This myth is not only false but dangerous. Doubling or tripling the dose of any garden chemical can have disastrous results. Weed killers used in this manner can injure plants (turf) you never intended to harm, not to mention leaving potentially long-lived residues in the soil. Over-use of insecticides may kill beneficial insects, harm plants, and render vegetables unfit for consumption. Doubling the recommended rate of any pesticide increases the chances of poisoning people by inhalation, absorption through the skin, and by other routes.
Fertilizers used too heavily may burn plants, prevent seed germination, and contaminate water resources. Even organic fertilizers such as manure can cause harm if you use too much.
When using garden chemicals (pesticides and fertilizers) remember that the label is the law and read and follow all label instructions
