CROP HUSBANDRY-CARDAMOM CULTIVATION PRACTICES IN KERALA

CARDAMOM (Elettaria cardamomum)

The habitat of small cardamom is the evergreen forests of Western Ghats. It is grown in areas where the annual rainfall ranges from 1500-4000 mm with a temperature range of 10-35 ºC and an altitude of 600-1200 m above MSL.

Cardamom is generally grown in forest loam soils rich in available phosphorus and potassium. The crop is raised mainly on well drained, deep, good textured soils rich in humus.

Varieties
ICRI-1, ICRI-2, PV-1 and PV-2.

Cultivars
Malabar: Suitable for areas from 600 to 1200 m elevation
Mysore: Suitable for areas from 900 to 1200 m elevation
Vazhukka: Suitable for areas from 900 to 1200 m elevation

Propagation
Cardamom can be propagated vegetatively and by seedlings. For vegetative propagation, rhizomes with not less than three shoots are used. Plants propagated vegetatively come to bearing one year earlier than the seedling-propagated plants. But this method has the disadvantage of spreading the `katte' disease, which is of viral origin. This disease is not transmitted through seeds. Hence in areas where the disease is widespread, it would be safer to use seedlings for propagation.

Nursery
Ripe capsules of the desired cultivar are collected from high yielding plants during September-October. The seeds are extracted by gently pressing the capsules. In order to increase the germination percentage, seeds can be treated with concentrated sulfuric acid or nitric acid for not more than two minutes. The extracted seeds are washed in cold water four times to remove the mucilaginous coating. The washed seeds are drained and mixed with ash and allowed to dry in shade for 2 or 3 days. The seeds should be sown in the nursery within a fortnight. Sowing in September is the best for high germination. Sowing during southwest monsoon and winter should be avoided.

When it becomes necessary to store the seeds, it is advisable to store them in capsule form. It can be preserved in this form for one month, without deterioration of viability. Polythene lined gunny bags can be used for this.

In Kerala and Tamil Nadu, 18 month old seedlings are used for planting. The seeds are sown in primary nursery from where the young seedlings are transplanted to a secondary nursery and maintained for one year before planting in the main field.

Primary nursery
The nursery site is selected in open, well-drained areas, near a source of water. The land is dug to a depth of 30 cm, cleared of all stubbles and stones; and clods are broken. Beds of size 6 x 1 x 0.3 m are then prepared. Jungle soil is spread in a thin layer over the nursery bed. Seeds are sown on the bed in lines. For an area of 1 m2, 10 g of seed is required. Sixty grams of seeds will be required for a nursery bed of 6 m2. The seeds are covered with a very thin layer of fine soil. The nursery bed is mulched with dry grass. Potha grass (Grenetia stricta) commonly seen in high range areas is a suitable material for this purpose. Grass is spread to a thickness of about 2 cm. Paddy straw can also be used for mulching. After sowing, beds have to be watered every day in the morning and evening. The mulch should be removed on commencement of germination. The seedlings have to be protected by providing shade pandals. Regular watering, weeding and protection from pests and diseases are to be attended to. During June-July, seedlings from the primary nursery are transplanted to the secondary nursery.

Secondary nursery
After preparing the site properly, form nursery beds of 6 x 1 x 0.3 m. Mixing of well decomposed cattle manure and wood ash with the top layer of the soil will help the seedlings to establish well and to grow vigorously. During June-July, the seedlings from the primary nursery are transplanted at a spacing of 25-30 cm. Shade pandals should be provided before transplanting. Overhead pandals or individual pandals for each bed may be erected. Mulching the bed with dry leaves will help to conserve soil moisture. Regular watering during dry months, weeding, application of fertilizers, control of pests and diseases and mulching are the essential operations for the maintenance of the secondary nursery. One month before uprooting, the pandal should be removed to encourage better tillering.

Polybag nursery
Polybags can be used for raising secondary seedlings. For such nurseries, seeds are to be sown in beds in primary nurseries in September and transplanted to polybags in December-January. These seedlings would be ready for planting in June-July. In this case, nursery period could be reduced by 6 to 7 months.

Rhizome multiplication
This may be taken up from the first week of March to the first fortnight of October. The site is selected in open, gently slopping and well-drained areas near a source of water. Trenches of 45 cm width, 45 cm depth and convenient length are taken across the slope or along the contour 1.8 m apart. They are filled with equal quantity of humus rich topsoil, sand and cattle manure. Uproot a part of the high yielding disease free mother clump identified in the plantation. Trim the roots and separate the suckers so that the minimum planting unit consists of one grown up tiller and a growing young shoot. Plant them at a spacing of 1.80 m x 0.60 m in filled up trenches. Provide sufficient mulch and stake each planting unit. Provide overhead pandal as in the case of seedling nursery and remove shading material with onset of monsoon rains. Provide irrigation once in a fortnight and adopt necessary plant protection measures. Apply fertilizers @ 100:50:200 kg/ha N:P2O5:K2O in six splits at an interval of two months. Apply neem cake @ 100-150 g/plant along with fertilizers. On an average, 20 to 30 suckers / initial planting unit can be produced within one year of planting. Care should be taken to identify and collect mother clumps only from areas totally free from 'katte' disease.

Soil treatment in nursery
It is recommended that the primary and secondary nursery soil may be drenched with formalin 2% solution and covered with polythene sheets for 3 days. Planting should be taken up only 15 days after treatment to avoid phytotoxicity.

Control of pests and diseases in the nursery
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. Drenching the nursery beds with chlorpyrifos at 0.04% can control the pest.

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. Spraying of quinalphos 0.025% or application of phorate granules @ 1 g ai/m2 is recommended for the control of the pest.

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

Nematodes
Nematodes are observed as serious pests in cardamom nurseries. Roots of cardamom seedlings are infested mainly by root knot nematode (Meloidogyne incognita). Lesion nematodes (Pratylenchus) are also seen in cardamom roots and soils. The main symptoms of nematode infestation are galls on the root tips, profuse tillering, stunted and weak tillers, yellowing and drying of leaves and production of narrow, brittle and abnormal leaves. Treatment of soil as detailed above is an effective method to control nematode.

Fumigation of primary and secondary nursery beds with methyl bromide is another effective method for the control of nematodes in the nursery. Five hundred gram of methyl bromide is required for 10 m2 area. The treated area has to be kept covered with polythene sheet for two to three days. Pruning of infested roots tips before planting is also recommended.

Treat the plants in the nursery with carbofuran @ 5 kg ai/ha after 10 days of germination and this is repeated after 3 months. In secondary nurseries, the plants may be treated with carbofuran @ 10 kg ai/ha after transplanting and every three months thereafter.

Damping off
This disease is caused by Pythium vexans and Rhizoctonia solani. Infection is observed at the collar region. Provide good drainage, and spray and drench the nursery with 1% Bordeaux mixture or 0.2% copper oxychloride.

Nursery leaf spot
This disease is caused by Phyllosticta elettariae. Pale specks appear on the leaf lamina, which dry up and become paper white. Spraying the plants with mancozeb 0.25% at fortnightly intervals is effective in controlling the disease.

The other diseases are Sphaceloma leaf spot, Cercospora leaf spot, rust and sooty mould.

Main field planting
Cardamom plantation is raised in forests under the shade of tall trees. For raising a new cardamom plantation, the undergrowth of bushes is cleared. When open areas like marshy valleys and grasslands are selected for raising new plantation, shade trees have to be raised before planting cardamom seedlings. The quick growing shade trees like dadap (Erythrina lithosperma) is generally used for this purpose. Cuttings of this tree are used for planting. But this tree is a host of root knot nematode, which infests cardamom. Other quick growing trees like Albizia can also be used. Useful trees like jack and eucalyptus can be used along with red cedar, wild nutmeg, kurangatti etc.

Spacing

Mysore and Vazhukka: 2 x 2 m to 3 x 2 m depending on the fertility of the soil
Malabar: 1.5 x 1.5 m to 2 x 2 m depending on the fertility of the soil.

The recommended size of pits is 60 x 60 x 35 cm. The pits are filled with rich topsoil at least two months in advance of planting the seedlings. Application of well decomposed FYM or compost or leaf mould and 100 g of rock phosphate with the topsoil in the pit will help in proper establishment and quick growth of plants. If the selected site is a hill slope, terraces may be formed before digging pits.

Planting can be done with the commencement of southwest monsoon, before the heavy rains. A small pit may be formed inside the pit by scooping out soil at the centre of the pit for planting seedlings. The soil may be put just to cover the rhizomes. Care should be taken to ensure that the rhizomes do not go deep into the soil.

Cultural operations
A regular schedule of cultural practices consisting weeding, mulching, trashing, shade regulation, fertilizer application, irrigation, etc. will have to be undertaken.

Sufficient mulch should be applied at the base of the plant during December to reduce the ill effects of drought during summer months and to conserve soil moisture. Sickle weeding is essential which has to be carried out frequently depending upon the intensity of weeds. Forking is necessary in hard soils, which is to be carried out in October-November.

Trashing (removal of old and dried shoots, leaves and dried panicles) should be taken up once in a year during June-July, with the commencement of monsoon. This will help to prevent the spread of diseases and expose the panicles to easy visit by honeybees.
Soil conservation measures, maintenance of drainage channels and such other operations may be taken up promptly.

Manuring
Application of organic manures such as FYM, cowdung or compost @ 5 kg / plant or neem cake @ 1-2 kg / plant may be done during June-July. The present recommendation of nutrients for cardamom in Kerala is N:P2O5:K2O @ 75:75:150 kg/ha. The fertilizers may be applied in two split doses, before and after the southwest monsoon, in a circular band of 20 cm wide and 30-40 cm away from the base of the clumps, and mixed with soil.

Shade
Since inadequate as well as excessive levels of shade are harmful to the crop, regulation of shade is inevitable. There should be sufficient shade to protect cardamom plant during the hot season. By regulating the shade before the monsoon, more light becomes available to the plant during the rainy season. Red cedar or chandana-vempu (Toona ciliata) is an ideal shade tree. It sheds the leaves during rainy season and thus provides natural shade regulation. Some of the other shade trees are kurangatti (Acrocarpus fraxinifolius), vellakil (Dysoxylum malabaricum) and thelli (Canarium strictum).

Bee-keeping for better pollination
The main pollination agent in cardamom is honeybee (Apis cerana indica). Maintaining four bee colonies per hectare during the flowering season is recommended for increasing fruit set and production of capsules.

Harvesting and processing
Cardamom plants normally start bearing capsules from the third year of planting. Picking is carried out at an interval of 30 days. After harvest, cardamom capsules are processed.

Cardamom capsules with green colour fetch a premium price in foreign countries. Hence emphasis has to be given on the preservation of green colour during curing and subsequent storage. Capsule should be processed within 24-36 hours after harvest to prevent deterioration. By curing, the moisture of green cardamom is reduced to 8-12 per cent at an optimum temperature so as to retain its green colour to the maximum extent.

Harvesting season in Kerala is October-February and the peak period of harvest is September-November.

Sun-drying
Capsules are dried directly under sunlight for five to six days or more. Frequent turning is done. This method can result in surface blemishes and may not give an attractive green colour. This method is practiced if the cultivar yields fruits that turn yellow before they are ready for picking and where facilities for green curing are not available.

Artificial drying
Processing of capsules is done in specially built curing houses. The harvested capsules are washed in water to remove dust and soil particles. Then they are spread on wire net trays in curing chamber. Burning firewood in the iron kiln produces heat required for drying. The heat thus produced is passed through pipes made of galvanized iron sheets. The process of drying takes about 18-24 hours, depending on the ambient temperature. The capsules are spread thinly in the wire net trays and stirred frequently to ensure uniform drying. They are initially heated at 50 ºC for the first 4 hours and heat is then reduced to 45 ºC by opening ventilators and operating exhaust fans till the capsules are properly dried. Finally the temperature is raised to 60 ºC for an hour.

The dried capsules are rubbed on wire mesh to remove the stalk and dried portion of flower from the capsules and then graded according to size by passing through sieves of sizes of 7, 6.5, 6 mm etc. The graded produce is stored in polythene lined gunny bags to retain the green colour during storage and also to avoid exposure to moisture.

A relatively new innovation in the curing procedure is blanching by soaking the fruits in 2.0 per cent washing soda for 10 minutes prior to drying. This inhibits colour loss during drying operation and extends colour retention during subsequent storage from three months to ten months.

Bleaching
A proportion of the crop is bleached after sun drying by exposing the capsules to fumes from burning sulphur to get uniform colour and appearance. Steeping capsules in a dilute solution of potassium metabisulphite solution induces a slight improvement in keeping quality.

Oleoresin
Solvent extraction of ground spice yields 10 per cent oleoresin. Cardamom oleoresin is used for flavouring food after being dispersed in salt, flour etc. One kilogram of oleoresin replaces 20 kg ground spice.

Decorticated seeds / seed powder
Decorticated seeds command a lower price due to rapid loss of volatile oil during storage and transportation. Seed powder is marketed to a limited extent.

Control of pests and diseases in the plantation

Cardamom thrips (Sciothrips cardamomi)
This insect is a serious pest of cardamom. It colonizes and breeds in unopened leaves, leaf sheath, flower bracts and flower tubes. It lacerates and feeds on the exuding sap from the aerial parts. Infestation on the panicle and flower buds results in stunted growth of panicles, shedding of flower buds and warty growth on the surviving capsules. The infested capsules are light in weight, inferior in quality and fetch very low price in the market. Since the pest population is high during dry months from December to May, pesticide application during this period is important. Four sprayings or dusting of insecticide during this period is recommended. Insecticide application can be skipped during rainy months of June and July. Three more sprayings are to be given during the period from August-November. Any of the following insecticides are recommended for thrips control.

EC formulations: Quinalphos 0.025%, fenthion 0.03%, phenthoate 0.03%, phosalone 0.05%, monocrotophos 0.025%, fenitrothion 0.05%, formothion 0.03%, dimethoate 0.05%.

Dust formulation: Quinalphos 1.5%, carbaryl 10%, phosalone 4% or phenthoate 4% each at 25 kg/ha

Shoot/capsule borer (Conogethes punctiferalis)
It is a serious problem to cardamom growers of Kerala, Tamil Nadu and Karnataka. At the early stage of the crop, the caterpillars of this yellow coloured moth bore into the core of the aerial stem resulting in the death of central spindle, which appears as characteristic dead hearts.

At the time of flowering, when the caterpillars attack the panicles and spikes it may lead to flower shedding and drying up of the attacked portions. At a later stage of the crop, the caterpillars bore into the capsules, feed on the seeds and make them hollow. The presence of excreta at the region of attack indicates presence of the caterpillars in the pseudostem, inflorescence and pods.

Pest infestation is pronounced in three seasons viz. January-February, June and September-October.

Control

Late stages of larvae bore into the pseudostem and remain there. Insecticides sprayed at this time may not give adequate control of the pest. For an effective management of the pest, the insecticides have to be targeted on early stages of the larvae, which are usually present within 15-20 days after adult emergence in the field. Spraying fenthion 0.05% or monocrotophos 0.05% is recommended during the months of February-March and September-October.

Leaf eating caterpillars
There are 10 species of caterpillars feeding on cardamom leaves. Out of these, seven species are hairy and appear in large numbers during certain seasons causing extensive defoliation. For controlling the leaf caterpillars, mechanical collection and destruction and spraying of any contact insecticide are recommended.

Cardamom whitefly (Kanakarajiella [Dialeurodes] cardamomi)
It is a serious pest in cardamom growing tracts of Kerala. The adult is a small soft-bodied insect, about 2 mm long and having two pairs of white wings. The nymphs are elliptical and pale green. The nymphs secrete sticky honeydew, which drops on to lower leaves. On these, black sooty mould develops, which interrupts photosynthesis of the leaves.

Control

The flies are attracted towards yellow colour. So metal sheets painted yellow and coated with sticky materials, such as castor oil or poly-venyl butanol would serve as traps. By placing such yellow sticky traps between rows of cardamom plants, population of adults can be monitored and adults trapped to some extent. Nymphs are effectively controlled by spraying the lower surface of leaves with a mixture of neem oil (500 ml) and triton (500 ml) in 100 litre of water. Acephate 0.075% and triazophos 0.04% are equally effective. The spray may be repeated two or three times at 15 days interval.

Cardamom root grubs (Basilepta fulvicorne)
The grubs of a small, greenish blue beetle cause damage. The grubs are short, stout, pale white in colour and often assume a shape resembling 'C', which feeds on cardamom roots. The symptoms start as yellowing of leaves, which later result in the drying up and death of the plant

Control

Collect the beetle with hand nets or sticky traps at the time of mass emergence (March-April and August-September) and destroy. Early stages of the grub which are usually present in soil during May-June and September-October can be controlled either by drenching chlorpyriphos 0.04% @ 3-4 litre per clump or by applying phorate @ 2-4 g ai/ha 10-15 cm around the plant.

Cardamom scale (Aulacaspis sp.)
This scale insect is found on the lower surface of leaves, leaf sheath, panicles and fruit stalk. As a result of damage, capsules get shrivelled, panicles become dry and the leaves become yellow. The pest is mostly seen during summer months.

Control

Spray monocrotophos or fenthion @ 0.05 % during the peak season.

Nematodes (Meloidogyne sp.)
Root knot nematodes are the most common nematode species associated with cardamom plantations. Common symptoms are necrosis of leaf tips and margins, narrowing of leaves, thickening of veins, reduction of internodal length and consequent appearance of leaves as rosette. Roots branch heavily and galls appear on them. Plant becomes highly stunted.

Control

Frequent change of nursery beds will help to reduce nematode infection in nurseries. In case of infection in primary nurseries, application of carbofuran @ 80 g per 6 m2 bed and in secondary nurseries, application of carbofuran @ 200 g / 6 m2 bed will control the pest. In plantation, carbofuran @ 60-80 g/plant or 20-40 g of phorate with 300-500 g of neem cake per plant may be applied. Application may be repeated after three months.

Diseases
Katte or mosaic
This is a virus disease, which is transmitted by the banana aphid, Pentalonia nigronervosa. The symptoms consist of discontinuous stripes of light green colour running almost parallel to each other from the mid-rib to the margin of the leaves, which form a mosaic pattern. On young shoots, such stripes are seen on the leaf sheath also. The infected clumps will be smaller in size with fewer tillers.

Control

Eradication of the source of inoculum by destroying infected plants and destruction of the vector by insecticide application are effective. Regular application of insecticide against cardamom thrips controls the aphids also. Avoid using katte-infected rhizome for planting.

Destruction of plants showing symptoms of the disease should be done promptly once in two months. Removal of all alternate hosts of virus is also recommended.

Azhukal
This is a fungal disease caused by Phytophthora sp. occurring during the rainy season. It affects the leaves, tender shoots, panicles and capsules. On the infected leaves, water soaked lesions appear first and rotting and shedding of leaves along the veins occur thereafter. The infected capsules become dull greenish brown and decay. This emits a foul smell and subsequently shed. Infection spreads to the panicles also.

Control

Trashing and destruction of the infected parts should be done as a phytosanitary measure just prior to the onset of southwest monsoon. Remove the trash (dried leaves and leaf sheaths) from the basal region of the plant to the extent possible.
Spray the shoots with 1% Bordeaux mixture with adhesive (rosin soda or any other sticker) by the commencement of the monsoon and continue the spraying operation two or three times up to November-December according to the intensity of the disease and rainfall. Give a copious spray to the panicle with 1% Bordeaux mixture @ 3 l/plant during July-August when the disease intensity is maximum.

Trichoderma can be used along with cowdung for controlling this disease.

Clump rot or rhizome rot
This disease is caused by Pythium aphanidermatum, P. vexans, Rhizoctonia solani and Fusarium oxysporum. The affected shoots become brittle and easily break off from the rhizome at the bulbous base.

Control

Drench with 0.2% copper oxychloride (2-3 litre per plant) and repeat this two times at monthly intervals.

As a bio-control measure, inoculate seedlings with native arbuscular mycorrhiza, Trichoderma and Pseudomonas fluorescens at the time of planting in the nursery and main field, and apply during pre-monsoon period in established plantations (see the chapter on biocontrol agents against plant pathogens).

Leaf blotch disease

The fungus Phaeodactylium venkatesanum causes this disease. The disease is characterized by the appearance of large blotches of irregular lesions with alternating shades of light and dark brown necrotic tissues. This is mainly observed on mature leaves. On the lower surface of the lesions ash coloured white superficial growth of the fungus appears during moist weather conditions.

Control

The fungicides, Bordeaux mixture (1%), mancozeb (0.3%) and carbendazim (0.1%) are effective in controlling the disease.

Chenthal disease
Chenthal disease is characterized by the appearance of rectangular linear reddish brown lesions mainly on the lower surface of the leaves. The lesions are clearly visible even on dried leaves. The incidence of the disease appears to be more severe in areas, which do not have proper shade. Even though Corynebacterium and Colletotrichum gloeosporioides have been isolated from the infected leaves, the pathogenicity of these organisms could not be established.

Control

Providing adequate shade is the only measure recommended pending confirmation of etiology of the disease.

Waiting period of insecticide / fungicide
Quinalphos 30 days
Monocrotophos 30 days
Mancozeb 30 days