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A Method to Measure the Environmental Impact of Pesticides

EIQ Field Use Rating

Once an EIQ value has been established for the active ingredient of each pesticide, field use calculations can begin. To accurately compare pesticides and pest management strategies, the dose, the formulation or percent active ingredient of the product, and the frequency of application of each pesticide need to be determined. To account for different formulations of the same active ingredient and different use patterns, a simple equation called the EIQ Field Use Rating was developed. This rating is calculated by multiplying the EIQ value for the specific chemical obtained in the tables by the percent active ingredient in the formulation by the rate per acre used (usually in pints or pounds of formulated product).

EIQ Field Use Rating = EIQ x % active ingredient x Rate

With this method, comparisons of environmental impact between pesticides and different pest management programs can be made. For example, if several pesticides can be used against a particular pest, which pesticide is the least toxic choice? Table 5 shows an example comparing the environmental impact of three insecticides: carbaryl (Sevin 50WP), endosulfan (Thiodan 50WP), and azinphos-methyl (Guthion 35WP). Although carbaryl has a lower EIQ (22.6) than endosulfan (40.5) or azinphos-methyl (43.1), it may take more of it to provide equivalent control. For example, 6 lbs/acre of Sevin may provide the same level of control of a certain pest as 3 lbs/acre of Thiodan or 2.2 lbs/acre of Guthion. In this situation, Guthion would have the lowest EIQ Field Use Rating (33 .2) and would be the least toxic choice. Thiodan (60.8) would be the second choice and Sevin (67.8) would be the last.

By applying the EIQ Field Use Rating, comparisons can be made between different pest management strategies or programs. To compare different pest management programs, EIQ Field Use Ratings and number of applications throughout the season are determined for each pesticide. and these values are then summed to determine the total seasonal environmental impact of the particular strategy. Table 6 compares the theoretical environmental impact of several different pest management approaches that have been used in research projects to grow 'Red Delicious' apples in New York. In this example, a traditional pest management approach to growing 'Red Delicious' apples that does not rely heavily on pest monitoring methods would result in a total theoretical environmental impact of 938 due to pesticides. An IPM approach that incorporates pest monitoring methods, biological control, and least toxic pesticides would have an environmental impact of only 167. The organic pest management approach, which uses only naturally occurring pesticides, would have a theoretical environmental impact of 1,799 according to the model. The environmental impact of the latter approach is so much larger than the other strategies primarily due to the larger quantities of sulfur required and more frequent applications needed to provide the same level of control of apple scab in this variety. By using the EIQ model, it becomes possible for IPM practitioners to rapidly estimate the environmental impact of different pesticides and pest management programs before they are applied, resulting in more environmentally sensitive pest management programs being implemented.

Table 3. An example showing the EIQ field use rating of three different insecticides to determine which pesticide should be the least toxic choice.

Material

EIQ

ai

Rate

EIQ field use rating

Sevin 50WP (carbaryl)

22.6

0.50

6.0

67.8

Thiodan 50WP (endosulfan)

40.5

0.50

3.0

60.8

Guthion 35WP (azinphos-methyl)

43.1

0.35

2.2

33.2

Table 4. Theoretical environmental impact of different pest management strategies used to grow 'Red Delicious' apples in New York.

Traditional Pest Management Strategy

Material

EIQ

ai

Dose

Applications

Total

Rubigan EC

27.3

0.12

0.6

4

8

Captan 50WP

28.6

0.50

3.0

6

257

Lorsban 50WP

52.8

0.50

3.0

2

158

Thiodan 50WP

40.5

0.50

3.0

2

61

Guthion 35WP

43.1

0.35

2.2

2

66

Cygon 4E

74.0

0.43

2.0

3

191

Omite 6EC

42.7

0.68

2.0

2

116

Kelthane 35WP

29.9

0.35

4.5

1

47

Sevin 50WP

22.6

0.50

1.0

3

34

Total Environmental Impact

938

 

Integrated Pest Management (IPM) Strategy

Material

EIQ

ai

Dose

Applications

Total

Nova 40WP

41.2

0.40

0.3

4

20

Captan 50WP

28.6

0.50

3.0

1

43

Dipel 2X

13.5

0.06

1.5

3

4

Sevin 50WP

22.6

0.50

3.0

1

34

Guthion 35WP

43.1

0.35

2.2

2

66

Total Environmental Impact

167

 

Organic Pest Management Strategy

Material

EIQ

ai

Dose

Applications

Total

Sulfur

45.5

0.90

6

7

1720

Rotenone/pyrethrin

25.5

0.04

12

6

73

Ryania

55.3

0.001

58

2

6

Total Environmental Impact

1720