Scientific name: Areca catechu Common name: Khasi: Kwai; Hindi:  Betel nut or supari

Composition & Uses

Chemical composition of marketed arecanut depends on maturity of the nuts, since processed arecanuts are made from both green and ripe nuts. The major constituents are Polyphenols, fat, polysaccharides, fibre and protein.Alkaloid, arecoline, is present as a minor but significant constituent.Polyphenol content decreases with increasing maturity, hence tender nuts have better protection from infection compared to ripe nuts. The hardening of nuts during maturity is due to formation of polysaccharides.

Arecanut (Areca catechu), popularly known as betel nut or supari, is the source of common masticatory. As an essential requisite for several religious and social ceremonies in India, arecanut is extensively used by all sections of society.

Chemical composition of green and ripe arecanuts

Values are expressed as percentage on dry-weight basis except moisture 

Climate

Arecanut is extensively cultivated in the tropical region. It is mostly confined to 28° North and South of the equator. It grows within a temperature range of 14°-36° C and temperature below 10° C and beyond 40° C adversely affects the crop. Due to susceptibility to low temperature, the palms do not perform well at altitude of 1,000 m above mean sea-level. It requires ample supply of soil moisture and plentiful of rainfall throughout the year (1,500-5,000 mm). It is sensitive to drought and in areas with low rainfall (< 750 mm/year), irrigation is necessary.

Soil

It can be grown in a variety of soils such as laterites, red loams and alluvial. The depth of soil may not be less than 1 m. The soil should be well drained without high water table. It can come up in soils acidic to neutral pH.

Propagation

Being a perennial, seed-propagated crop, much care is to be bestowed on the production and selection of planting materials. The different stages in the production of quality planting materials include selection of mother palm, seed nuts and seedlings and adoption of proper nursery techniques.

Selection of mother palms: Select mother palms showing earliness in bearing and high percentage of fruit set. It is preferable to select palms with shorter internodes, more number of leaves on the crown and producing at least 4 bunches in a year.

Selection of seed nuts: Select fully tree-ripen nuts from the middle portion of the middle bunch on the tree. Heavier nuts give higher germination percentage and produce vigorous seedlings. The nuts which float vertically with the calyx end pointing upwards when allowed to float on water are preferred. The selected bunches are lowered by means of rope and shown without delay.

Nursery techniques: Sow selected seed nuts soon after harvesting in nursery beds prepared under shaded condition with the stalk end up and with a closer spacing of 5-6 cm. Cover the seed nuts with sand and irrigate daily. Germination starts in 45 days and continues up to 3 months. Good quality seeds give 90-98% germination. Transplant 90 days old sprout having 2-3 leaves into the secondary nursery. Prepare secondary nursery beds with 150 cm width and of convenient length. Apply Farmyard Manure (FYM) @ 5 tonnes/ha as basal dose. Transplant sprouts at a spacing of 30 cm X 30 cm. Provide shade by growing banana, ivy gourd or by raising artificial pandals. Plants banana in advance at a spacing of 2.7m X3.6 m as shade crop. Provide irrigation during hot and dry months. Periodical weeding and mulching are necessary.

Selection of seedlings: Select good seedlings for planting in the main field when they are 12-18 months old. Seedlings with maximum number of leaves and maximum height should be selected for planting. Alternatively, a selection index can be worked out by multiplying leaf number by 40 and subtracting the seedlings height and select seedlings with higher index values.

Plant characters like girth at collar one year after transplanting and number of nodes ¹ years transplanting are highly correlated with yield. Plants with less than 20 cm girth one year after transplanting and less than 4 nodes 2 years after transplanting should be discarded.

Field Planting: Select site with deep (not less than 2 m), well-drained soil, without high water table and provision for irrigation. Arecanut palm is very delicate and cannot withstand extremes of temperature and exposure to direct sun. Plant tall, quick-growing shaded trees on the southern and western sides of the plantation to provide protection from the sun –scorching. Soil depth and water table are important aspects to be considered while selecting site, since it determines the development of root system.

Manure and Fertilizer

Apply green leaf or compost @ 12 kg/palm/year from the first year of planting onwards, during September-October. Apply NPK fertilizers for adult palm @ 100:40:140 g/palm/year for local cultivars, whereas for Mangala and other high-yielding ones the NPK dose should be increased to 150:60:210 g/palm/year.

Apply one-third dose during first year, two-third during second year and full from third year onwards. Under irrigated conditions, fertilizers should be applied in 2 equal split doses during September-October and February. Under rain-fed conditions, the second is applied during March-April after receipt of summer rains Manures and fertilizers are applied in basins around the palm dug to a depth of 15-20 cm and 0.75-1.0 m radius from the base of the palm, and covered with soil. The second dose is applied around the base after weeding and forked in. In acid soils, lime is applied @ 0.5 kg/palm/year once in ¹ year and incorporated by forking during April-May.

Water Management

Arecanut palm is very sensitive to drought. The palm should be irrigated during hot and dry weather at 4-7n days’ intervals @ 175 litres/palm depending on the soil type. When there is shortage of water, follow drip irrigation. Application of organic mulch around the base of the palm helps to conserve soil moisture. Proper drainage should be ensured by constructing drainage channels, 25-30 cm deep, for every ¹ rows of palms. They are to be cleared at the beginning of monsoon every year.

Cultivation

Keep the garden free from weeds and break up surface crust by light forking or digging after cessation of monsoon during October-November. In slopes, prevent soil erosion by terracing. Sow seeds of green manure-cum-cover crops such as Mimosa invisa, Stylosanthes gracilis and Calapogonium muconoides in April – May. Cut and apply them to the palms in September-October.

Intercropping: Arecanut as a sole crop does not utilize fully the natural resources and practically wasting 70% of the land area and 40% of the solar radiation and is ideal for intercropping. Local preference for choice of intercrops was observed-yam and tapioca in Kerala, citrus in Assam, betel vine West Bengal, cardamom in malnad of Karnataka and a general preference for banana in all tract. For mixed cropping, cocoa, black pepper, cinnamon, coffee, clove citrus and coconut are suitable. Cocoa is an ideal crop for mixed cropping with arecanut and this can be planted in pits dug 2.7m apart in between alternate rows of arecanut, in the centre. In all cases, intercrops should be manured adequately and separately.

Disease and Pest Management

Areca palm is prone to a number of diseases during its different stages of development. Forty fungal species, a bacterium and an algae parasite are associated with areca palm. Yellow leaf disease, a dreaded disease suspected to be caused by phytoplasm, also causes losses to its crop.

Koleroga/mahali/fruit rot: Koleroga caused by Phytophthora araceae is one of the major disease of arecanut. This occurs as an epidemic in the heavy rainfall areas of Karnataka and Kerala. The disease first makes its appearance after monsoon period. The first symptom is the appearance of water-soaked lesions on the nut surface near the calyx. The patches enlarge and nuts darken and they shed in large number. The fallen nuts soon develop whitish mycelial mass all over. Nuts of all ages are attacked and if unchecked, invade crown causing the leaves and bunches to whither. Sometimes, the infected nuts may not be shed and remain mummified in the bunches. Such type of infection is known as ‘dry mahali’.

This can be checked by spraying Bordeaux mixture (1%) twice a year, one just before the onset of South-West monsoon and another 40 days later. If monsoon is prolonged, give a third spray. Use Rosin soda adhesive to ensure tenacity of the spray deposit on treated subtrate. Remove and burn all fallen nuts since they act as a source of inoculum.

Anabe or foot rot: This disease is caused by fungus, Ganoderma lucidum. It is more prevalent in neglected gardens, causing 7% losses. Symptoms of the disease are akin to that of the draught. The initial visible symptom is yellowing of outer whorl of leaves which gradually extends to inner whorls followed by wilting and drooping. The development of inflorescence and nuts are arrested. Nuts already formed are shed. At later stages, the weakened crown topples off leaving a bare trunk. All around the base of the palm, brownish patches appear which exude a brown liquid. The interior of the stem at the basal region is discoloured and rotten, emitting a foul smell. The infection extends to roots and gets discoloured, brittle and dry. The fungal invasion interrupts uptake of water and nutrients by the palm, leading to yellow and wilting.

Since the infected stumps and roots act as the main foci of infection, strict phyto-sanitary measures are to be adopted by removing and destroying the stumps along with roots. Isolate affected palms by digging trenches 60 cm deep and 30 cm wide around, away from the base and drench with Captan (0.3%). Drench the soil with Bordeaux mixture (1 %). Before planting. Discourage growing of collateral hosts of the fungus like Delonix regia and Pomgamia glabra.

Bud rot: Bud rot is a fatal disease of areca palms caused by Phytophthora palmivora and characterized by rotting of terminal bud and surrounding tissues and ultimately killing the palm. In early stages of infection, scoop out affected rotten tissues by making longitudinal side splits. Apply Bordeaux paste and drench the crown with Bordeaux mixture (1 %).

Inflorescence die-back: Button shedding followed by die-back of inflorescence is a severe problem in arecanut plantations. This is primarily caused by Colletotrichum gloeosporiodes.Removal and burning of inflorescence help reduce the load of inoculum in the field. Spray Zineb (4 g/litre) twice, one just after female flowers are set and again 15-28 days later. Aureofungin 50 P at 50 ppm concentration is also effective in controlling the disease.                                                                                           

Bacterial leaf stripe: The disease is caused by Xanthomonas campestris pv. arecae. The symptoms are purely parenchymatous in nature causing water-soaked linear lesions parallel to the midrib of the leaflets. The lesions are covered with abundant creamy-white bacterial exudates on the under surface which is a striking feature of the disease. The entire leaflet in a frond may be affected resulting in complete or partial blighting. In severe cases, entire crown may be affected. When growing buds are affected, death of palm takes place. The disease is aggressive during monsoon. Younger palms (3-5 years old) are highly susceptible. Spraying or stem injection with tetracycline group of antibiotics at 500 ppm concentration is effective.

Stem bleeding: Caused by Thielaviopsis paradoxa, it is prevalent in isolated pockets in all arecanut-growing States of South India. Younger and middle-aged palms are more susceptible. Symptoms appear mostly on lower portions of the stem as small discoloured depressions which later coalesce and cracks develop with the progress of the disease, the fibrous layer disintegrates which hallows up to varying depths and brown gummy exudates oozes out. Crowns of affected palms get reduced in size followed by reduction in yield. The disease is serious in gardens with poor drainage. Improving the drainage may help in minimizing its incidence. Scooping out the affected portions and application of coaltar or Bordeaux paste is effective to reduce the incidence.

Yellow leaf disease: The disease is rampant in Kerala and Karnataka. Yellowing of leaves begin in the inner whorl, gradually spreading to the outer parts of the crown Chlorosis is finally observed on almost all leaves in the whorl from the edges of the individual leaflets to the midrib region. Withering of the tips starts and gradually spreads to the older portions of the leaf. The freshly formed leaves grow shorter and their laminac show unequal growth and flaccidity. In a few cases, wilting and shedding of leaves are also observed. The nuts are reduced in size, shriveled with their kernels often turning black and there is severe reduction in yield. Stem of the affected palms becomes spongy and friable, the conducting strands getting destroyed. In advanced stages, the stem breaks off at the top. Rotting of the roots is also observed. Association of mycoplasma-like organisms (Phytoplasma) with the disease has been confirmed. Water logging is a predisposing factor in the incidence of the disease. Lack of balance nutrition and unscientific cultivation practices make the palm susceptible to the disease. Since the disease is not amenable to management by conventional plant protection measures, other means of containing the disease should be looked into. They are:

• Physical condition of the soil should be improved by deep digging and adding sand/organic matter. In heavy sticky soils, gypsum @ 500 kg / ha may not be incorporated, once in two years prior to normal fertilizer application.

• Adequate drainage should be provided, especially during monsoon season.

• Phyto-sanitary and plan-protection measures should be adopted to control Anabe, bud rot, spindle bud and mite infestation.

• Sun-scorching of the stem should be avoided by covering with arecanut leaves or painting with lime slurry.

• Application of NPK fertilizers as per schedule along with lime and zinc @ 8.5 g each per palm.

Nut-splitting: Nut-splitting is more a physiological disorder than a pathological problem of universal occurrence. It is seen in well-grown, young and healthy palms. The growth of the pericarp does not keep pace with the development of kernel inside, causing splitting up of the pericarp. The split nuts drop and infection of the exposed kernel, renders them useless.

The splitting is due to excess flow of cell sap into the inflorescence in the very healthy palms. Hence, checking of excess flow either by making some deep wound at the base of the spadix or jamming the cells at the base when the nuts are half grown prevents splitting. Sudden flush of water after a period of drought also results in nut splitting. Potassium deficiency is also a probable cause of this malady. Application of potassium borax (2 g/litre of water) during early stages of the disease reduces splitting.

Sun-scorching or stem-breaking: Stem-breaking is another disorder, resulting from prolonged exposure of palms to severe solar radiation. The palms exposed to south west sun are more prone to stem-breaking. Symptoms appear as golden-yellow splits on the exposed side of the stem which turn dark brown and subsequently form longitudinal fissures. Further colonization by saprophytic fungi weakens the stem and finally break. Raising of fast growing trees in the south-west side of the garden protecting stem with dry areca leaves, trailing pepper vines on the stem, and adopting a suitable alignment for planting are recommended measures to minimize the disease.

Pests

The arecanut palm is attacked by over 90 insects and non insect pests which damage the foliage, roots stems inflorescence and nuts. Except spindle bug, mites, root grub, inflorescence caterpillar and pentatamid bug, the damage caused by other pests is not substantial.              

Spindle bug (Carvalhoia arecae): This is a serious pest multiplying rapidly with close of monsoon. The red and black adults and greenish nymphs colonize the top-most leaf axil at the base of the spindle. The bug sucks sap from the tender spindles resulting in reduction in size of the spindle. The infested portions on the lamina develop necrotic patches which later form shot holes. Severe leaf damage causes stunting of palms. Filling the inner-most leaf axils around the spindle with Phorate 10 % granules (10 g/ palm) at 3 months intervals is effective. Conveniently this can be placed in sachets of ¹ g (¹ per tree).

Mites (Raoiella indica, Oligonychus indicus): Mites are commonly found in arecanut gardens but only occasionally under prolonged dry weather conditions, it poses serious problems. The mites are of ¹ types-red and white. They attack both seedlings and adult palms. They infest the lower surface of leaf and suck sap and leaves turn yellowish-brown and dry up. The tender fruits are also attacked, causing malformation and shedding. Removal of heavily infested and dried leaves and burning help in eradicating the source of infection. Spraying under surfaces of leaves and crown with Dicofol (2 ml/litre) or Rogor (1.5 ml/litre) is effective.

Root grub (Leucopholis lepidophora): The grubs attack and feed on roots of both young and old palms. Due to root feeding, the leaves turn pale-yellow and yield is reduced. Keeping the garden clean, well-drained and free of weeds reduces its attack. Loosen the soil around the base of the palm to a depth of 10-15 cm and drench with chlorpyriphos (0.04%) suspension twice, in May and September. Repeat the application for 2 or 3 years for complete eradication of the pest. Soil application of Phorate 10 g around the palms is also effective.

Pentatomid bug (Hapylomorpha marmoreal): The adult and the young bugs suck sap from the endosperm of tender nuts, causing premature shedding. The dropped nuts have one or more pin prick-like marks on the surface. The adults are bronze coloured with brown spots and in young stages they are black with white spot on the leg. When tender nuts are not available, the insect migrates to other hosts like cowpea and bitter ground. Therefore these crops should be closely watched and the bug when noticed should be mechanically removed and destroyed. One round of spray with Endosulfan (0.05%) on the bunches is effective.

Nematodes: Burrowing nematodes (Radopholus similis) is the only endoparasite encountered in more than 50% of the areca root samples collected out of the 28 genera of plants parasitic nematodes reported in arecanut. Infested palms show general yellowing, reducing growth, vigour and yield. Appearance of orange-coloured lesions, blackening of tips of lateral and tertiary roots and rotting of roots are conspicuous symptoms. Integrated methods to control nematode disease are: use of resistant/tolerant varieties like Sumangala and Sree Mangala; avoid susceptible hosts like pepper and banana use nematode-free planting material; apply 5-10 kg of green leaves/palm, preferably of Glricidia or Crotolaria; apply neem cake (1 kg/palm/year); and apply Phorate (3 g/plant).

Biological control: Many coleopteran predators, chiefly coccinellids of arecanut mites, ar used. They are Aspects indicus, Cyleophalus semipictus, Stethrus keralicus and Stethorus parcepunctatus.

Physiological Disorders

Band or Hidimundige: Band is a physiological disorder of the palm due to adverse environment of the particular spot where the palm is standing. The first visible symptoms are the reduction in leaf size which turns brittle and crinkled with wavy margins. As the disease advances, there is reduction in inter-nodal length, formation of small bunches and tapering of stem. The crown shows a rosette shape due to failure of natural opening of leaves. The bunches become small and malformed. Roots are poorly developed, crinkled and brittle. Poor drainage, low soil fertility or environmental factors are possible causes of this malady. It has been reported from Maharashtra and Karnataka. Since biotic agents are not involved in its occurrence, spraying of plant-protection chemicals is of no value. Good soil management, Improvement of drainage and incorporation of copper sulphate and lime to soil could check it effectively.

Harvesting

Arecanut starts flowering from 3-4 years after planting. December-March is the main flowering season and harvesting period from June to July to get tender nuts and November-March for ripe nuts. The nuts are harvested at 45-50 days’ interval in 3 pickings. The nuts are processed both at tender as well as ripe stages. Harvesting is done either by climbing the palm or by using a long bamboo with a sharp sickle or hook attached to the end.