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Nematode pest of crops : cereals


Rice

A. Rice root-knot nematode, Meloidogyne graminicola 

Symptoms

  • Characteristic hook -like galls on roots
  • Newly emerged leaves appear distorted and crinkled along the margins
  • Stunting in patches
  • Chlorosis
  • Heavily infected plants flower and mature early
  • Reduction in no. of tillers
  • Size of the ear head  is reduced with reduced no. of grams

Management

  • Keep the crop always in submerged conditions
  • Cultural control includes continuous flooding, raising the rice seedlings in flooded soils.
  • And crop rotation These practices will help prevent root invasion by the nematodes.
  • Soil solarization, with 50 – 100µ clear polythene sheets for 3 weeks before preparation of fields.

Rice root nematode,  Hirschmanniella oryzae, H. mueronata 

Symptoms

  • Infested roots show discoloceration and partially hollow.
  • Feeding adversely affects absorption of water and nutrients.
  • Plants show stunted growth in patches.
  • Reduced on 8 tillers

Management 

  • Nursery treatment with carbofuran @ 1.0 kg ai/ha.

Rice white tip nematode: Aphelenchoides besseyi
Symptoms

  • Feeding at leaf tips in rice results in whitening of the top 3-5 cm of the leaf, leading to necrosis. There is also distortion of the flag leaf that encloses the panicle.
  • Diseased plants are stunted, lack viguor and produce small panicles. Affected panicles show high sterility, distorted glumes and small and distorted kernels.
  • In the seed-bed, emergence of severely infected seedlings is delayed and germination is low. 
  • The most conspicuous symptoms occur at the tillering stage. 
Tip affected
White tip symptom in field
White tip affected in large area

Management

  • Preventative Measures - Aphelenchoides besseyi infestations can be avoided by using nematode-free seeds and planting in nematode-free fields.
  • Hot water treatment of seed can be used to destroy this nematode infecting the seeds, found that thermal wet treatment was the most effective. Aphelenchoides besseyi was not recovered from rice seeds which received hot water treatment at 55-60 C for 15 minutes, but was observed in seed subjected to hot water treatment at 50 C. lower temperatures (52-53 C for 15 minutes) for hot water treatment have been reported.
  • Apply cartaphydrochloride @ 1.0 kg a.i/ha at 45 DOP
  • Apply carbofuran 3G in nursery @ 1.0 kg a.i/ha 7 days before transplanting.

 


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