Ginger: Diseases and Symptoms

Soft rot

• The infection starts at the collar region of the pseudo stem and progresses upwards as well as downwards.
• Affected pseudo stem 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, the middle portion of the leaves remain green while the margins become yellow.
• The yellowing spreads to all leaves of the plant from the lower region upwards and is followed by drooping, withering and drying of pseudo Stems.

• The disease is soil-borne.
• The fungus can survive in two ways: (a) in diseased rhizomes kept for seed, and (b) through resting structures like chlamydo spores and oospores that reach the soil from infected rhizomes.
• The fungus multiplies with buildup of soil moisture with the onset of south west monsoon.

• Younger sprouts are the most susceptible to the pathogen. Nematode infestation aggravates rhizome rot disease.
• A high temperature above 30° C and high soil moisture are the important predisposing factors favouring the disease.
• Waterlogging in the field due to poor drainage increases the intensity of the disease.

Bacterial wilt

• Water soaked spots appear at the collar region of the pseudo stem and progresses both side upwards and downwards.
• The first conspicuous symptom is mild drooping and curling of leaf margins of the lower leaves which spread upwards.
• Yellowing starts from the lowermost leaves and gradually progresses to the upper leaves.
• In the advanced stage, severe yellowing and wilting symptoms occurs.
• The vascular tissues of the affected pseudo stems show dark streaks.
• The affected pseudo stem and rhizome when pressed gently extrudes milky ooze from the vascular strands. Ultimately rhizomes get rotted.

• Bacterial wilt is a soil and seed borne disease that occurs during south west monsoon.
• The bacteria are spread through soil, water, infected or contaminated rhizomes.
• The bacteria enter the plant through wounds made in the roots during transplanting, through agricultural equipment’s, nematodes and insects.

• Relatively high soil moisture and soil temperature
• Disease, occurs during south west monsoon.

Leaf spot

• The disease starts as water soaked spot and later turns as a white spot surrounded by dark brown margins and yellow halo.
• The lesions enlarge and adjacent lesions coalesce to form necrotic areas.

• Spread through wind and rain splashes.

• Disease is soil-borne; Noticed on the leaves from July to October; high humidity and temperature.

Storage rot

• Initially, disease appear as light yellowing of the tips of lower leaves which gradually spreads down to the leaf blade and leaf sheath along the margin.
• The middle portion of the lamina remains green while the margins become yellow.
• The yellowing spreads to all the leaves of plant from bottom upwards and is followed by drooping, withering and drying.
• The collar region of the pseudo-stem shows pale translucent brown colour which becomes water soaked, due to destruction of parenchymatus tissues.
• The infected plants can be easily pulled out from the rhizomes, the infection from the collar spreads to the rhizome gradually.
• The rhizome has a discoloured appearance before rot sets in the fi bro vascular strands are not affected.

• The fungus has been reported to be carried in seed-pieces or soils which are the source of primary infection.
• Secondary infection occurs by conidia

• High rainfall and poor drained soil favour in development of disease

Fusarium yellows/ yellow disease

• The infected plants remain yellow and stunted in growth.
• The yellowing start from lower leaves.
• From infection to total collapse is gradual.
• Infected plants produce shriveled tubers and brown ground tissue.

• Infected seed pieces and soil are source of primary inoculum.
• Resting spores i.e. chlamydo spores present in soil are source of secondary infection.

• High rainfall and poor drained soil favour in development of disease.

Sheath blight / leaf blight

• The lesions are usually observed on the leaf sheaths although leaf blades may also be affected.
• Initially, lesions are small, ellipsoid or ovoid, and greenish-gray and usually develop near the water line in lowland fields.
• Under favorable conditions, they enlarge and may coalesce to form bigger lesions with irregular outline and grayish-white center with dark brown borders.
• The presence of several large spots on a leaf sheath usually causes the death of the whole leaf.

• Fungus survives in the soil for many years in the form of sclerotia and spreads through soil & infected rhizomes

• The pathogen prefers warm wet weather and outbreaks typically occur in the early summer months most symptoms of the pathogen do not occur until late summer.

Dry rot

• Symptom includes discolouration of rhizome surface by fungal mycelia accompanied by dry rotting.

• Soil and infected rhizome pieces are source of primary inoculum.
• The fungus also produces resting structures (Chlamydospores) in the decomposing tissues of infected rhizomes. Therefore, tissues from infected crops remaining in the field serve as a reservoir of the fungus.

• The pathogen is known to prefer warm wet weather, coupled with high soil moisture.

IPM for Ginger

To know the IPM practices for Ginger, click here.

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