Disease:Yellow Mottle Disease

  • disease 38
  • disease 39
  • disease 40
  • disease 41
  • disease 42


  • In India, this disease was reported in 2003.
  • The disease has been observed in serious proportion in different parts of Kerala during the past few years and even up to 100% incidence was reported in certain black pepper plantations.
  • Though the disease has been noticed on all the cultivars, its incidence and severity is more in Karimunda and Panniyur 1.
  • The disease is characterised by vein clearing, scattered chlorotic flecks, followed by chlorotic mottling along veins leading to interveinal chlorosis and characteristic curling, twisting and deformation of leaves (Image1).
  • In a few cultivars, vein banding, vein thickening and green island-like symptoms are also seen (Image2).
  • Subsequently produced leaves are small, curled, twisted and brittle with bright interveinal chlorotic patches (Image3).
  • Intense interveinal chlorosis or yellow flecking of leaves results in poor spike and berry formation.
  • Internodes of vines become abnormally short leading to stunting of plants.
  • The infected vines have reduced vigour and yield.
  • They continue to decline and remain unproductive for a long period without dying..

Spread of Disease

  • It is transmitted through sap, cuttings, graftings, cutting knives and implements; and also through insect vectors like mealy bugs in a non-persistent manner. Various species of mealy bugs associated are Planococcus citri (citrus mealy bug), Psedococcus elisae and Ferrisia virgata (Foliar mealy bug). The virus is also transmitted by Diconocoris distanti (black pepper lace bug) (Image4,5).

Control Measures

  • Raise cuttings from disease free vines and also avoid normal vines from infected gardens.
  • As viral diseases of Black pepper are systemic in nature, the viruses are present in every cell of the plant and after entering into the vines, the viruses may even take 2 to 5 years to express the symptoms depending upon the varieties, age of vines, nature of virus(es), climatic conditions prevailing, vectors associated etc.
  • As the crop is vegetatively propagated, disease spread is rapid through the planting material, especially when infected plants are used as the source of planting material.
  • Separate and destroy diseased planting materials in nurseries. This helps to reduce the source of virus and its spread.
  • Uproot and burn the roots and infected vines in the field. This helps to reduce the disease spread through insect vectors as such vines serve as source of inoculum.
  • Avoid movement of planting materials from the infected regions to disease free zones.
  • Disinfect cutting knives and blades used for taking cuttings and other farm implements used in the affected field with phenol /dettol.
  • Do not prune off the infected plant parts alone, as it never eradicates the virus. Rather it exposes tools to infected sap.
  • Remove and destroy all the collateral hosts of virus and insect vectors from the pepper fields.
  • In order to avoid the spread of the disease through insect vectors, control vectors by spraying systemic insecticides like Monocrotophos (Nuvacron 1.5ml/L) or Dimethoate (Roger 1.5ml/L) at 3-4 weeks interval. If more number of sprays are required, adopt rotation of insecticides, rather than repeatedly sparying the same insecticide. Also, give waiting period before harvesting.