Spices and Condiments: Chillies, Turmeric, Ginger, etc.

I. Ginger

Ginger is an important spice crop of India and accounts for 45 % of the world’s ginger production. It is also used in the preparation of medicines and confectionaries. It is mainly grown in Kerala and in a very small area in Karnataka, Tamil Nadu, West Bengal, Bihar, Himachal Pradesh, Uttar Pradesh and Maharashtra.

Insect Pests and its management:

1.Shoot borer (Conogethes punctiferalis)

The shoot borer is the most serious insect pest of ginger. The larvae bore into pseudostems and feed on internal tissues resulting in yellowing and drying of leaves of infested pseudostems. The presence of a bore-hole on the pseudostems through which frass is extruded and the withered and yellow central shoot is a characteristic symptom of pest infestation. The pest population is higher in the field during September-October. 

Control:

Spot out the shoots infested by the borer. Cut open the shoot and pick out the caterpillar and destroy. Spray neem oil (0.5%) at fortnightly intervals if found necessary. Light traps will be useful in attracting and collecting the adult moths.

2.Rhizome scale (Aspidiella hartii) 

It infests rhizomes in the field (at later stages) and in storage. It feeds on sap and when the rhizomes are severely infested, they become shriveled and desiccated affecting its germination. 

Control:

Apply well rotten sheep or poultry manure@4t/acre in two splits. Along with it add 100kg of neem cake.

Diseases and the control measures:

1. Soft rot or rhizome rot caused by Pythium aphanidermatum:

• It is the most destructive disease of ginger which results in total loss of affected clumps. The disease is soil-borne and is caused by Pythium spp. Younger sprouts are most susceptible to the pathogen.
• 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 with characteristic foul smell.
• At a later stage root infection is also noticed. Foliar symptoms appear as light yellowing of the leaf margins of lower leaves which gradually spreads to the leaf lamina.
• In early stages of the disease, 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 pseudostems.

Control measures:

• While selecting the area for ginger cultivation care should be taken to see that the area is well drained as water stagnation pre-disposes the plants to infection. Hence provide adequate drainage.
• Select seed rhizomes from disease free areas since this disease is also seed borne.
• Solarisation of soil done at the time of bed preparation can reduce the fungus inoculum. However, if the disease is noticed, the affected clumps are to be removed carefully along with the soil surrounding the rhizome to reduce the spread.
• Trichoderma may be applied at the time of planting and subsequently if necessary.
• Restricted use of Bordeaux mixture (1 %) in disease prone areas may be made to control it. 

2. Bacterial wilt caused by Ralstonia solanacearum:

It is a soil and seed-borne disease that occurs during the south-west monsoon. Water soaked spots appear at the collar region of the pseudostem and progresses upwards and downwards.

• The first conspicuous symptom is mild drooping and curling of leaf margins of the lower leaves which spread upwards.
• In the advanced stage, the plants exhibit severe yellowing and wilting symptoms.
• The vascular tissues of the affected pseudostems show dark streaks. The affected pseudostem and rhizome when pressed gently extrudes milky ooze from the vascular strands. Ultimately rhizomes rot emitting a foul smell. 

Control measures:

• The cultural practices and seed rhizome treatment adopted for managing soft rot are also to be adopted for bacterial wilt.
• Seed rhizomes must be taken from disease free fields for planting.
• It is not advisable to plant ginger consecutively in the same field every year. Fields used for growing potato, or other solanaceous crops are to be avoided.
• Once the disease is noticed in the field the affected clumps may be removed carefully without spilling the soil around and the affected area and surrounding areas drenched with copper oxychloride 0.2%.
• Care should be taken to dispose of the removed plants far from the cultivated area or destroyed by burning. 

3. Leaf spot caused by Phyllosticta zingiberi:

• The disease starts as a 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.
• The disease spreads through rain splashes during intermittent showers.
• The incidence of the disease is severe in ginger grown under exposed conditions. 

Control measures:

• The disease can be controlled by spraying Bordeaux mixture 1% or mancozeb 0.2% or carbendazim 0.2%, with the appearance of disease symptoms.
• Care should be taken to see that the spray solution should reach the lower surface of the leaves also. 

4. Nematode pests:

• 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. 

Control measures:

• The nematodes can be controlled by treating infested rhizomes with hot water (50°C) for 10 minutes, using nematode free seed rhizomes and solarizing ginger beds for 40 days.
• In areas where the root knot nematode population is high, the resistant variety IISR-Mahima may be cultivated.
• Pochonia chlamydosporia, a nematode biocontrol agent can be incorporated in ginger beds (20 g/bed with 106 cfu/g) at the time of sowing.