Pesticides are chemicals used to control a pest. There are many types of pesticides. Herbicides kill plants, disinfectants remove germs, fungicides kill fungi, insecticides kill insects and repellents repel pests. Many other pesticides control other arthropods, birds, fish, mammals, bacteria and viruses. This video will focus on the most commonly used pesticides, herbicides, insecticides, fungicides and bactericides, and some other basic mode of action. Mode of action is the way a pesticide exerts a toxic effect on the target plant, animal or microorganism. Pesticide mode of action can be divided into two categories; systemic and contact. Systemic involves the pesticide penetrating the plant or animal and translocating within its system with the intent to protect it from bacteria, viruses or other pests. In plants, it trans-locates throughout the plant and kills the leaves and also the root system. Contact pesticides do not penetrate the host while controlling the pests. It acts as a barrier or repellent in a plant or by killing any green tissue present. Broad spectrum pesticides can kill or harm a wide variety of organisms, both beneficial and harmful pests. Then there are those that target a specific trait in a pest. Herbicides are pesticides used to control or kill unwanted plants. There are close to 5,000 herbicides registered for use in the United States, all with various mode of actions and formulations. In this video, we will cover five groups of herbicides. Those are auxins, enzyme blockers, photosynthetic inhibitors, amino acids and cell growth inhibitors. Growth regulators are commonly referred to as synthetic toxins. These chemicals mimic natural plant hormones and interrupt plant cell growth in newly forming stems and leaves. They affect protein production in normal cell division leading to malformed growth. Synthetic auxins also kill plants by causing the cells in the tissue that carry water and nutrients to divide and grow without stopping. This is often called growing itself to death, which is seen by one side of the stem being longer than the other. Sulfonylurea, phenyl pyrazoline and imidazolinone are examples of ALS inhibitors or enzyme blockers. They are chemicals that block the normal function of an enzyme called acetolactate synthase or ALS. This enzyme is essential in amino acids or protein synthesis. Without proteins, plants starve to death. Enzyme blockers kill a wide range of plants including broad leaf weeds, nutsedges and grasses. ACCase inhibitors mainly kill grasses. This enzyme helps the formation of lipids or fats in the roots of grass plants. Without lipids, susceptible weeds die. Photosynthetic inhibitors such as bipyridinium and triazine are chemicals that interfere with photosynthesis, a plant’s natural ability to make food, and disrupt plant growth ultimately leading to death. There are also amino acids synthesis inhibitors, shoot and root growth inhibitors and PPO inhibitors. Several herbicides fall into these groups including glyphosate, acetochlor and trifluralin. These herbicides stop or interrupt cell growth and division. Pigment inhibitors or bleachers are herbicides that cause the tissue of a plant to turn white after treatment. Examples include isoxazolidonone, isaxozole and triketone. They interrupt the chlorophyll production in the plant, turning the plant tissue white and erupting photosynthesis. The photosynthesis system can easily be damaged by sunlight without carotenoids. Insecticides control insects and other arthropods. Nerve and muscle poisons and insecticides disrupt, inhibit, block, terminate or activate various channels, enzymes and receptors within pests. Examples include carbamates, organophosphates, pyrethroids, pyrethrins, fipronil, chlordane, DDT and neonicotinoids. This results in a range of symptoms such as paralysis, hyper excitation, system shutdowns and overly stimulated muscle contraction. Midgut poisons are poisons that attack the guts of insects, via protein toxins leading to unbalanced ions or salts and other minerals, and septicemia or blood poisoning. Examples include Bt toxins such as Bacillus thuringiensis and Bacillus sphaericus. Insect growth regulators inhibit the normal life-cycle of insects by copying one of these hormones, directly in erupting cuticle development or lessen fat building. These would make insects die from staying in the immature life stage indefinitely. Respirators can be inhibitors of mitochondrial ATP synthase, uncouplers of oxidative phosphorylation via disruption of the proton gradient or mitochondrial complex electron transport inhibitors. These insecticides stop the insect from functioning by reducing the energy output that controls the cellular processes. Examples of this are muscle weakness, breathing issues, visual issues and loss of muscle coordination. Other unknown or non-specific target insecticides are known to affect less well-described target sites or functions or to act non-specifically on multiple targets.