Nonchemical pest control methods

Indicator definition and method of calculation

The indicator shows the area that has not been treated with chemical pesticides, and is calculated as the crop area that is not treated with chemical pesticides divided by the total cultivated agricultural area. The cultivated agricultural area includes the total arable and permanent crop land, assuming that pesticides are not used on temporary or permanent pasture. Non-chemical pest control methods include, for example, tillage (e.g. ploughdown of allelopathic residues, that is, plants whose roots and residues can suppress the growth of many other plants, including weeds), crop rotation, biological control (e.g. parasitic organisms for control of insect pests), pheromones and hand weeding.

Recent trends

Chemical pesticides are not used in organic farming; hence Fig. 8.4, showing trends in the share of agricultural land under organic farming, can also be considered to reflect trends in the area where only non-chemical pest control methods are used. Organic farming systems also include many other requirements and, consequently, the area where chemical pesticides are not used often exceeds the area under organic farming. Examples of such countries include Germany, Spain and the United Kingdom, where significantly more farmers are now using non-chemical pest control methods than in the 1980s.

Fig. 8.4 Share of the total agricultural area under organic farming: Early 1990s and mid-late 1990s (OECD, 2001).

Notes:

1. Data for the early 1990s are not available.

2. Percentage for the early 1990s equal 0.003%.

3. Data for the United States are taken from Welsh (1999).

Over a third of Canadian farms and field crop area do not apply commercial pesticides (Table 8.2). In addition to the use of non-chemical pest control methods, Canada has developed other indicators for pesticide management (timing of herbicide applications, timing of insecticide and fungicide applications and sprayer calibration) (McRae et al. 2000). The indicators suggest that herbicide application was triggered by the level of economic injury to the crop on about 20% of treated crop land. Also farmers were more likely to apply herbicides at a certain stage of crop growth or to use the first sign of pests to time pesticide applications. Moreover, nearly 70% of farmers calibrated sprayers only at the beginning of the crop season (McRae et al. 2000).

Table 8.2 Pest control methods used by farmers excluding the use of chemical pesticides, Canada, 1995 (McRae et al. 2000).

% of field crop

Pest Control Method Number of farms % of farm numbers1 area treated1

Tillage 53.805 26 28

Crop rotation 99.970 49 56

Biological control 4.570 2 2

Hand weeding 14.900 7 4

Other 2.605 1 1

No non-chemical 80.510 39 34 method

Percentages may exceed 100% where more than one practice is used on the same crop area.

The pest management practices included in the indicator are assumed to pose fewer risks to human health and the environment than 'conventional' pesticide application methods and they can potentially be applied to manage pest pressures without affecting farm profitability. The definitions of practices need to be harmonised to improve international comparability and the data availability needs to be improved.

In general it can be assumed that an increase in agricultural area under non-chemical pest control methods is good for the environment. However, some caution is required with such an interpretation, as it will be necessary to link these farm management practices to actual environmental outcomes, or outcomes measured through other indicators such as soil and water quality, biodiversity and wildlife habitats.

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