Ginger: Insect and Nematode Pests Management

Shoot borer

• Egg: Eggs are pink, oval, flat laid singly or in group on leaves and other soft and tender part of the plant. The eggs hatch in 2-6 days.
• Larva: The larvae pass through 4–5 in stars and are full-fledged in 12- 16 days. Fully grown larvae are light brown with sparse hairs.
• Pupa: Pupation takes place inside the seed or sometimes in the grass that collects after feeding. Pupation takes place in lose silken cocoon in larval tunnel. The pupal stage lasts about 7-10 days.
• Adult: It is a medium sized moth with a wingspan of about 20 mm; the wings are orange-yellow with minute black spots. Three generations are completed in a year.

• The larvae bore into pseudo stems and feed on internal tissues resulting in yellowing and drying of leaves of infested pseudo stems.
• The presence of a bore-hole on the pseudo stem through which frass is extruded and the withered and yellow central shoot is a characteristic symptom of pest infestation.
• Favourable conditions:
• Temperature range 30-33°C and relative humidity range 60-90%.
• The pest population is higher in the field during September-October. The pest is most active from July to October.

Rhizome scale

• Female: Scales are circular (about 1mm diameter) and light brown to gray and appear as encrustations on the rhizomes.
• Male: It is orange coloured with transparent wings, distinct head, thorax and abdomen

• Adult (female) scales feed on sap and when the rhizomes are severely infested, they become shriveled and desiccated affecting its germination.
• In initial stage of infestation, the white coloured scales are seen scattered on rhizomes and later they congregate near the growing buds.
• When the infestation is severe the rhizome and buds shrivel and ultimately the entire rhizome dries.

• Dry weather

Leaf roller / skipper

• Egg: The female normally lays a single egg on undersides of leaves. The egg is reddish, smooth and dome shaped. When about to hatch it turns white with a red top
• Larva: The larva is greenish, sluggish & constructs its leaf shelter and comes out to feed only at night. Soon after hatching, the caterpillar does not consume the eggshell completely and it makes itself a spacious cell and hides inside it. It is smooth green with black head. Even when disturbed it is reluctant to leave its cell. Caterpillar of grass demon (threat) on turmeric
• Pupa: Pupation takes place on the same plant within a cell. The pupa is long and cylindrical, watery green in colour. It has a long conical projection in front of the head. The most striking characteristic of the pupa is its proboscis. It is long and thin generally extending up to and a little beyond the tip of the abdomen. The pupa is the same color of the larva and unmarked. It is covered in a thin layer of white powder. The body band is neither too tight nor too loose and allows the pupa to wriggle if disturbed.
• Adult: The adult moth are brownish black. It has forewings with a white spots and hind wing with a large white patch, emerge in February or March and lay eggs before they die.

• Leaves become folded or rolled longitudinally.
• Complete defoliation takes place in severe condition

• Temperature 26-35 °C, relative humidity 41-100%

Thrips

• Egg: Thrips reproduce by laying eggs.
• Nymph: Nymphs emerge from the eggs. It takes between 6-9 days to develop from eggs into adult thrips.
• Adult: Thrips are very small, have elongated abdomens and are yellowish or blackish in color. Although the adults have wings, these insect pests do not usually fly. They are often found on plants throughout all growth stages, from sprout development to tuber maturation.

• Thrips damage the undersides of leaves by sucking their plant sap.
• They damage young and soft parts of plants such as new leaves and shoots.
• Leaves become rolled up, and turn pale and gradually dry-up
• Severe infestation causes young leaves to wilt and dry out.

• Warm and humid weather

White grubs

• Egg: The females lay eggs singly on the main stem. The eggs are white, almost round in shape.
• Larva: The larvae are ‘C’ shaped, slow movers having globular head and elongated, dorsoventrally flattened body. The young grubs are translucent, white and 5 mm long.
• Pupa: Population takes place in the larval tunnel.
• Adult: Adults are about 18-20 mm long and 7-9 mm wide.

• Root grubs occasionally feed on tender rhizomes, roots and base of pseudostems causing yellowing and wilting of shoots.
• The grubs make large holes in rhizomes and reduce market value of produce.

• Warm and humid weather

Rhizome fly

• Egg: The eggs are small, white, cigar shaped, tapering at either side. The full grown larva is creamy white in colour, apodous and measures 9.5mm in length and 1.95 mm in breadth. Female fliers lay eggs singly or in clusters of 6-10 near the base of the plants under small lumps of soil, in cracks and on the surface or soil. The incubation period lasts for 2-5 days.
• Larva/ maggot: The larval period lasts for 13-18 days. The full-grown maggots pupate into rotten rhizomes.
• Pupa: The pupal period lasts for 10-15 days. The pupal period is for 10-15 days. The total period of life cycle is about 4 weeks.
• Adult: The flies are fairly large with slender body and long legs. The body is black in colour and wings are transparent with ashy spots. The wing expansion of flies varies from 13 to 15mm.

• The maggots feed on the rhizome as a result of which yellowing of plants and rotting of rhizomes takes place.
• Dead hearts due to primary injury, wilting and drying of aerial plants, can be seen.
• Rotting of rhizomes due to invasion of fungus, Pythium sp. through feeding injuries occurs.

• Warm and humid weather

Root knot, burrowing and lesion nematodes

• Root-knot nematode feed on tender rhizomes, roots and base of pseudostem causing stunting, chlorosis, poor tillering and necrosis of leaves are the common aerial symptoms.
• Characteristic root galls and lesions that lead to rotting are generally seen in roots.
• The infested rhizomes have brown, water soaked areas in the outer tissues.
• Nematode infestation aggravates rhizome rot disease.

• Nematodes survive in soil and infected rhizomes as primary inoculum.
• Therefore, tissues from infected crops remaining in the field serve as a reservoir of the fungus.
• It spreads from infected plants or through soil.

• Warm, moist soil are favourable conditions

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