Disease : KOKKAN

This viral disease has been reported from almost all banana growing areas in the State.

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Symptoms

  • Nendran is highly susceptible
  • The disease is also seen in Palayanakodan, Monthan, Poovan (Rasthali), Karpooravally, Chenkadali, Kanchikela etc.
  • Reddish/pinkish streaks of few mm to 10 cm length appear on the pseudostem, petiole and midrib
  • Later the pinkish streaks turn to dark brownish or blackish and become necrotic streaks which remain throughout the growth period
  • Numerous reddish/pinkish streaks make the entire pseudostem reddish or pinkish
  • Outermost leaf sheath will be more reddish or pinkish and it progress to the inner sheath as reddish or pinkish streaks
  • The outer leaf sheaths detach from the pseudostem in succession and break at the base
  • Leaves are arranged in both sides of the affected plant in a single plane giving a traveller s palm appearance
  • Leaves produced will be gradually reduced in size with reddish or pinkish petiole and midrib
  • Lamina shows mosaic mottling and becomes brittle
  • Affected plant produces only a small bunch with chlorotic to dark brown streaks on the bracts
  • The fingers are small, curved and widely divergent with pale green to ashy green colour as compared to healthy ones
  • The bunch never matures and fingers rot
  • The fingers take more time for ripening and pulp is unfit for consumption
  • New suckers from diseased plants show necrotic streaks or abnormal colour on the pseudostem

Procedure for Observation

Select five rows at random from 10 cent plot. Observe plants showing typical virus symptoms.

ETL

Mere presence

Spread of Disease

  • Primary spread through daughter suckers from the diseased plants.
  • Secondary spread through banana aphid Pentalonia nigronervosa .
  • Control Measures

    • The most important measure is to use only disease free planting material for propagation.
    • The diseases should be detected early in the field and immediately eradicate infected plants including suckers.
    • Affected plants can be destroyed by spraying kerosene or by injecting herbicides like 2-4 D
    • Do not take suckers from infected fields
    • Use tissue culture plants and certified disease free suckers for planting.
    • Avoid growing leguminous and cucurbitaceous vegetables as inter crops.
    • Before planting spread lemon grass in the pit,(if available)
    • Apply cartap hydrochloride 4 G @ 25 g per plant 20 days after planting. A second and third dose of the chemical are to be applied in the leaf axil @ 12.5.g each at 65 days and 165 days after planting.
    • Spray Verticillium lecanii to control aphid vectors @ 20 g or 5 ml /l at 25,65 and 165 days after planting . Where ever insecticides are applied 10 day gap should be given for biocontrol application.
    • Apply neemcake @ 1 kg in two split doses 25 -30 days after planting and the second at 60-65 days after planting.
    • Predators of banana aphids include lady bird beetles (Symnus nubilus, Pseudaspidimerus circumflexa , Micraspes crocea, Menochilus sexmaculatus) Syrphids (Paragus serratus, Ascarina spp.) and a Hemerobid. Protect these natural enemies.
    • Varieties such as Karpooravalli,kanchikela, Njalipoovn and koombillakannan are tolerant against bunchy top infection.