quantity of undiluted substance used. For the analysis, we quantified the amount of
each pesticide used in monetary terms (baht), in terms of active ingredients (kg) and
its potential environmental impact, for which we used the Environmental Impact
Quotient (EIQ) (Kovach et al. 1992; Levitan et al. 1995). The EIQ represents a
holistic approach quantifying the hazard potential of a pesticide, and differentiates
between the potential risk for consumers, farm workers and the environment.
Farmers mentioned over 50 different pest problems affecting their crops, and
Table 4.2 shows a list of the 16 most frequently mentioned of these. We should note
that this list is based on a self-assessment carried out by the farmers in relation to
the pests affecting their fields, those identified using pictures. As a result, these
assessments might differ from those made by experts. Farmers are, for instance,
usually well able to identify insect pests, but have more problems distinguishing
plant diseases from fungi or bacterial infections. Thrips and beet armyworm were
the most common pests identified, affecting 27 % and 17 % of the observed fields
respectively. Thrips affected 89 % of the observed greenhouses growing bell pepper
and 70 % of the observed fields growing roses.
The effect of these pest problems on crop yields, as estimated by the farm
managers, is shown in Fig. 4.2, revealing that high value crops were also subject
to high rates of actual yield loss. For instance, roughly 40 % of bell peppers and
roses in the Mae Sa watershed were lost because of pests in 2010.
As can be seen from Fig. 4.3, there was a positive association between the
profitability of a crop and the intensity of pesticide use. Few pesticides were applied
on the paddy rice fields – as the crop is almost solely used for home consumption, or
to the feed maize – as this is used to feed the farm animals. Relatively few pesticides
were also used on litchi, as the profitability of this crop was low and farmers were
trying to reduce costs (Schreinemachers et al. 2010). Chayote (Sechium edule) was
the only commercial crop on which relatively few pesticides were applied, as it is
not much affected by pests. The greatest amounts of pesticide use were reported for
bell peppers, tomatoes and cut flowers (chrysanthemums and roses).
Schreinemachers et al. (2011) showed that farmers in the study area were extremely
dependent on synthetic pesticides for managing pests, and we found that synthetic
pesticides were used by 97 % of farmers, with 77 % relying solely on synthetic
pesticides to control pests. Synthetic pesticides were applied across 79 % of the planted
area, while non-synthetic methods were used on only 8 %. Farmers in the Mae Sa
watershed used 13 kg of active ingredients per hectare, which is about 3.5 times the
national average in Thailand, and of this amount, 54 % was fungicides and 29 % was
insecticides while herbicides accounted for only 11 % of the amount of pesticides used.
4.3.2 Pesticide Use in the Paddy Rice Systems of Chieng Khoi,
Vietnam
To assess how rice farmers in mountainous areas in north-western Vietnam use
pesticides and how they perceive their own exposure to pesticide risk, we randomly
selected 50 rice farmers for interviews in 2010, 10 farmers from each of the five
154
M. Lamers et al.
each pesticide used in monetary terms (baht), in terms of active ingredients (kg) and
its potential environmental impact, for which we used the Environmental Impact
Quotient (EIQ) (Kovach et al. 1992; Levitan et al. 1995). The EIQ represents a
holistic approach quantifying the hazard potential of a pesticide, and differentiates
between the potential risk for consumers, farm workers and the environment.
Farmers mentioned over 50 different pest problems affecting their crops, and
Table 4.2 shows a list of the 16 most frequently mentioned of these. We should note
that this list is based on a self-assessment carried out by the farmers in relation to
the pests affecting their fields, those identified using pictures. As a result, these
assessments might differ from those made by experts. Farmers are, for instance,
usually well able to identify insect pests, but have more problems distinguishing
plant diseases from fungi or bacterial infections. Thrips and beet armyworm were
the most common pests identified, affecting 27 % and 17 % of the observed fields
respectively. Thrips affected 89 % of the observed greenhouses growing bell pepper
and 70 % of the observed fields growing roses.
The effect of these pest problems on crop yields, as estimated by the farm
managers, is shown in Fig. 4.2, revealing that high value crops were also subject
to high rates of actual yield loss. For instance, roughly 40 % of bell peppers and
roses in the Mae Sa watershed were lost because of pests in 2010.
As can be seen from Fig. 4.3, there was a positive association between the
profitability of a crop and the intensity of pesticide use. Few pesticides were applied
on the paddy rice fields – as the crop is almost solely used for home consumption, or
to the feed maize – as this is used to feed the farm animals. Relatively few pesticides
were also used on litchi, as the profitability of this crop was low and farmers were
trying to reduce costs (Schreinemachers et al. 2010). Chayote (Sechium edule) was
the only commercial crop on which relatively few pesticides were applied, as it is
not much affected by pests. The greatest amounts of pesticide use were reported for
bell peppers, tomatoes and cut flowers (chrysanthemums and roses).
Schreinemachers et al. (2011) showed that farmers in the study area were extremely
dependent on synthetic pesticides for managing pests, and we found that synthetic
pesticides were used by 97 % of farmers, with 77 % relying solely on synthetic
pesticides to control pests. Synthetic pesticides were applied across 79 % of the planted
area, while non-synthetic methods were used on only 8 %. Farmers in the Mae Sa
watershed used 13 kg of active ingredients per hectare, which is about 3.5 times the
national average in Thailand, and of this amount, 54 % was fungicides and 29 % was
insecticides while herbicides accounted for only 11 % of the amount of pesticides used.
4.3.2 Pesticide Use in the Paddy Rice Systems of Chieng Khoi,
Vietnam
To assess how rice farmers in mountainous areas in north-western Vietnam use
pesticides and how they perceive their own exposure to pesticide risk, we randomly
selected 50 rice farmers for interviews in 2010, 10 farmers from each of the five
154
M. Lamers et al.