains in the panicle are infected and the rest are normal that’s why this is called false smut.
Management
  • Use of disease free seed
  • Removal or elimination of infected plant debris.
  • Sanitation of soil.
  • Proper spacing.
  • Don’t use excess nitrogen fertilizer.

5. Bacterial blight of rice

Bacterial blight is a bacterial disease and it is one of the most dangerous diseases of rice. When plants are infected at early stage, bacterial blight does not affect yield but results in poor quality grains

Caused by :- Xanthomonas oryzae

Symptoms

  • “Kresek” symptoms is seen.
  • In later stage blighting starts from tip of the leaves to the base.
  • Partially filled grains.
  • Since it is a bacterial disease bacterial ooze(a milky dew drops on young leaves) can be seen.
  • Straw turned yellow to white.
Management
  • Use of resistance variety.
  • Seed treatment with bleaching powder and zinc sulphate.
  • Field sanitation.
  • Use of balance fertilizer doses especially Nitrogen.
  • Spray Biltox.

6. Tungro Disease of rice

Local name :-Tungro virus rog

Pathogen:- Rice tungro spherical virus (RTSV)

Vector : leafhopper, The most efficient vector is the green leafhopper, it can transmit the viruses to other plants within 5−7 days.

Symptoms

  • Reduce tiller.
  • Delay flowering and maturity.
  • Yellow discoloration from leaf tip to leaf blade or lower leaf portion.
  • stunted growth.
Management
  • Use resistant variety.
  • Eradication of tungro host.
  • Elimination of vector by using traps(light trap).
  • Crop rotation.

Leave a Comment

Your email address will not be published. Required fields are marked *