Aphid Infestation Score Calculator

Calculate the economic injury level (EIL) and economic threshold (ET) to determine when pest control treatment is cost-justified.

Control cost ($/acre)

Crop value ($/unit yield)

Injury per pest (yield units)

Damage coefficient (0-1)

Treatment efficacy (0-1)

Current pest density (per sample)

Tab to move between fields

Economic Injury Level (pests/sample)

3,529.41

Economic Threshold (pests/sample)

2,647.06

Current density as % of EIL0.57

Treatment recommended (0/1)0

Current yield loss value ($/acre)$0.10

Net benefit of treatment ($/acre)-$14.91

Value Saved At EIL15

How to Use This Calculator

Enter Control cost ($/acre), Crop value ($/unit yield), and Injury per pest (yield units).
Set Damage coefficient (0-1), Treatment efficacy (0-1), and Current pest density (per sample).
Review Economic Injury Level (pests/sample) and Economic Threshold (pests/sample).
Use Current density as % of EIL and Treatment recommended (0/1) to inform your decision.

How the result changes with Crop value ($/unit yield)

Crop value ($/unit yield)	Economic Injury Level (pests/sample)	Economic Threshold (pests/sample)
1,000	17.65	13.24
3,500	5.04	3.78
6,500	2.71	2.04
9,000	1.96	1.47

Control cost ($/acre): Cost of pesticide application per acre (product + application).
Crop value ($/unit yield): Market value per unit of produce (bushel, lb, etc.).
Injury per pest (yield units): Yield loss units caused by one pest individual (e.g., 0.02 bushels per aphid).
Damage coefficient (0-1): Proportional yield loss per injury unit. Higher = more destructive pest.
Treatment efficacy (0-1): Proportion of pest population killed by treatment (0.85 = 85% kill rate).
Current pest density (per sample): Current average pest count per sample unit from field scouting.

Economic Injury Level (pests/sample): Pest density where crop damage cost equals control cost. Treatment at this level breaks even.
Economic Threshold (pests/sample): Action threshold (75% of EIL) — treat at this level to prevent reaching EIL.
Current density as % of EIL: How close current pest levels are to the economic injury level.
Treatment recommended (0/1): 1 = current density exceeds economic threshold, treatment recommended.
Current yield loss value ($/acre): Estimated dollar value of yield loss at the current pest density.
Net benefit of treatment ($/acre): Positive value means treatment is economically justified at current pest density.

Identify Input Parameters
4 parameters
Control cost ($/acre) = 15, Crop value ($/unit yield) = 5, Injury per pest (yield units) = 0.02, Damage coefficient (0-1) = 0.05 = 6 input(s) provided
Calculate Economic Injury Level
Economic Injury Level = controlCost / denominator
3529.41 = 3529.41
Calculate Economic Threshold
Economic Threshold = eil * 0.75
2647.06 = 2647.06
Calculate Current density as % of EIL
Current density as % of EIL = (currentDensity / eil) * 100
0.57 = 0.57
Calculate Treatment recommended
Treatment recommended
0 = 0