Ahmed Dabo Lethal concentration (LC50) is used to measure the acute toxicity of pure active ingredients of pesticide for the target organism.

Recommended rate of pesticide application (KG or L per ha, KG/L per ton) is the amount of commercial product (active ingredient + additives) recommended for profitable and safe use in plant pest/disease/weed control based on field trials.

LC50 is measured in controlled conditions when ALL target organisms are affected by the same concentration of the poison.

In field, only very small part of the applied pesticide is affecting its target. I remember a figure about 1 part : 10000 applied parts, but not sure.

You can ask Prof. Dr. Mohamed awad