12
Use of Communication Media in Changing
Rice Farmers’ Pest Management in the
Mekong Delta, Vietnam
K. L. Heong, M. M. Escalada, N. H. Huan and V. Mai
Introduction
Pesticides have dominated pest management practices of rice farmers for the past
30 years. The agrochemical era of the 1960s and 1970s that had strongly influ-
enced chemical oriented agricultural research and extension in the United States
(Rossiter, 1975) is still having a dominant effect in many developing countries.
Most Asian rice farmers have adopted pesticides as their main pest control tactic
(Heong and Escalada, 1997b) using insecticides more frequently than herbicides
and fungicides in most countries. In many cases, these insecticide applications are
unnecessary and are unlikely to result in an economic return. In the Philippines,
for example, about 80 per cent of insecticide sprays were misused because they
were applied at the wrong time and on the wrong targets (Heong et al, 1995a).
Farmers targeted most insecticides at leaf-feeding insects in the early growth stages
(Heong et al, 1994; Mai et al, 1997). The most common species is the rice leaf
folder (Cnaphalocrocis medinalis Guenee), which causes highly visible damage
symptoms. Farmers generally perceive that the damage due to these pests (often
referred to as ‘worms’) reduces yield so they apply insecticides (often referred to as
‘medicine’). The less expensive and highly toxic chemicals, such as methyl par-
athion, monocrotophos and methamidophos, are frequently used.
However, research has shown that the common leaf-feeding insects, such the
leaf folder, whorl maggot (Hydriella philippinensis) and army worms (like Spodop-
tera litura) that often attack the rice crop during the vegetative stages arc rarely in
sufficiently high densities to reduce yield. Even when all hills were damaged by
whorl maggots, no yield loss could be detected (Viajante and Heinrichs, 1986;
Reprinted from Crop Protection 17(5), Heong K L, Escalada M M, Huan N H and Mai V, Use of com-
munication media in changing rice farmers’ pest management in the Mekong Delta, Vietnam, 413–
425, Copyright (1999), with permission from Elsevier.