Acid lime variety is highly susceptible to citrus canker. Yield losses range from 5 to 30 per cent, depending upon the variety. The disease attacks seedlings and grown up trees.
In young plants in the nursery, the disease causes serious damage. Badly cankered leaves fall down and in serious infestation the entire plant dies.
The disease affects leaves, twigs, thorns, older branches and fruits. On the leaves the disease first appears as a small, watery, translucent yellow coloured spot.
As the spots mature, the surface becomes white or grey in colour and finally ruptures in the centre giving a rough, hard, corky and crater-like appearance.
Gumming
The infection spreads to the fruits on which spots are formed. The cankers may be scattered all over the surface or several cankers may occur together forming an irregular scurfy mass. Gumming is sometimes associated with spots on fruits.
Canker has never been observed occurring naturally on roots of even badly diseased trees. However the disease has been found on grape fruit roots exposed above ground surface.
Management
-Dropped off canker affected leaves and twigs should be collected and burnt.
Disease-free nursery stocks should be used for planting in new orchards.
The plants before planting in new orchards should be sprayed with Bordeaux mixture 1.0 per cent.
In old orchards pruning of affected plant parts before the onset of monsoon and spraying with Bordeaux mixture 1.0 per cent at periodical intervals depending upon weather conditions controls the disease.
-Spraying should be done immediately after the appearance of every new flush of leaves.
The vigour of the plant should always be maintained by proper fertilization and irrigation.
Manuring should be done in such a way that its maximum effect is felt during wet weather.
(Utpal Dey, Ph.D. scholar and A.P. Suryawanshi, Associate Professor, Department of Plant Pathology, College of Agriculture, V.N. Marathwada Krishi Vidyapeeth, Parbhani - 431402, Maharashtra, Mobile: 8275824103)
