Greening : Liberobactor asiaticum ( Phloem limited bacteria)

Symptoms

• 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

Management

• Control psyllids with insecticides.
• Use pathogen free bud wood for propagation.
• 500 ppm tetracycline spray, requires fortnightly application.