Rice

Rice Diseases and Their Control

Blight or Brown Spot

Symptoms: This disease has been recorded all over Pakistan. Initially small dots or circular eye shaped or oval spots appear light in colour on leaves. These spots coalesce and result in linear spots brown in colour. Later on withering and yellowing of leaves occur. Seed setting also affected and causes sterility, shrivelling and show rotting and poor germination.

Perpetuation: Diseased seeds, plant debris and soils help the fungus to survive, while air and irrigation water help to the fungus for transmitting from diseased to healthy plants.

Control:

  1. Use of resistant varieties or disease free seed in healthy soils,
  2. Sanitation and crop rotation,
  3. Hot water seed treatment at 54o C for 10 minutes or with seed dressing fungicides,
  4. Collection and destruction of stubble and spraying with copper fungicides at right time
  5. Application of suitable foliar fungicides may help to minimize further dissemination of the disease.

Bunt of Rice

Symptoms: This disease also called black or kernel smut is generally distributed wherever rice is grown. Diseased grains are filled with black powder, which can be detected by breaking them. Only a few grains may be affected wholly or partially in an ear. If not severely infected, seeds may germinate but seedlings are stunted.

Perpetuation: The disease causing organism is soil borne.

Control:

  1. Cultivation of resistant varieties,
  2. Use of healthy seed,
  3. Sowing early maturing varieties,
  4. Avoid high rates of nitrogen fertilizer,
  5. Avoid winnowing and threshing of diseased crop in field,
  6. Treat the seed with suitable chemicals easily available in the market and
  7. Collect and burn diseased ear heads.

Rice blast

Symptoms: Some times this disease refers as Pyrricularia blight or rotten neck, generally distributed where ever rice is grown. Small spots appear on leaves, nodes, panicles and grains and sometimes on leaf sheaths. The spots begin as small, water-soaked, whitish, greyish or bluish dots. These spots rapidly increase and become grey in center. Brown to black spots also develops on inflorescence and glumes. In later stages, diseased heads appear blasted and whitish in colour. Grain development is affected and the panicles droop.
Perpetuation: The disease perpetuates through diseased plant debris lying in the field, seed and wild grasses.

Control:

  1. Burn and destroy diseased plant debris and stubble,
  2. Early planting,
  3. Cultivation of resistant varieties,
  4. Use of healthy seed,
  5. Dusting the seed with any one of the organic mercurial seed dressing fungicides,
  6. Spray the crop with organo-mercurials,
  7. Avoid excessive depth application of irrigation water,
  8. Avoid excessive plant population and
  9. Control grasses and other weeds.

Bakanae Disease

Symptoms: This disease is also called white stalk, generally distributed where ever rice is grown. Infected seedlings are thin, chlorotic, may die before or after transplanting. In the field, infected plants have few tillers and leaves die in short time. Live plants have empty panicles. Some infected plants may be stunted instead of elongated, while the abnormal elongation of these (infected) plants in seed bed or field is most common symptom of this disease.

Perpetuation: The disease causing fungus is seed and soil borne, through which it can survive for a long period.

Control:

  1. Cultivation of resistant varieties and
  2. Seed treatment.

Major Insects Pests of Rice Crop

The insect pests that cause serious and economic damage are commonly known as major or important insect pests of rice and these major insect pests are given below with detail of their scientific name, family name and order name,

Rice Leaf Folder

The scientific or technical name of rice leaf folder is Cnaphalocrocis medinalis (Guenee) and it belongs to family Pyralidae and order Lepidoptera.

Damage

  1. 3 spices are found in sirlanka that causes damages.
  2. Leaf margins are folded and folded capsules and eat tissues by scarping. Paddy turns white, discolors and folded. Paddy is seems as malnourished and poor looking

Control

  1. Remove shade plant to provide strong sunlight. Apply nitrogen fertilizers as required.
  2. Use insecticides if the moth population is high to control larvae.

Rice Yield:

Pakistan is producing a good quantity of rice but the average yield in Pakistan is still behind the yield potential. One of the main reasons behind the lacking in rice yield is Pakistani farmers are still using the traditional practices of rice cultivation because of lack of knowledge about the latest innovations/practices. There is dire need to train the farmers about the latest practices i.e. Zero tillage of rice, direct seedling.

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