Turmeric: Diseases and Symptoms

Rhizome rot

The disease is soil-borne and rhizomes borne and occurs with the onset of monsoon. This disease mostly occurs during the months of June to September.

• The infection starts at the collar region of the pseudostem and progresses upwards as well as downwards.
• The collar region of the affected pseudostem becomes water soaked and the rotting spreads to the rhizome resulting in soft rot.
• At a later stage root infection is also noticed.
• Foliar symptoms appear as light yellowing of the tips of lower leaves which gradually spreads to the leaf blades.
• In early stages of the disease, the middle portion of the leaves remain green while the margins become yellow.
• Later, the yellowing spreads to all leaves of the plant from the lower region upwards and is followed by drooping, withering and drying of pseudostems.

• The disease is soil-borne. The fungus multiplies with buildup of soil moisture with the onset of south west monsoon.
• The fungus can survive in two ways: (a) in diseased rhizomes kept for sowing and (b) through resting structures like chlamydospores and oospores that reach the soil from infected rhizomes.
• Favourable conditions
• Younger sprouts are the most susceptible to the pathogen. Nematode infestation aggravates rhizome rot disease.
• Temperature above 30° C and high soil moisture are the important predisposing factors favouring the disease.
• Water logging in the field due to poor drainage increases the intensity of the disease.

Leaf spot

Disease is soil-borne noticed on the leaves from July to October.

• Symptom appears as brown spots of various sizes on the upper surface of the young leaves.
• The spots are irregular in shape and white or grey in the centre.
• Later, spots may coalesce and form an irregular patch covering almost the whole leaf.
• The centre of spots contains fruit head shaped fruiting structures.

• Disease is soil borne and survives in plant debris.
• The disease spreads through rain splashes during intermittent showers. The incidence of the disease is severe in turmeric grown under exposed conditions

• High soil moisture, temperature 25° C and leaf wetness.

Leaf blotch

• Disease symptom appears as small, oval, rectangular or irregular brown spots on either side of the leaves which soon become dirty yellow or dark brown.
• The leaves also turn yellow.
• In severe cases the plants present a scorched appearance and the rhizome yield is reduced.

• Soil and seed borne and survive in soil on infected plant debris.

• High soil moisture, temperature 25^O C and leaf wetness

Dry rot

• The disease causes root rot and rhizome rot resulting in typical dry rot of rhizomes from October onwards.
• The affected rhizomes appear soft and shrunken to start with, later dry up and become hard.
• Foliar yellowing and drying up of foliage which are the normal symptoms of maturity of the crop during October - November would be indistinguishable from the symptoms of the disease affected clumps.
• When infected rhizomes are cut open, the infected zones typically appear as dull brown and dark.

• The pathogen is facultative parasites and lives as a saprophyte on the organic matter in the soil for several years.
• It spreads from vulnerable plants

• The disease is favoured by 35° C soil temperature, 15-20 per cent soil moisture and alluvial or sandy soils.

Bacterial wilt

• Rapid wilting and death of the entire plant without any yellowing or spotting of leaves are the characteristic symptom.
• All branches wilt at about the same time.
• When the stem of a wilted plant is cut across, the pith has a darkened, water-soaked appearance.
• Greyish slimy ooze comes out on pressing the stem.
• In later stages of the disease, decay of the pith may cause extensive hollowing of the stem.

• The bacterium is especially destructive in moist soils at temperatures above 24° C.
• High soil temperature and moisture are favourable for disease.

IPM for Turmeric

To know the IPM practices for Turmeric, click here.

Source: NIPHM and Directorate of Plant Protection, Quarantine & Storage