1.Cardamom thrips ( Sciothrips cardamomi )

•  Most destructive and persistent pest of cardamom.

•  They colonize and breed in different parts of the plant such as unopened leaves, spindles, leaf sheaths, flower bracts, perianths and flower tubes.

•  Adults and nymphs of the insect cause damage to panicles, flowers and capsules. It lacerates the surface tissues with mandibles and sucks the exuding plant sap by applying its mouth cone.

•  Injury to panicles results in its stunted growth, that on flowers leads to flower dropping and the injury produced on tender capsules develop as scabby growth on capsules as they mature. Affected capsules appear malformed, shrivelled and sometimes with gaping slits. Such capsules are inferior in aroma, have less number of seeds, and seeds are underdeveloped and may not germinate.

•  Thrips affected capsules fetch very low price in the market. Thrips infestation results in nearly 47% crop loss.

•  Adult insect is greyish brown, 1.25 to 1.5 mm long and with two pairs of fringed wings. Adults lay minute kidney-shaped eggs, which hatch out into nymphs in 12 days. Nymphs grow by feeding on plant sap and after passing through three larval and a pupal stage become adults, thus completing their life cycle in 21-32 days.

•  Population of the pest is maximum in summer (February-May), minimum in rainy period (June-July) and low in August-December.

Management:

1. Removal of collateral host plants of thrips, such as, Panicum longipes , Amomum sp., Aframomum sp., Colocasia sp., Alocasia sp., etc.

2. Remove dry drooping leaves, dry leaf sheaths, old panicles and other dry plant parts immediately before the commencement of first application of insecticide.

3. Apply any one of the recommended insecticides at the specified time as given below:

Insecticides recommended for thrips control (SP/EC formulations)

Insecticide

Strength (%)

Qty. (ml/g) of insecticide
per 100 litre water (High volume sprayer)

Quinalphos

0.025

100.0

Fenthion

0.05

62.5

Phosalone

0.07

200.0

Chlorpyrifos

0.05

250.0

Dimethoate

0.05

167.5

Acephate SP

0.075

100.0

4. During peak flowering periods, insecticide thart is less toxic to honey bees (phosalone) may be sprayed.

5. If water scarcity is felt during summer months, any of the following dust formulations may be applied.

Dust formulations

Chemical

Qty/ha

Methyl parathion

25 kg

Quinalphos

25 kg

Phenthoate

25 kg

Phosalone

25 kg

6. Recommended tentative schedule of insecticide application for Kerala, Tamil Nadu and Karnataka is given below.

A. Kerala

1. February
2. March
3. April
4. May

Once in 30 days

5. August
6. September
7. October to November

Once in 40 days

B. Tamil Nadu

1. December to January
2. March to April
3. May to June
4. August to October

C. Karnataka

1. January
2. March
3. May
4. September to October

7. Evaluation of products against thrips revealed that Neemmark15G and Nimbecidine were at par with monocrotophos in reducing the thrips damage

2. Borers

2. (a) Shoot/panicle/capsule borer [ Conogethes punctiferalis (Guen .)]

Infestation of borers on shoot, panicle and capsule is a serious problem to cardamom growers of Kerala, Tamil Nadu and Karnataka. The pest is larva of the lepidopteran Conogethes ( Dichocrocis ) punctiferalis (Guen.). Adult is a medium sized yellow moth with a number of black dots on its wings and abdomen. After a pre-oviposition period of 3-4 days, the moths lay eggs mostly on leaves or leaf axils of young pseudostem. After an incubation period of 5-6 days, the eggs hatch. Emerging larvae bore into tender panicles or unopened leaf spindle or immature capsule. At a later stage the larvae bore into the shoots. They feed the central core of the pseudostem resulting in decaying of the central spindle and the characteristic dead-heart symptom develops. When panicles and spikes are attacked, further production of flowers on them is stopped and the portion ahead of the site of entry dries off. In case of the capsules, the larvae feed on the seeds and the capsules become empty. A fully-grown larva is 15-25 mm long with pale purple body and black head. Larval period is completed within 28-36 days with five larval instars. After a pre-pupal period of 2-4 days, it becomes pupa. After 11-15 days of pupal period, adult emerges out through the borehole. The entire life cycle is completed within 41-51 days.

Management:

Pest infestation is pronounced in three seasons January to February, June, and September to October. Late stages of the larvae bore into pseudostem and remain there. Insecticide sprays at this time may not give adequate control of the pest. For an effective management of the pest, the insecticide has to be targeted on early stages of the larvae, which are usually present within 15-20 days after adult emergence in the field. Injection of the insecticide solution through the borehole is the alternate method for controlling larvae in pseudostem.Chemicals like Quinalphos and Dimethoate @ 0.05% are recommended.

2. (b) Early capsule borer ( Jamides alecto )

It is a serious pest of cardamom in Karnataka regions. Caterpillars of this insect bore and feed flower buds, flowers and capsules. The attacked capsules are completely emptied leaving a circular hole on the capsule, which eventually turn yellowish brown, decay and drop off in rainy season. The pest incidence is high during June to September.

Adult is a medium sized butterfly. Wings are bluish with metallic lusture on the upper surface. Larval period lasts for 18-20 days. Each larva feeds on 25-27 capsules to attain maturity. Pupation takes place in debris near the inflorescence. The life cycle is completed within 3845 days.

Management:

Removal of old panicles at the last harvest.

3. Cardamom whitefly ( Kanakarajiella [Dialeurodes] cardamomi )

Whitefly was considered as a minor pest in the early eighties. Of late, infestation of the pest has become severe and alarming in certain cardamom growing tracts of Kerala. The adult is a small soft bodied insect about 2 mm long and having two pairs of white wings. Adults are not active fliers, but can fly short distances. Female lays eggs, which are inserted in to the leaf tissue. Eggs are cylindrical, pale yellow when freshly laid and gradually turn brown. There are four nymphal stages. The first instar larva crawls on the leaf and finds out a feeding site. It becomes incapable of further movement from that place and all the later stages are completed at that spot. 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. Puparia which adhere to the leaves after emergence of adults appear as scaly patches on lower surface of affected leaves. The life cycle is completed within 2-3 weeks depending on weather conditions.

Management:

The flies are attracted towards yellow colour. This behaviour can be exploited to trap the flies on yellow sticky traps. Metal sheets painted yellow and coated with sticky materials, such as castor oil or polyvinyl butanol would serve as sticky traps. By placing such yellow sticky traps between rows of cardamom plants, population of adults can be monitored and trapped to some extent. Nymphs are effectively controlled by spraying on lower surface of leaves a mixture of neem oil (500 ml) and Triton (500 ml) in 100 litres of water. Acephate 0. 0.1 % is effective. The spray may be repeated two or three times at 15 days interval.

4. Root grub ( Basilepta fulvicorne )

( Refer Pests in Nursery )

5. Hairy caterpillars

They are group of defoliators of cardamom and are polyphagous. Eight species of hairy caterpillars have been found to damage cardamom plants. More destructive among them are Eupterote undata , E. fabia , E. cardamomi , E. canairica, E. mollis and E. blanda . They occur sporadically and congregate on trunks of shade trees. Moths emerge in June-July and lay about 300-800 eggs on the undersurface of leaves of shade trees. Eggs hatch in 15-25 days. Larval stages extend up to three months and the pupal period for nearly three months. When the north-eastern monsoon ceases, caterpillars drop down to cardamom and start feeding on its leaves. Larvae make cocoons within which they pupate.

Management:

Larvae can be collected and destroyed. Since they congregate on tree trunks, mechanical control is easy. If severe defoliation is noticed, spray chlorpyrifos 0.06%.

6. Shoot fly ( Formosina flavipes )

( Refer Pests in Nursery )

7. Lacewing bug (Stephanitis typicus)

It is a polyphagous pest, gregarious in habit. Nymphs and adults are found on lower surface of leaves. They suck the cell sap from leaves, and later greyish yellow spots develop on leaves. In case of severe infestation, plant growth is retarded and yield is adversely affected. Adult is a small dull coloured bug with transparent lacewings. A female lays about 30 eggs, which hatch in about 12 days. Nymphal period lasts for 13 days. Damage is very severe in summer months.

Management:

Destruction of alternate host plants like banana, Colocasia sp. and spraying of insecticides recommended for thrips control may be adopted for its management

8. Spotted red spider mites

(Refer Pests in Nursery )

9. Nematodes

(Refer Pests in Nursery )

10.Rodents & birds

Damage by rodents and birds could be considerably minimised by adopting trapping, clean cultivation, timely harvests and by baiting with bromodiolone (0.005%) or Rodafarin cake

Bee and insecticide management in cardamom plantation

Cardamom flower is bisexual. The most conspicuous feature of the flower is the large white labellum with violet streaks, which attracts insect for pollination. The essential floral part – stigma, is placed at a higher level by a slender style. Anther is situated well below the stigma. The flower thus represents a pin flower, which is best adapted to cross-pollination by an insect pollinator. Flower opening in cardamom is maximum between 5 a.m. and 7 a.m. Stigma receptivity and pollen viability are maximum during morning hours.

The honeybees Apis cerana indica and Apis dorsata are the major pollinators of cardamom flowers. Fruit setting increases significantly in bee-pollinated flowers compared to flowers prevented from bee-pollination. Bees start foraging in morning hours and it is high between 7 a.m. and 11 a.m. During misty days, the forage is delayed for an hour or two. A bee usually visits all flowers in a clump and crawl over the anther and stigma. During this process it carries anther from one flower and a part of it gets deposited on the stigma of another flower. For effective pollination in cardamom, four bee colonies per hectare are required. Studies have indicated that an increase in yield up to nine per cent could be obtained by keeping two to three bee boxes per

ha of cardamom. Since bees are highly sensitive to insecticides, certain precautions may be taken to prevent their destruction by insecticides:

1. Dust formulation, which are more harmful to honey bees than other formulations of insecticides, shall be applied only in times of acute water shortage.

2. Insecticide sprays shall be done in afternoon.

3. Insecticides less toxic to bees may be selected for spraying during peak flowering periods.

4. In the evening, previous to the day of insecticide application, beehives may be closed and covered with wet gunny bags after providing sufficient sugar solution and water in the hives. The hives may be opened on the next day morning.

Diseases

1. 'Katte' (Mosaic) disease

The disease is prevalent in all cardamom growing areas in India. It is one of the major diseases of cardamom. 'Katte' disease affects plants of all ages. The first visible symptom appear on the youngest leaf of affected tillers as spindle shaped chlorotic flecks. Later, these flecks develop into slender discontinuous stripes of pale green and dark green areas, running parallel to the veins from the midrib of leaf margin. As the disease advances, subsequent leaves show characteristic mosaic symptoms. The leaf sheaths and pseudostems also show mosaic pattern. Mature leaves formed before infection do not develop symptoms. The infection is systemic in nature and gradually spreads to all tillers of affected plant. Immediately after infection, there is no growth reduction but within one to two years after infection, there is a gradual reduction in clump size. In advanced stages, the affected plants produce shorter and slender tillers with a few shorter panicles. 'Katte' affected plants do not die but the plants give only poor yield. The yield reduction has been found to be 70 per cent within three years after infection.

The disease is systemic and it is caused by cardamom mosaic virus. Viral particles are present in all parts of affected plants except in mature seeds. The disease is not transmitted through seeds or by mechanical means either by contact or through cutting tools. The disease is transmitted by insect vectors. The common banana aphid Pentalonia nigronervosa Coq. spreads katte disease from infected to healthy plants by feeding. Even a single aphid can pick up and transmit the virus within a few minutes without incubation period in the vector. All stages of the vector viz., the nymphs, winged and non-winged forms of adults can transmit the disease.

Man acts as the main carrier of the disease over long distances by unknowingly transporting the diseased materials for planting. Once the disease enters a plantation the spread is internal through the vector. Disease incubation period (time required for symptom expression) in the plant varies from 35 to 120 days in different months. Usually during summer, delayed appearance of symptoms is noticed. Vector population is high from December to May.

Management:

As long as katte inoculum is present in the field, any formulation of insecticides fails to prevent the disease spread. Diseased plants cannot be cured but the losses can be minimized by adopting the following measures:

a) Keep a constant surveillance on the occurrence of katte disease.

b) Use only healthy seedlings raised from 'katte' free plants.

c) Avoid rhizome planting using materials taken from disease-affectedsgardens.

d) Practise regular roguing (uproot and destroy).

e) Repeat tracing of affected plants and roguing at weekly intervals for at least four consecutive months.

f) Replant the rogued areas with healthy disease free materials.

g) Destroy wild plants like Amomum, Alpinia, Curcuma, Colocasia etc. if they show symptoms of katte.

h) Do not raise nursery near katte-affected areas.

2. Nilgiri necrosis disease

It is also another viral disease like 'katte'. It was recently observed in Nilgiri area and subsequently in Valparai in Anamalai, lower Pulneys and Munnar areas. As compared to 'katte' it is of limited occurrence.

Diseased plants show alternate light green and whitish to yellowish streaks on the leaves in the form of mosaic. Later these stripes become necrotic with reddish brown colour followed by tearing of lamina. The leaves are crinkled with wavy margin. The reddish brown necrotic areas later dry off. Tillers show reduction in height. In advanced stages of infection, severe stunting of plants is seen. Tillers are narrow, very short and they produce small leaves, which are brittle. Panicles become shorter with few reduced capsules, which often show symptoms of cracking. In extreme stages of disease no panicle is formed. The disease is caused by a rod shaped virus.

Like katte, it is a systemic disease. Nilgiri necrosis is not transmitted through seed or mechanical means but the disease is easily carried through infected rhizomes. So far, no insect vector is known to transmit the disease.

Management:

Plant sanitation by rouging of affected plants is the only method by which the disease can be controlled. The methods adopted for the control of katte can also be followed for managing Nilgiri necrosis disease.

3. Kokke kandu disease (Cardamom vein clearing)

Recently a new viral disease is found to be widely spreading in plantations of Karnataka state. In Kannada, it is called 'Kokke kandu' which means hooked tiller. It is first observed in Hongedehalla, which is the hot spot area of this disease. Later, it spread to Sirsi and Somawarpet areas.

Diseased plants show symptoms on the tillers and leaves. Characteristic mottling develops on the foliage which later show severe vein clearing. Yellow stripes or streaks run parallel to the side veins. Leaves are arranged in a rosette manner at the tip of the tiller with much reduced internodes. The tiller height is also reduced. In advanced stages of infection, tillers are stunted and their tips form hook like structures after the younger most leaf roll gets hooked up in the leaf sheaths. Panicle length and number of capsules are much reduced. In extreme stages, no panicles and capsules are produced and the yield loss is almost 100 per cent.

The disease spreads rapidly to nearby areas and the infected plants decline in a short period of one to two years. No seed or sap transmission is noticed. The disease spreads easily through infected rhizomes as in the case of katte disease. The banana aphid Pentalonia nigronervosa is found to be its natural vector. It transmits the disease in a non-persistant manner. There is no incubation period in the vector. About 30 to 40 days are required for the infected plants to show the symptoms. Sometimes combined transmission of 'katte' and 'kokke kandu' by the aphid is observed in the same plant. The disease is caused by cardamom vein clearing virus.

Management:

As it is a systemic viral disease, infected plants can never be cured. Plant sanitation is the only preventive measure. The methods recommended for katte control can be followed for management of kokke kandu disease also.

4. Azhukal or capsule rot disease

'Azhukal' disease is mostly prevalent in Idukki and Wayanad districts of Kerala. In recent years, it has been noticed in isolated pockets in Anamalai area also. Azhukal (rotting) is caused by the fungus Phytophthora meadii . The disease starts with the onset of southwest monsoon in June and becomes severe during July-August months. It may continue to prevail up to November-December, if weather is favourable for disease development.

Symptoms of rotting appear on all plant parts. First symptoms appear on the young leaves or on capsules in the form of water soaked lesions. In leaves, these areas enlarge, become necrotic and gradually the leaves shrivel and begin to shred. Finally, the affected leaves break at the base of the petiole and remain hanging. Rot affects the capsules of all ages. Affected immature capsules soon decay and fall off within 3 to 5 days and mature capsules get shrivelled on drying. Infection on the panicle appears usually on panicle tip and proceeds downwards. Such portions later dry off or decay if moisture is in excess. In severe cases, infection spreads over to the rhizomes and tillers also. Decayed tillers break and fall off at the collar region. All the varieties are susceptible to the disease. However, Malabar variety is more severely affected due to this disease. The disease spreads through soil, water and wind.

The predisposing factors favouring 'azhukal' incidence are heavy and continuous rainfall, excess soil moisture, thick shade, overcrowding of plants and prevalence of inoculum in the soil.

Management:

a) Phytosanitation

i) Trashing and cleaning the plant base are to be carried out during May before the onset of monsoon.

ii) Thick shade may be regulated by gentle lopping of tree branches.

iii) Provide drainage in low-lying and marshy areas.

iv) Destroy the azhukal affected portions and plant debris.

b) Fungicidal applications: After completing the above mentioned plant sanitation measures, the plants may be sprayed with any one of the following fungicides.

i) Bordeaux mixture 1%  

The first spray should be done during May-June before the onset of the monsoon and a subsequent spray may be done during July-August. A third spray may be given in the month of September if the monsoon is prolonged and disease is still persistent.

Spray Bordeaux mixture on the entire portion of the plants at the rate of 500 ml to one litre per plant. Two to three litres of Bordeaux mixture drenching at the plant base is to be done in areas where azhukal is severe. Alternatively, drenching plant base with COC (0.25%) was found to be effective in reducing soil inoculum and further disease spread. For easy percolation to deep soil layers, COC drenching is found to be superior to Bordeaux mixture drenching.

Drench with Fosetyl –Al (3-5 l/plant)  and repeat this at monthly interval depending the intensity of the disease and rainfall.

5. Clump rot or rhizome rot

If is also a fungal disease occurring during the monsoon season. Symptoms of disease are yellowing of leaves and decay of tillers starting from the collar region. The decay extends to the rhizomes and roots also. Rotten rhizomes become soft, dark brown coloured and ultimately result in the total death of the plant. Affected tillers fall off by a slight disturbance. The disease is caused by soil-borne fungi such as Pythium vexans , Rhizoctonia solani and Fusarium sp. (in a few cases). In some cases, a pink colour develops at the collar region, which later leads to rotting.

Management:

a) Plant sanitation as described in the case of azhukal disease has to be followed to control this disease.

b) The plant base is to be drenched with 2-3 litres of COC (0.25%). Repeat COC drenching at 30 days intervals for 2 to 3 times at monthly intervals.

As a boicontrol measure, inoculate suckers with native arbuscular mycorrhiza, Trichoderma and Pseudomonas at the time of planting and apply during pre-monsoon period in established plantations

General recommendations:

1. Plant protection measures are to be carried out on priority basis.

2. Diseased areas should be taken first for trashing and spraying with fungicides.

3. Spraying should be done covering the diseased portions.

4. When the plants are wet during raining, foliar spray may not be effective. Practise soil drenching in such situations.

5. Top preference may be given for fungicidal sprays during non-rainy days.

Biocontrol of rot diseases:

Recent studies show that azhukal and rhizome rot can be controlled to some extent with the bio-agent Trichoderma . It is antagonistic soil fungus acting against the rot pathogens. The fungus is green in colour and grows abundantly on cowdung and organic crop residues such as coffee husk, tea waste, neem cake, coir compost etc. Trichoderma viride or T. harzianum specific to cardamom can be mass multiplied on carrier media for 30 to 45 days. These can be applied to plant basins at the rate of 1 kg per 5 kg of cowdung during May, August, September and October months after phytosanitation.

While Trichoderma is applied in the soil, no fungicide should be drenched in the soil. However Bordeaux mixture can be sprayed before the application of Trichoderma . If the soil is drenched with COC or other fungicides, Trichoderma should be applied only after one month.

In severely diseased areas, first one or two rounds of fungicides can be applied. One month after this, Trichoderma can be used. But never use fungicides and Trichoderma together.

Minor diseases

a. Chenthal

The disease is seen in almost all areas of cardamom cultivation. Initial symptoms appear as water soaked lesions on young leaves. Later these become yellowish to reddish brown with a pale yellow halo. In severe cases, it leads to the withering of leaves and withering of psuedostems. The disease intensity is found to be severe in open areas where shade is inadequate. 'Chenthal' was reported to be caused by Corynebacterium sp. However, latest studies showed that it is not a bacterial disease. It is caused by a fungus called Colletotrichum gloeosporioides.

Management:

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

b. Leaf blotch

It is caused by the fungus Phaeodactylium venkatesanum.  Symptoms develop as dark brown blotches on the leaves during monsoon season. Later, on the under side of these blotches, the fungal mycelium and spores develop as grey brown masses.

Management:

The disease can be controlled by one to three rounds of spraying with carbendazim (1 g/litre) , or Bordeaux mixture 1% or mancozeb (Dithane M-45) 0.3%.

c. Leaf spots and leaf rusts

Various types of leaf spots are found to affect the leaves. These are Sphaceloma leaf spot caused by Sphaceloma cardamomi , Cercospora leaf spot caused by Cercospora zingiberi and leaf rust caused by Phakospora elettariae.

The Sphaceloma leaf spot is seen in main plantation as scattered spherical blotches on the leaves. These start as small spots measuring a few mm and later several spots coalese to form larger areas.

The Cercospora leaf spots are found in the nursery and plantations in the form of rectangular muddy red stripes running along the veins.

Leaf rust is often seen on mature leaves as whitish powdery pustules on the under surface of the leaves with corresponding yellow necrotic patches on the upper surface. Diseased leaves show a rusty appearance.

Management:

The leaf spots can be reduced to some extent by spraying with fungicides such as Dithane M-45 (0.25%) or bavistin (0.2%). For leaf rust, so far no effective fungicide was found.

d. Capsule canker and capsule brown spots

Canker like symptoms and capsules were often observed as glazy discoloured erruptions on the capsule rind. On curing, these spots turn greyish to dull white raised blisters on the capsule surface. The etiology is not yet known.

The capsule brown spot, also called as anthracnose disease, is caused by the fungus Colletotrichum gloeosporioides . Disease symptoms appear as small round reddish brown lesions on the pericarp of the capsule. On maturation, these spots become soft reddish sunken areas. On cured capsules also the spots retain their red colour.

e. Leaf blight

Leaf blight or drying of leaves in patches is observed during October to February months. In areas covered by severe fog the severity is more. Brown dry areas of varying sizes develop on the lamina. It is caused by Phytophthora meadii .

Management:

It can be controlled by one or two rounds of spraying with 1% Bordeaux mixture or 0.3% aliette or 0.4% akomin.

One to two rounds of sprays with bavistin (0.2%) or Dithane M 45 (0.2%) reduces further disease spread.

Preparation of Bordeaux mixture:

Dissolve 1 kg of copper sulphate in 10 litres of water.

In another vessel, slake 1 kg of quicklime by adding small quantity of water preferably warm water (Up to 1.25 kg of lime can be taken if the lime is not of good quality). When slaking is over, add 5 litres of water and stir well to get a uniform suspension of lime. Transfer the lime suspension thus prepared through a sieve to a vessel containing 85 litres of water and stir well. A small quantity of lime solution may be kept separately.

Add 10 litres of the copper sulphate solution to the 90 litres of lime solution with constant stirring. To test the correctness of the mixture, dip a brightened iron knife for a minute in the mixture. If the knife remains bright, the mixture is correctly prepared. If the knife turns rusty brown or if its brightness is lost, add more lime suspension. Correctly prepared Bordeaux mixture will turn red litmus to blue and turmeric powder to orange red in colour.

Important points:

1. For dissolving copper sulphate for Bordeaux mixture, use copper, wooden, earthen or plastic containers.

2. Use fresh quicklime.

3. Bordeaux mixture should be passed through a sieve before transferring to the sprayers.

4. Spraying of Bordeaux mixture should be done on the same day of preparation.