economic threshold concept

The economic threshold concept is most relevant for decisions that are made when the level of pest attack can be assessed through monitoring. Various measures can be used to assess the level of pest attack, such as the number of pest insects per 10 plants, the percentage of diseased plants in a crop, or the number of weeds per m2. The economic threshold, defined in terms of the level of pest attack, is the level of attack where the estimated benefits of treatment cover the cost of that treatment. If the level of attack is below the threshold, the cost of treatment would exceed the benefits and the farmer would make a loss by applying the treatment.

A simple way of looking at economic thresholds is to start with the cost of treatment. If you can estimate what it costs to apply a pest management treatment, you can then try to estimate what benefit - in terms of reduced yield loss - you would need to gain for treatment to be worthwhile.

Thus, the % crop loss necessary for treatment to be worthwhile = [C/YP(K/100)] x 100%

Where:

C = the cost of treatment,

Y = the expected yield of the crop,

P = the expected price per ton, and

K = the expected effectiveness of the treatment.

For instance, in the Philippines, it would be worth applying a herbicide for weed control if the expected yield loss (without control) was greater than 9%, where - C = 38; Y = 4.5; P = 154; K = 60