Citrus diseases and their control

Major Citrus diseases are given below:-

1.Gummosis: Phytophthora parasitica, P. palmivora,P. citrophthora

citrus gummosis
  • First symptoms are dark staining of bark which progresses into the wood.
  • Bark at the base is destroyed resulting in girdling and finally death of the tree.
  • Bark in such parts dries, shrinks and cracks and shreds in lengthwise vertical strips.
  • Later profuse exudation of gum from the bark of the trunk.
  • Infection extends to crown roots.
  • Prolonged contact of the trunk with water as in flood irrigation; water logged areas and heavy soils.
  • Soil inhabitants.
  • Sporangia spread by splashing rain water, irrigation water and the wind.
  • Irrigation water and wind.
  • Injuries to crown roots or base of the stem during cultural operations should be avoided.
  • If the lesion has girdled less than ½ the girth, remove the diseased bark with a knife along with ½” of uninvaded bark.
  • The bark of trunk should be coated with Bordeaux paste.


2.Scab/Verucosis: Elsinoe fawcetti

citrus scab
  • Attacks leaves, twigs and fruits of mandarin.
  • Sour orange, lemon, mandarin, tangelos extremely susceptible Grapefruit, sweet oranges and acid lime highly resistant. Severe in rainy seasons.
  • On the leaves, the disease starts as small pale orange coloured spots.
  • The leaf tissue is distorted to firm hollow conical growths with the lesion at the apex.
  • The crest of these growth becomes covered with scabby corky tissue colour at first but later becomes dark olive with age.
  • Lesions most common on the undersurface of the leaf. They penetrate leaf and are later visible on both sides.
  • Infected areas run together and cover a large area.Leaves wrinkled, distorted and stunted.
  • On twigs, similar lesions are produced.
  • They form corky outgrowths.On fruits irregular scably spots or caked masses produced.
  • Cream colour in young fruits; dark olive grey in old fruits.
  • Fruits attacked when young become misshapen with prominent warty projections. They drop prematurely.
  • Spray Carbendazim 0.1%


3.Citrus Canker: Xanthomonas campestris pv citri

canker in citrus fruit
canker on fruit
canker of citrus
canker on leaf
  • Acid lime, lemon and grapefruit are affected. Rare on sweet oranges and mandarins.
  • Affects leaf, twig and fruits. In canker, leaves are not distorted.
  • Lesions are typically circular with yellow halo; appear on both sides of leaf, severe in acid lime (difference from scab) When lesions are produced on twigs, they are girdled and die.
  • On fruits, canker lesions reduce market value.
  • Streptomycin sulphate 500-1000 ppm; or Phytomycin 2500 ppm or Copper oxychloride 0.2% at fortnight intervals.
  • Control leaf miner when young flush is produced.
  • Prune badly infected twigs before the onset of monsoon


4.Tristeza or quick decline: Citrus tristeza virus (CTV)

citrus tristeza

  • Lime is susceptible both as seedling or buddling on any root stock.
  • But mandarin and sweet orange seedlings or on rough lemon, trifoliate orange, citrange; Rangpur lime root stocks tolerant; susceptible root stocks are grape fruit and sour orange.
  • In sweet orange or mandarin on susceptible root stocks, leaves develop deficiency symptoms and absise.
  • Roots decay, twigs die back. Fruit set diminishes; only skeleton remains.
  • Fine pitting of inner face of bark of sour orange stock.
  • Grapefruit and acid lime are susceptible irrespective of root stock.
  • Acid lime leaves show large number of vein flecks (elongated translucent area).
  • Tree stunted and dies yield very much reduced. Fruits are small in size.
  • Use of infected bud wood and Toxoptera citricida (aphid) is the important vector.
  • For sweet orange and mandarin, avoid susceptible root stocks.
  • For acid lime, use seedling preimmunised with mild strain of tristeza.


5.Greening : Liberobactor asiaticum ( Phloem limited bacteria)

greening of citrus

  • This disease affects almost all citrus varieties irrespective of root stock.
  • Stunting of leaf, sparse foliation, twig die back, poor crop of predominantly greened, worthless fruits.
  • Sometimes only a portion of tree is affected.A diversity of foliar chlorosis.
  • A type of mottling resembling zinc deficiency often predominates.
  • Young leaves appear normal but soon assume on outright position, become leathery and develop prominant veins and dull olive green colour. Green circular dots on leaves.
  • Many twigs become upright and produce smaller leaves.
  • Fruits small, lopsided with curved columella. The side exposed to direct sunlight develops full orange colour but the other side remain dull olive green.
  • Low in juice and soluble solids, high in acid. Worthless either as fresh fruit or for processing. Seeds poorly developed, dark coloured, aborted.
  • Infected budwood; psyllid vector-Diaphorina citri
  • Control psyllids with insecticides.
  • Use pathogen free bud wood for propagation.
  • 500 ppm tetracycline spray, requires fortnightly application.




  • TamilNadu Agritech Portal



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