February 2013. An outbreak of a scale insect on coconuts has occurred at a resort in the Maldives; about 6000 palms are affected. The underside of the lowest leaves are covered with the pest. It’s all whitish in appearance. The resort staff were asked to cut out the lower leaves and to burn them to reduce the huge population of the pest. Also, since it is a new pest and we have not come across it earlier, it is very important for us to take measures to prevent its spread to other islands, and the resort staff have been asked not to take palms elsewhere. For some islanders coconut palms make revenue while in resorts they are an important plant for the natural beauty. The resort says that it has not brought in plants from outside.
The type of scale was not discussed; instead various approaches to control.
A member suggested an integrated pest management approach using a chemical insecticide such as lambda-cyhalothrin or because it is a resort an “organic” treatment: liquify 2 medium onions, 2 garlic cloves and 10-15 hot chili (250 g) and put to boil in a gallon of water. When boiling, add the paste and continue boiling for 5 minutes (no more), retire from the fire and allow to cool. Filter and then add the “soup” 20 cc per liter water. Spray palms every 4 days for 1 month.
It was also suggested that the fronds are first sprayed with insecticide, with neem oil, and after 5 days the lower leaves cut; otherwise, the immature scales (the crawlers) could be taken by wind to other trees.
Only adult male armoured scale insects fly, so flight is not a problem here. However, the scales are dispersed as tiny first-instar crawlers on the wind. So cutting the infested foliage could help spread the infestation locally if the shaking of the fronds releases crawlers into the air.
A mineral oil emulsion (or even just a soap solution) spray would be best before cutting; it would kill crawlers without injuring any natural enemies already present. Any cut fronds should be treated very gently and burned on the spot.