Red Palm Weevil Control for Date Palm Trees

Damage

Almost the entire damage is caused by the larvae that feed on the inner tissues of host palm near the crown or some part of the trunk region.  In coconut the damage is towards the upper portion of trunk but in date palm the damage is more at the base of the trunk.  The external symptoms produced by the pest attack include the presence of small bore holes on the stem, oozing out of brown viscous liquid, spit out chewed tissue fibers and longitudinal splitting of leaf bases.  Sometimes the trunk becomes hollow with severe damage to the inner tissues.  In the final stages the crown gets toppled as a result of severance of crown from main stem.

Rating damage intensity

Coconut palm damage percentage: Generally the extension agencies record the number of infestions by the pest to understan its severity in a given location, region, province etc.  This will help in formulation extension programs to suit the local needs.

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Detecton of pest damage

The infestation may be categorized into three damage stages such as,  mild, medium and severe.  The palm with mild damage will have small holes and oozing of brown viscous liquid.   In the second stage, the palm will show clear indication of damage, with extrusion of chewed up fibers and bad smell emanating from the wounded tissues.  The frass mixed with sap forms small lumps and drops to the ground in some young palms.  The severely damaged palm may show yellowing of leaf on the side of damage, besides all the above symptoms in a much more exagerated fashion.  The damge to stem might be severe and can only be estimated upon proper inspection and cleaning of wounds. The palms in the first two categories of damage can be rescued to a large extent but the revival of the severely affected palms depends on several factors.

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Monitoring of pest

Coconut palm monitoring: The palms in the age group of 5-20 years should be regularly surveyed for identifying any infestation. This has to be done atleast once in a month.

Date palm monitoring: In date palm gardens, young palms should be checked thoroughly.  Palms with offshoots on the stem should be subjected to more vigorous inspection so as to identify any hidden pest infestation.  As the offshoots breakout from the side of the mother’s stem, many crevices are created, facilitating the entry of weevil adults for egg laying and further development.  Hence, the growers should employ good methods of survey and surveillance to avoid any fresh infestation.

Management of Red Palm Weevil

1. Preventive methods: The prophylactic or preventive methods are meant to delay or prevent the entry of the palm weevil into new gardens, locations, or regions.  For this purpose most vulnerable stages of the palms are treated with pesticides, cultural practices like leaf cutting are modified, phytosanitation, plant quarantine besides use of pheromone trapping system to attract and kill the adult weevils.

2. Curative methods: After detection of infestion, most suitable method of control should be applied. Detailed discussion is given elsewhere.

Curative methods

Once the damage is identified based on symptoms, it is important to take up plant protection measures at the earliest.  Usually the damaged tissue is removed and a suitable pesticide is applied to the damaged part.  The part of damaged stem is drilled with a few holes and an effective chemical in appropriate dose is poured into the holes and sealed.  The systemic pesticide will penetrate the stem tissues and kills the pest stages present.  Even fumigation is resorted in some cases depending on the type of damage.

If any palm is killed, it is better to cut it into pieces, apply pesticide and finally burn.  The material should be properly burnt to prevent escapes.  Until the dead palm is disposed of, the adult weevils continue to emerge from inside and spread in the entire garden and cause great damage.

Pheromone Trapping

Attract and Kill

Taking advantage of the adult weevils attraction to the fermenting liquids especially sap from the palm, a poisonous broth was used to bait and kill the weevils the past.  This techniques was continuously refined and sugarcane baited traps were successfully used for collection of weevils for a long time.

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Biocontrol agents

In nature there are some predators like earwigs which feed on the loose eggs.  However, there are no biocontrol agents capable of reducing the pest population.  Several laboratories have tested and tried to introduce biocontrol agents like entomopathogenic nematodes, fungal pathogens etc., but with very little success.  Although some success rate was reported in some regions, it was mainly confined to cooler weather conditions only.  Hence, more and more innovative ideas should be attempted.

Biotechnology

Many advances have been made in the frontier areas of biotechnology, tissue culture, genetic evaluation, genomics of plants and insects.  Some mind boggling technologies which were only hypothetical have been transformed into reality in the form of GM crops.  Along with positives, there are several issues concerned with the introduction of GM crops tolerant to insects, especially in the case of food crops.  We are definitely going to see many innovations and breakthroughs in the field of agricultural sciences.  As long as these cutting edge technologies are within the stipulated parameters, one need not be unnecessarily worried.  Unless we think differently certain problems continues to elude us.  Therefore, we should strive hard to keep the new areas of research highly innovative but at the same time should not create any new problems. 

Tail piece

Before I conclude, the management of red palm weevil is possible only with the cooperation of growers, farmers, governemental departments, dedicated researchers, policy makers and research organizations.  Today the world we live in is like a global village.  If somewhere some new pest or emerging pest appears for the first time, it is imperative for us to pass on the information as quickly as possible to every one who grows that plant.  This helps the world community to be better prepared and equipped with adequate resouces to solve the problem.  This effort, I hope will go a long way in meeting the ever increasing needs of the agricultural community to produce quality foods with out sacrifing the yeilds.  Stakeholder in the managemnt of Red Palm Weevil are encouraged to express their views and bring breakthrough news for the benefit of the entire research, extension, and farming fraternity.