Pesticide Basics

Elemental sulfur, still used today, was one of the earliest known pesticides. Sodium chloride, or salt, was also used as a weed killer and remains a viable option. Other early pesticides included mercury, lead, and arsenic, which were used around 600 years ago. The use of plant extracts as pesticides began in the late 1800s and early 1900s. Pyrethrum, neem, and rotenone are still used today due to their effectiveness and relatively low toxicity. Nicotine-sulfur compounds and citronella were also used during this time period. Petroleum products, such as oils, soaps, and kerosene, were used as pesticides and are still used today in some form. Gases, including cyanide and methyl bromide, were also used as pesticides but have largely been phased out due to their toxicity and environmental impact. The development of synthetic organic pesticides began in 1939 with the introduction of DDT, followed by other chlorinated hydrocarbons. These pesticides were developed to control pests, particularly mosquitoes that spread malaria and yellow fever during World War II. However, the widespread use of these pesticides led to unexpected problems, including the need for increasingly large amounts of pesticide to achieve the same level of pest control. This led to the decline of American eagle populations and the contamination of blood samples from Eskimos in the Arctic with DDT. A pesticide is a complex substance that typically consists of an active ingredient, which is responsible for killing the pest, a surfactant that helps the pesticide stick to the pest or plant, and sometimes a synergist that enhances the pesticide's action. The pesticide is often carried by a substance such as water, oil, or a solvent. Understanding the composition and properties of pesticides is crucial for effective pest control and minimizing the risks associated with their use.