Citrus greening : a deadly fruit disease

Citrus greening disease is an important disease of citrus which greatly affects the production of the fruits in several parts of India.

Characteristic symptoms include yellowing of leaf veins and adjacent tissues, followed by premature defoliation, dieback of twigs, decay of feeder rootlets and lateral roots.

Infected fruits are small, lopsided with bitter taste. Such fruits may fall prematurely; while those that remain on the tree do not colour properly, remaining green on the shaded side.

Management

Routinely scout citrus for signs of greening so that infected trees can be removed. Scouting should be done at least four times a year, or more in areas known to have infected trees. October through March is the best time for scouting, but symptoms can be present at other times of the year.

For effective management remove infected trees. This is the only way to ensure that they won’t remain a source of infection for other trees. Pruning symptomatic limbs is often ineffective since other parts of the tree may be infected, but do not show symptoms.

Before removing, the tree should be sprayed with a foliar insecticide to kill any psyllids in order to keep them from moving on once the tree is removed.

Focus Integrated Pest Management (IPM) efforts on using disease-free nursery trees, reducing infection sources (inoculum) by frequent surveys and diseased tree removal, and suppressing Asian citrus psyllid through area-wide management

Foliar spray

Spray foliar insecticide prior to tree removal. Increase frequency of scouting in areas where infected trees have been removed

The complex of natural enemies attacking ACP around the world usually includes various species of ladybeetles, syrphid flies, lacewings, spiders.

Use soil-applied systemic insecticides on young trees. Foliar sprays of fenpropathrin (Danitol 2.4 EC), chlorpyrifos (Lorsban 4EC), petroleum oil (2 per cent rate).

(Utpal Dey, Ph.D. scholar, Department of Plant Pathology and Dr A.P. Suryawanshi, Head in charge, Department of Plant Pathology, Marathwada Agricultural University, Parbhani, Maharashtra, India, email: utpaldey86@gmail.com, mobile: Mob : 8275824103.)