CARDAMOM

Plant protection-Nursery

Pests

1. Rhizome weevil ( Prodioctes haematicus )
2. Shoot fly ( Formosina flavipes )
3. Shoot borer
4. Root grubs (Basilepta fulvicorne)
5. Spotted red spider mite
6. Cutworm ( Acrilasisa plagiata )
7. Plant parasitic nematodes

Diseases

1. Nursery leaf spot
2. Nursery leaf rot
3. Damping off or seedling rot
4. Clump rot ( Rhizome rot )
   

Rhizome weevil ( Prodioctes haematicus )

This is a serious pest in the secondary nursery especially where seedlings are raised continuously year after year. The grubs feed on the rhizome and basal portion of the stem. This results in drying of leaves and breaking of stem at the base.

Management:

Drenching the nursery beds with chlorpyrifos at 0.04% can control the pest.

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Shoot fly ( Formosina flavipes )

The pest is observed in the nursery during January to May. Dead-heart or decay of the central spindle is the external symptom. Management: Spraying of quinalphos 0.025% or application of phorate granules @ 1 g ai/m 2 is recommended for the control of the pest.

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Shoot borer ( Conogethes punctiferalis )

The caterpillar bores into the stem and feeds on the internal contents. This results in the decay of the central spindle and production of dead heart. Faecal matter of the caterpillar can be seen coming out through the holes

Management:

Spraying with quinalphos 0.025%, carbaryl 0.1%, monocrotophos, fenthion or dimethoate at 0.05% or phenthoate at 0.1% is recommended against the shoot borer.

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Root grubs (Basilepta fulvicorne)

The grubs of the insect cause damage. The grubs are small, 2-10 mm long, off-white in colour and often assume a shape resembling 'C'. Grubs feed on cardamom roots in patches. This reduces the uptake of nutrients and leads to yellowing of leaves.

Beetles are small greenish blue or blue or green and are found in large numbers during May to July and October to February. A female beetle lays 124-393 eggs in batches on dry grass, leaf sheath, mulch or dry cardamom leaves, during its life span of nearly 85 days. Grubs drop down and enter into the soil and start feeding on cardamom roots. Grub stage lasts for 45 to 60 days or 80 to 120 days depending on season i.e., May to July or October to February respectively. They make earthen cells and become pupae inside the cell. Adults come out from these earthen cells as beetles.

Management:

•  Beetles may be collected and destroyed during March-April and August- September.

•  Early stages of the grub which are usually present in soil during May-June and September-October can be controlled either by drenching chlorpyrifos 0.04 % @ 3-4 litres/clump or by applying phorate @ 30-40 g per clump. The granules may be spread up to 10 to 15 cm around the plant base and incorporated in the soil. Adequate moisture must be available in the soil at the time of application of phorate.

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Spotted red spider mite

Spider mite at times assumes the status of a serious pest during summer. These mites spin web and colonize behind it on under surface of leaves. They suck plant sap from leaves resulting in the formation of grey blotches on leaves. The infected portion of the leaf with its delicate silky threads, eggs and excreta look ashy white and dusty. The affected leaves gradually dry up. These mites may also infest tillers and panicles. About 15-20 days are required to complete its life cycle.

Management

•  Spraying dicofol @ 200 ml/100 litre water or sulphur 80 WP 250 g/100 litre or dimethoate @ 167 ml/100 litre or phosalone 200 ml/100 litre on lower surface of leaves is effective against this pest. Spraying may be repeated 2 or 3 times at 15 days interval depending on severity of infestation.

•  As a precaution, use of organochlorine insecticides and pyrethroids may be avoided in cardamom plantation.

•  Excess use of nitrogenous fertilizers may be curbed.

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Cutworm ( Acrilasisa plagiata )

Cutworms feed on leaves of seedlings. Infestation is noticed usually during January-March. The caterpillar is nocturnal in habit. It pupates in soil. Pupal period lasts for 17 days.

Management:

Collection and destruction of caterpillars and pupae combined with spraying monocrotophos or endosulfan 0.1% in the evening hours at the base of the seedlings will control the pest.

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Plant parasitic nematodes

Root-knot nematode Meloidogyne incognita is a serious problem in cardamom. They are present both in the nurseries and plantations of the entire cardamom growing tracts of South India. They feed on the roots; make the plants weak and vulnerable to diseases. In their presence the nursery diseases like rhizome rot and damping off due to Rhizoctonia solani get aggravated.

Symptoms:

1. Poor germination of seeds in the primary nurseries.

2. Poor establishment after transplanting to secondary nurseries or main fields.

3. Yellowing and drying of leaf tips and margins.

4. Stunting and poor growth of the plants.

5. Shedding of immature capsules in the main field.

6. Heavy galling (root-knots) and abnormal branching of roots (Galling is prominent in seedlings while in the mature plants the galls are small in size with abnormal branching of roots which are devoid or rootlets).

Management:

The most important step is the production and distribution of healthy, nematode-free seedlings. For this the following measures may be adopted.

1. Fumigate the primary and secondary nursery beds using methyl bromide (@500 g/10 m 2 ) or ethylene-dibromide (@ 20 l/ha) or durofume (@30 l/ha) under polythene cover for 2-3 days or drench the nursery beds with 2% formalin.

2. Treat the plants in the nursery with carbofuran 3G @ 5 kg ai/ha, (i.e. 1 g ai per row of 6 m length) after 10 days of germination and this is repeated after 3 months. In secondary nurseries the plants may be treated along the rows with carbofuran @10 kg ai/ha after transplanting and every three months thereafter.

3. Do not use the same site repeatedly for raising the seedlings. If possible, rake the soil of the site and expose to sunlight before taking up sowing. The roots should be pruned prior to distribution or transplanting.

Diseases

Nursery leaf spot

Leaf spot caused by the fungus Phyllosticta elettariae is a destructive disease especially in nurseries of Karnataka area. In other areas it is a minor disease. It appears mostly during February-April months with the receipt of summer rains. Disease appears as small round or oval spots, which are dull white in colour. These spots later become necrotic and leave a hole (shot hole) in the centre. The spots may be surrounded by water soaked area. High intensity of disease is noticed in open nurseries exposed to direct sunlight. In such cases, numerous spots develop on the leaves and ultimately the leaves dry off and the young seedlings may perish. Young leaves are more susceptible to leaf spot incidence. Seedlings develop tolerance, as they grow old.

Management:

Prophylactic spraying with fungicides such as Difoltan or Foltaf (captafol) 0.2% or with Dithane M-45 (mancozeb) or Indofil M 45 0.3% may be given on the leaves. First spray is to be given during March-April depending on the receipt of summer showers and subsequent sprays at fortnightly intervals. Two to three rounds of spraying may be given. Clipping and destruction of severely affected leaves after spraying is to be done.

In addition to fungicidal sprays, the following supplementary measures also may be followed:

a) Sow the seeds in August-September, to ensure sufficient growth of seedlings, so that they may develop sufficient tolerance.

b) Avoid exposure to direct sunlight from top or sides. Use coir matting or coconut fronds for shade. When jungle leaves are used for thatching, sloppy roofing may be provided.

c) Do not raise the nursery continuously in the same site.

In grown up seedlings of the secondary nursery, another type of leaf spot is of common occurrence. Symptoms are yellowish to reddish brown rectangular patches seen on the lamina. These will be almost parallel to the side veins. The mature lesions show a muddy red colour. Following heavy infection, the leaves dry off. The disease is caused by the fungus Cercospora sp. The fungicides listed above can be used for controlling the disease.

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Nursery leaf rot

This disease is seen in young seedlings of 3-4 months old. It is not wide spread in occurrence; but seen only in a few nurseries. The symptom is development of water soaked lesions on the leaves, which later become necrotic patches leading to decay of affected areas. Usually the leaf tip and distal portion is damaged. In severe cases, rotting extends to petiole and leaf sheaths. It is caused by fungi such as Fusarium sp. Alternaria sp. etc.

Management:

To control this disease avoid excessive watering of seedlings. Spray 0.3% Dithane M45 (mancozeb) twice at 15 days interval after destroying the infected leaf portions.

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Damping off or seedling rot

The disease appears usually in the germination nursery (primary nursery) during rainy season when there is excessive soil moisture due to improper drainage. Leaves turn pale and their tips become yellow. Gradually, these symptoms spread over the entire leaf extending to leaf sheath resulting in wilting of seedlings. The collar portion decays and the entire seedlings die. Infection spreads in the nursery beds resulting in death of seedlings in small patches. In grown up seedlings, rotting extends from the collar region to the rhizomes resulting in their decay and ultimate death of the plant. Disease is caused by soil borne fungi such as Pythium vexans and Rhizoctonia solani . Fusarium oxysporum also causes similar seedling rot resulting in the wilting of the entire seedlings.

Management :

a) In the primary nursery, practise thin sowing for avoiding overcrowding of seedlings.

b) Provide adequate drainage facilities.

c) Remove affected seedlings early and maintain proper phytosanitary measures in the nursery.

d) Treat the nursery beds with formalin (formaldehyde 2%) for three days at the rate of 15 litres per square metre at least 15 days prior to sowing.

e) When infection is noticed, drench the nursery beds with copper oxychloride 0.3%

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Clump rot (Rhizome rot)

This disease occurs in mature seedlings (6 to 18 months old) of the secondary nursery. It is seen during the monsoon season when soil moisture is in excess due to improper drainage.

Early symptoms on leaves appear as pale yellow colour, partial rolling of leaf margins and withering of seedlings. Rotting or decay starts at the collar region and it spreads to rhizomes and roots. In severe cases, the collar region breaks off and the seedling collapses. The disease is caused by the soil-borne fungi Pythium vexans and Rhizoctonia solani . Rotting of roots due to Fusarium sp. is also observed.

Management:

a) Uproot and destroy all the affected seedlings in a nursery.

b) Stop irrigation of nursery beds.

c) Remove mulch materials from nursery beds and rake the soil gently.

d) Drench the nursery beds with copper oxychloride (COC) 0.3% at the rate of 3 to 5 litres per square metre. Two to three rounds may be applied at 15 days interval.