Pest Management in Coconut
- More than 547 pests have been reported on coconut palm world wide, at various stages of crop growth.
- Among the 65 pests recorded in India, the Coconut rhinoceros beetle, the Asian red palm weevil, the Coconut leaf eating caterpillar, the Cockchafer beetle are the major pests occurring in most of the coconut growing tracts.
- The other minor pests include mites, scale insects, mealy bugs, coried bug, defoliating caterpillars and termites which occasionally assume in damaging proportions. Rodents like rats, andicoots etc., also affect the coconut palm.
Coconut cockchafer beetle: Leucopholis coneophora Burm
- Leucopholis and other related species of cockchafers attack roots of coconut and other intercrops adversely affecting the vigor of the palm and yield. The grub occurs in sandy and sandy loam soils feeding on the root of coconut resulting in yellowing of the leaves and loss of yield.
- The beetles lay eggs in soil and immature grubs feed on the grass roots and soil organic matter. The second and third instar grubs are voracious feeders and feed on growing tender roots. Larval stage lasts for a longer period. The insect pupates inside the soil and emerges from the soil on receipt of monsoon showers.
Integrated pest management schedule for white grub includes
- Ploughing during pre and post-monsoon period to expose the pest for predation and also to collect and destroy the grubs.
- Collection and destruction of adult beetles during emergence (i.e., May/June and September/October) on receipt of monsoon showers.
- Installation of light traps to monitor and catch the beetles.
- Application of phorate 10 G (Thimet 10G) @ 100g/Palm twice during pre and post-monsoon season.
The coconut leaf eating caterpillar; Opisina arenosella W1k.
Infected Leaf Lets
- It is distributed in the coastal and backwater area. The pest out break occurs during summer months. The caterpillar lives in galleries made of silken threads and their fecal matter on the lower surface of the leaflets.
- The life cycle is completed in two months. Continuous feeding on the green tissues results in the reduction in photosynthetic area and the leaves dry up giving a burnt up appearance. Infestation results in reduced yield.
Integrated management of this pest includes
- Cutting and burning the heavily affected outermost 2-3 leaves.
- Release of larval parasitoids such as Goniozus nephantidis Mues., Bracon hebetor Say and pre-pupal parasitoids like Elasmus nosatoi Habu at fixed norms.
- The dose is to be fixed based on the target stages of the pest present at the time of observation. The norms fixed for the release are @ 20.5%, 49.4% and 31.9% respectively for larval, prepupal and pupal stages.
- If all the three stages of the pest is noticed 40% larval, pre-pupal and pupal parasitoids are to be released to have a good biological suppression of the pest.
- Spraying with dichlorvos 0.02% (1 ml in 2 litre water)/Malathion 0.05% (1 ml/litre water)/endosulfan 0.05% (1.5 ml/liter water)phosalone (zolone) (1.5 ml/liter water).
- Root feeding of monocrotophos: select a fresh and live root, cur sharply an angle to get maximum surface area and insert the root in the monocrotophos solution (monocrotophos 36 EC 10ml +10 ml water) in a polythene bag. This is recommended for coastal areas.
- Stem injection of 10 ml monocrotophos 36 EC for maidan areas (method as described under red palm weevil). As indicated earlier, before root feeding and stem injection of pesticide, harvest the nuts and a waiting period of 45 day must be observed for harvest.
The Asian Palm weevil; Rhynchophorus ferrugineus
- Adults are attracted to wounded palms. Weevils lay eggs on spindle and tender leaf through injuries caused by rhinoceros beetle as well as through the natural splitting in the leaf base.
- The larvae tunnel into the tree trunk and feeds on the inner tissues. When the larva reaches the terminal bud of the crown region, it results in the death of the palm. In general palms of 5-20 years are susceptible. Life cycle is completed with in three months. Pupation takes place inside the trunk.
- The external symptoms include the presence of small holes on the stem, oozing out of brown viscous fluid, extrusion of chewed up fibers, longitudinal splitting of leaf bases and yellowing and wilting of leaves of the inner and middle whorl. In severe case, the crown of the palm topples.
- Aggregation pheromones have been identified for this weevil as 4-methyl-5 nonanone.
- The integrated pest management measure for the pest is as follows:
Sanitation & Cultural Method
- Crown cleaning
- Removal and destruction of dead palms to avoid the attraction of weevils from neighboring areas.
- Avoid injury to palm.
- Injuries to be treated with coal tar + carbaryl (sevin)
- When green leaves are to be cut, it can be done leaving a petiole length of 120 cm.
- Palms affected with bud rot/leaf rot and rhinoceros beetle are to be treated properly.
- Prophylactic leaf axil filling with a mixture of sevidol 4:4G 25g and sand 200g.
- As a curative, inject 0.1% Endosulfan (2.8 ml/litre water)/ 0.1% dichlorvos(2.8ml/l water) or 1.0% sevin 50 WP (20 g/litre water) into the trunk. Drill a downward slanting hole and inject into the stem at about 1.5 m above ground level and plug with clay. (Before treating the palm, harvest the nuts and a waiting period of 45 days must be observed for harvest of nuts.
- For trapping adult weevils, place the insecticide treated split coconut petiole (approx 250g) in a mud pot having fermented toddy (500 ml).
- Placement of pheromone sachets (as described earlier under rhinoceros beetle).
The coconut rhinoceros beetle; Oryctes rhinoceros (L)
- Adult rhinoceros beetles burrow into the growing point of palms and feed on unopened fronds, causing damage of inflorescence and reduction in photosynthetic area resulting in decreased or delayed fruit production.
- Prolonged attacks can kill mature palms by defoliation and young palms if the growing point is destroyed. The wounds produced by the beetle provide entry points for diseases and the palm weevils.
- It breeds in decaying organic matter, such as felled rotting palms and manure pits and usually becomes a major problem in newly planted or replanted plantations. Eggs are laid on the breeding sites, and the grubs feed on these materials for about six months. Then the pupation takes place in cocoon.
- Aggregation pheromones have been identified for the pest as ethyl 1-4 methylactanoate
- Integrated Pest Management includes,
- Crown cleaning- Once in a year crown has to be cleaned to avoid the colonisation of insects.
- IExtraction of adult beetles with beetle hook and filling bore holes with Mancozeb + sand mixture (3g + 1kg).
- ITreatment of breeding sites with 0.01% carbaryl 50 WP (dissolve sevin 50 WP 1 g in 5 litre water).
- After crown cleaning, treat the crown with carbaryl: r-HCH 8G (Sevidol 4:4G)+ sand mixture at 1:8 ratio. This can be applied during pre and post monsoon period at 45 days interval.
- Application of green muscardine fungus, Metarhizium anisopliae @ 5 x 1011spores/m3 in the breeding sites for biological suppression of all stages.
- IRelease of baculovirus infected rhinoceros beetle @ 10-15 beetles/ha.
- IPheromone traps: Pheromone trap @ 5 traps/ha can be placed.
- IThe dispenser may be hanged in a plastic bucket having 2 liter of insecticide solution (1.5ml Endosulfan 35EC + 2liter water) once in a week. Trapped beetles can be disposed off.
Slug caterpillar : Macroplectra nararia
- Affected palms will be devoid of green parts of the leaflets, only the midribs of the leaflets on the lower fronds are seen.
- Spraying Chlorpyriphos (0.05%) or Monocrotophos(0.05%). Since the insect pupates in the axils at the base of the fronds, pack this space with a 1:1 mixture of sand and carbaryl.
Recent Burning Problem in Karnataka
Eriophyid mite (Eriophyis guerreronis) on coconut and their management
Nature of damage and symptoms
- Large number of Eriophyid mite (Eriophyis guerreronis) colonize on the tender portion of nut (button) covered by the inner bracts of the perianth and suck the sap from meristematic tissues. As the feeding sites grow out the perianth, they appears as white or creamy triangular bands or patches.
- These patches turn into yellow and them become brown and develop fissures and finally appear as warts.
- Due to the drying tissues of coconut the enlargement of the nut is affected leading to drastic reduction in the size of coconut when the infestation is high in the early stages of development, the button shedding is also heavy. Because of the hampered growth of affected nuts the kernal size and quality are affected. It is estimated that the damage may result in about 25 per cent yield loss of copra content.
Mode of Spread
- This mite is spread/dispersed through wind in long distance and spread from one tree/palm to other or one garden ot another garden quickly. Mites also spread from transportation ofr affected mature or immature nuts from one place to another.
- Root feeding with monocrotophos 10 ml (7 ml/litre if coconut plam is <10 years old)
- Stem injection by using syringe -- Syringe technique is developed by scientists from University Agrl. Sciences, Bangalore.
- Spraying of Acaricide, Dicofal (40 ml/10 litres of water) OR Ethion (10 ml/10 litres of water) OR Triazophos (40 ml/10 litres of water) 6-7 months old bunches for complete wetting of spary solution on bunches.
Biological control: Two entomogenous fungi
- Hirsutella thompsoni , Hirsutella nodulosa } have been found to be effective in keeping the mites under check.
Special note to coconut farmers
- Fore effective control of mite damage all the farmers together take-up the compaign control/mangement programme.
- After root feeding and stem injection, take up spraying once or fifteen days after treatment.
- Spray four times in a year, i.e., once in 1 1/2 to 2 months (except rainy season). At the time of harvesting of immature or mature nuts, take-up spraying for reducing the spraying cost, for this purpose better to use hand operated sprayer.
- Root feeding and stem injection (Monocrotophos) only once in a year or maximum twice. Don't use the coconut nuts upto 45 days after treatment. If any mature nuts found on the tree, harvest the nuts before treatment.
- Donot transport the nuts or seedlings from mite infested coconut gardens, also test/scout the nuts frequently in the garden. If found any mite incidence on immature nuts take up control measures to preven the spread of mites to other trees.
Non insect pests
Eriophyid Mite on Coconuts
- The pest problem caused by Eriophyid mite, Aceria gurrerronis (Kelfer) on coconut has reached alarming proportions threatening the very survival of the coconut industry in South India.
- In India, the pest was first reported in later part of 1997 from Ernakulam district of Kerala. Within 2 years it has spread to most of the districts in the states of Kerala, TamilNadu and karnataka.
- In karnataka, serious life infestation occurred during 1998 and at present out of the 14 affected districts, Tumkur, Chikkamagalur, Chitradurga, Bangalore, Mandya and Mysore are most prove.
- The factors or the combination of factors responsible for its entry and spread in India are not yet clear. They could be:
- Low population of pest existing earlier which later multiplied into large number owing to a breakdown of an existing control mechanism or a sudden change in ecological factors.
- Inadvertent introduction of the pest into India from other countries.
- Excessive usage of chemical pesticides resulting in the elimination of parasites and predators of mites leading to the resurgence of the pest.
Symptoms of the attack
Large nuts damaged by Mites
- Feeding of adults and nymphs in the meristematic region under the perianth causes physical damage.
- The earliest symptom of attack on the buttons is a triangular patch, yellow in colour, emerging from underneath the perianth. Later the surface becomes necrotic and suberised. Uneven growth results in distortion and stunting of the coconut leading to reduction in coconut yield
- Losses are compounded by the losses in husk quality and additional labour required for dehusking.
- It seems that mites can kill seedlings by feeding on their meristamatic tissues at growing point, however, so far, damage to coconut seedlings by the pest has not been reported in India.
Some of the eco-friendly control measures are
- Neem oil + garlic + soap emulsion (2%)
- Neem oil + garlic + soap emulsion (2%) + wettable sulphur (4%)
- Pongamia oil + garlic+soap emulsion (2%)
- Pongamia oil + garlic + soap emulsion (2%) + wettable sulphur (4%)
- A homeopathic preparation (20 ml) for stem injection
- A herbal preparation (sanjeewak-20 ml of 50%) for stem injection.
- Use of a bio control agent. T stanes and company limited., Coimbatore, developed a technology for mass production of a biocontrol agent of this mite-a fungus known as Hirsutella thompsonii developed as a water dispersible wettable powder formulation containing 1 x 107 spores/g, commercially named as BIO-CATCH.
- Another powder- a product "Solu Neem" powder (product to be registered) for stem injection for the management of coconut mites developed by Vittal Mallya Scientific Research Foundation, Bangalore.
- Select pencil thick healthy root 2-3 feet away from the trunk, give a slant cut and tie a polythene cover containing 10ml Monocrotophos in 10ml water such that the cut end is immersed in the solution. In irrigated gardens, stop irrigation for 15-20 days and then feed the roots with monocroptophos-15-20 days later spray young nuts with 0.4% Dicofol @1.5 l/palm.
Note: Harvest nature nuts 40-45 days after feeding the roots with Monocrotophos.
Rats: (Rattus rattus)
- It is a common species and a serious pest in many coconut growing countries causing a damage up to 5 to 10%, sometimes even 50% also. In India the burrowing rat (Bandicoot bengalensis) is also a serious pest.
- This burrows the soil near the base of the seedling along with nuts, scoop out the nuts and feed the entire internal contents making the seedlings dry. The house rat (Mus bodooga) enter the crown of the palm and burrow into the immature nuts and drink the water and eat the soft meat. Such attacked nuts are damaged and shed. The rat damage can be seen at the stalk end.
- Control measures include use of traditional traps, poison baits and banding the metal sheets found the trunk. Use of third generation rodenticide i.e., Bromadiolone 0.005% @50g per feeding site will also be very effective and safe method of rodent control.
- They cause physical damage to inflorescence and nuts. Seedlings in the nursery are also attacked. Proper watch and ward is the only means to avoid damage by monkeys.
Western ghat squirrels
- They damage coconut inflorescences
- Introduction of VAM, Pasteuria penetrans and Paecilomyces lilacinus in the nursery and at transplanting.
- Neem oil cake at 1.5kg/plant, pongamia cake 1.5kg/plant and Glyricidia leaves at 5kg/plant applied twice a year during May-June and October-November.