January 2010. Mites on coconuts in India. A popular article from a website (Expressbuzz.com) on elicited comments from members.

The article stated the following:

Mites (Aceria guerreronis) have wreaked havoc on coconut plantation in coastal Kendrapara and Jagatsinghpur districts hitting the livelihood of thousands of farmers hard.

With participation of farmers, the horticulturists of both the districts are now experimenting with a group action to control the menace in a contiguous area. ???We are providing medicines to the coconut growers to treat the affected coconut trees,” said an official of horticulture office of Jagatsinghpur.

Shortage of climbers has been a handicap in fighting the menace, according to some coconut farmers. The mite spreads, primarily, through wind.

After being first noticed in 1997 in Elanchi panchayat in Ernakulam district of Kerala, the menace spread to other states over the years. Three types of control measures – use of a neem-based miticide called azadiractin, crown spraying, root feeding and stem remedies are being used to fight the menace.

The results and impact of the measures will be documented, an official said.

The awareness programmes also envisage joint meetings of farmers and farmer leaders, including panchayat president and ward members, and agricultural officials. Amid mounting pressure from coconut farmers, the Agricultural Department and horticulturists recently provided pesticides and medicines to a large number of farmers.

In response, a member wrote the following:

The Eriophid Mite (Aceria guerreronis (Keifer) (Acarina: Eriophyidae) which was a minor pest of coconut in India has become a major pest recently.

The attack of this mite was first recorded in 1965 in Guerrero, Mexico. Later it was reported from Ivory Coast, Brazil, Costa Rica and other places. The first Indian report of this pest is from Ernakulam District of Kerala during 1998. The sporadic occurrence of this pest is reported from almost all the 14 districts of Kerala, Tamil Nadu, Karnataka, Andhra Pradesh and Kalpeni Island of Lakshadweep. As per the recent survey conducted in Kerala (13-18 December 1999) about 589 lakh bearing palms are affected. This accounts for about 42% of the total yielding palm population. The estimated crop loss is about 22%. A roving team to study the intensity of infestation has identified its occurrence from all the South Indian States and Union Territory of Lakshadweep.

The mites are minute and are not visible with the naked eye; they are 200-250 microns long and 20-30 microns wide. The life cycle is complete in 10-12 days. The mites live under the perianth (cap) and cause injury by feeding on the soft tissues. Though the mites are microscopic their damage is enormous and hundreds of mites are present on each button and tender nut. The nuts show brown discoloration in patches on the husk. In case of severe attack, the buttons are shed. In other cases, the nuts are deformed and undersize with poor development of kernel and husk.

The mites are spread by wind, and multiply quickly. The mite was noticed only in a limited area in 1998, now it is a major pest of coconut in India.

Control measures

By adopting the following integrated plant protection measurers, the mite population can be reduced considerably:

1. Adoption of phytosanitary measures in coconut gardens such as cleaning the crown of the palm, keeping the plantation clean and burning of all immature nuts fallen due to mite infestation.

2. Spraying biopesticides on the bunches:
a) 2% neem oil – garlic emulsion (20ml neem oil + 20g garlic + 5g bar soap in 1 litre water). Emulsion has to be prepared on the same day of application.
b) Other neem-based pesticides at 0.004% (Azadirachtin). If the pesticide formulation contains 1% Azadirachtin, 4ml is used in 1 litre water.
Wherever spraying is difficult root feeding may be resorted to with Azadirachtin 5% formulation (7.5ml+7.5ml water) or Azadirachtin 1% formulation (10ml + 10ml water).

3. Spraying has to be done 3 times a year ??? December-February, April-June and September-October. While spraying, ensure that the spray falls over the perianth region especially on buttons and tender nuts. On average, 1-1.5 litre spray is required per palm. Care should be taken to harvest mature bunches before spraying.

4. The following health care practices also may be adopted.

?? Recycling of biomass generated within the coconut system by vermi compost or by using lignin-degrading fungus.

?? Growing green manure crops (like sunhemp, cowpea, Calapagonium, etc.) around the palms (2 m radius) and incorporating them into the soil; these act as mulch during summer, slowly decomposing and providing nutrients.

?? Application of recommended fertilizers, in two split doses, as per the package of practices prevailing in the respective states.

?? Recommended level of irrigation during summer months, i.e., 250-500 litres of water per tree per week (based on evapotranspiration in the given area).

?? Soil moisture conservation by following methods.

o Burial of coconut husks.

o Mulching around palms (2m radius) with coconut leaves/green manure / green leaf manure.

o Mulching with coir pith wherever available (2m radius).

Biological control may be a good alternative. A paper in press in the journal Biocontrol (see below) showed the predatory mite, Neoseiulus baraki, has good promise. It should be noted that this predatory mite species is extremely cheap to produce and is commercially available in many countries. These predators can get under the perianth (cap) where the coconut mites escape sprays of chemicals.