Pest :Eriophyid Mite

Aceria guerreronis Eriophyidae

This mite is very small in size-about one fourth of a millimeter.As against the four pair of legs found in ordinary mites this has only two pairs.The mite is carrot shaped and white creamy in colour. It lays 20-100 eggs and hatch in two days. Life cycle of the mite is completed in 2 weeks. Colonies of the mites are seen in circles under the perianth cover in buttons, tender and also in immature coconuts.In a colony there will be about 1000 mites. Full grown mites move out and they spread to new bunches and neighboring trees aided by winds.Thus, the number of colonies develop within a short time.

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  • Eriophyid Image1
  • Eriophyid Image2
  • Eriophyid Image3

Symptoms

  • Mites suck the juice from buttons and also from tender nuts up to 6 months of age.
  • The earliest symptoms on 2-3 month old buttons are pale yellow triangular patch seen below the perianth.
  • Later these patches become brown.
  • Severely affected buttons may fall. The buttons (which are attacked and still retained on the trees) as they grow, develop brown to black necrotic lesions with longitudinal fissures on husk.
  • Uneven growth of the nuts results in distortion and stunting leading to reduction in copra yield.
  • The quality fibre is also reduced and the distorted nuts increase the labour requirement for de-husking.
  • A good number of young buttons fall down due to infestation.

Procedure for Observation

Select 20 trees at random from a plot and assess the % of trees showing damage.Less than 5 % mild, 5-10 % moderate .More than 10 % severe.

ETL

5 %.

Control Measures

  • Collect and destroy all fallen buttons of affected palms.
  • Apply 2% neem plus garlic emulsion or commercial formulation of Azadirachtin (0.004%- Neemazal T/S 1% @ 4 ml/l water) or micronized wettable sulphur (4 g/L) in the crown on young bunches.
  • When rocker sprayer is used 1.5 L of spray fluid is required per plant. While spraying, care should be taken not to direct the spray fluid on young inflorescence. Spray fluid should reach the perianth region of nuts.
  • Spray 3 times a year- March-April; August-September and December-January. So that all the emerging bunches in the vulnerable stage receive one round of spray.
  • Adopt a rational rotation of pesticide suggested to avoid pesticide resistance.
  • Spray Verticillium lecanii @ 20 g/L or 5 ml/L.
  • Apart from the above plant protection practices follow measures for improving plant health.
  • Method of preparation of 2% neem oil garlic emulsion.
  • To prepare 10 L
  • Neem oil 200 ml
  • Garlic 200 g
  • Bar soap 50 g
  • Mix 50 g bar soap in 500 ml lukewarm water. Grind 200 g garlic and take the extract in 300 ml water. Pour soap solution in neem oil slowly and stir vigorously to get a good emulsion. Mix garlic extract with the emulsion. Dilute the stock solution by adding 9 L water to get 10 L of 2% neem oil garlic emulsion.