6.4 Motorised mistblowers

Cocoa was one of the first of the tropical tree crops to use motorised knapsack mistblowers for pest control using a fan to project the spray high into the cocoa trees. It is not uncommon to find trees in excess of 14 metres, but tree height management is strongly recommended for effective IPM. 

Mistblowers are designed to produce a fine spray or 'mist' and apply lower volumes than conventional knapsack sprayers (e.g. 20-100 L/ha rather than 200-1000 L/ha), many machines can also be adapted to apply granules and dusts, but these are not suitable for cocoa.

Mistblowers are the preferred method of insecticide application for area-wide control of mirids (capsids) and used by CODAPEC [1] for operational spraying in the most heavily infested parts of Ghana. 

They are also in widespread use by larger (>4 ha) farms and plantations: where the high initial capital cost of the machinery is offset by a higher work rate, and therefore reduced labour costs [2]. 

Since their early development in the 1950s, dozens of manufacturers have marketed a wide range of machines: each with different characteristics and a choice of settings for flow rate (output), etc.