Rice

Nematodes

Rice White Tip Root Nematode

Rice white tip nematode – Aphelenchoides besseyi

  • This nematode is widely distributed in Tamilnadu.
  • In its preadult stage it is carried by the paddy grains beneath the hull and at this stage it can remain alive for about four years.
  • When nematode carrying seeds are sown, the immature forms become active, move up the plant along a thin film of moisture and feed on the foliage ectoparasitically.
  • The leaf tips of the affected rice plants turn yellow brown and finally white for 2 to 5 cm which then deries up and hangs down.
  • Tips of developing leaves become twisted and crinkled.
  • In extreme cases the affected grains become chaffy.

Management

  • Usage of nematode free seeds and planting material from nematode free fields.
  • Presoaking overnight and sun drying for 12 hours at 6 hrs/day for two days, two or three days prior to sowing to denematize the seeds.
  • Hot water treatment of seed with 52 -53 degree C for 15 minutes can be used to destroy this nematode infecting the seeds.
  • Apply carbofuran 3G in nursery @ 1.0 kg a.i/ha 7 days before transplanting.
  • Apply cartaphydrochloride @ 1.0 kg a.i/ha at 45 DAT

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Rice Root nematode - Hirschmanniella oryzae, H. mueronata

  • This is migratory endoparasite
  • The nematode enters the root and feeds on the parenchyma which results in the formation of cavities in the root.Infested roots show discoloration and partially hollow.
  • Feeding adversely affects absorption of water and nutrients and thus plants show stunted growth in patches. Tillers reduced upto 8

Management

Nursery

Application of carbofuran 3 G at 3.5 kg/20 cent nursery.

Mainfield

  • Apply Carbofuran 3 G 16.25 kg in 2 cm standing water.
  • Treat Pseudomonas fluorescens at 10 and 20 g/kg of seed to protect against rice root nematode.

Rice root-knot nematode, Meloidogyne graminicola

Symptoms:

  • Characteristic symptom is the hook -like galls on roots.
  • Newly emerged leaves appear distorted and crinkled along the margins.
  • Stunting of plants in patches Chlorosis on leaves is a marked symptom.
  • In heavily infected plants flowering and maturity takes place early.
  • Number of tillers are reduced. Ear head size is reduced and number of grains also reduced.

Management

  • Keep the crop always in submerged conditions Continuous flooding, raising the rice seedlings in flooded soils and crop rotation practices will help to prevent root invasion by the nematodes.
  • Soil solarization, with 50 - 100µ clear polythene sheets for 3 weeks before preparation of fields will also control the nematodes.

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Tamilnadu

Rice

Rice Management