Advisory work, by its very nature, is an intermediary between the re­ search worker and those who apply the results of his research. The challenge of advisory work is to devise means of and find pathways for transmitting research results to the user, overcome the reluctance of the latter to change, and often combine novel ideas with well-estab­ lished traditions. Nowhere is this challenge greater than in farming. This is especially true in developing countries, where the gap in the educational level between research workers and farmers may be ex­ tremely wide. Moreover, village-level advisers are often overburdened with non-professional functions and are not sufficiently backed up by well-trained professional advisers. Thus, in many of these countries there is a serious discrepancy between the knowledge available and that needed and actually applied on the farm. Advisory work in crop protection is no exception, but profits to some extent from two facts: (1) because of the potentially catastrophic nature of pest attack, governments often operate a supervisory crop protection service, the staff of which may be able to dispense some pest control advice; and (2) the staff of pesticide distributors tends to fill, at least in part, the need for advice on how to fight pests and dis­ eases with chemicals.