Agri-science unit 14 Pesticides
The use of pesticides is one of the success stories of agriculture in the United States. Original pesticides were organic compounds that usually Produced by plants to keep pests away. They were very selective and Did not have a long effective period. Chemists in the 1930’s and 40’s Found inorganic compounds to control mosquitoes which carried diseases Like Malaria. This interest in inorganic chemistry gave rise to the pesticide Industry to control insects, plant, and animals. Like anything else over use Has led to resistant pests, so now an integrated approach which relies on limited Use of pesticides is being promoted. With out the use of pest control and Pesticides food costs would soar and food quality would decrease. Remember That the restrictions and bans talked about in the book occur only in the US. Other countries in the world still use products such as DDT and 24D. When we Import food from other countries what are we really getting?
Herbicides are chemicals that control unwanted plants. Herbicides that affects certain types or groups of plants are called Selective herbicides. If applied to a crop the herbicide may target Only the unwanted plant not the crop. Nonselective herbicides controls or kills all plants that they are applied to. Contact herbicides affect only the part of the plant they touch. They Do not move in the plants, like from the leaves to the roots. Systemic Herbicides translocate in the plant. They may move from the Leaves to the root, or from the root to the stem. Pre-emergence pesticides can be applied to fields BEFORE the crop comes Out of the ground. This may kill unwanted plants before they compete With the crop for water, nutrients and sunlight. Some pesticides must Be applied post-emergence or after the crop has sprouted, but before a certain Growth stage.
Families of pesticides: Over 23 different families of herbicides are in production today. Each family has Its own unique chemical formula and mode of action. We will list a few of the more Common ones. Acetanilides: They affect cell division in the plant Dinitroanilines: Affect the roots of the plants Phenoxys: Over stimulate plant growth Triazines: inhibit the plants photosynthetic ability
Insecticides: Affect the insect during different stages of life cycle or some physical feature Of the insect to control them. Again organic and inorganic compounds are used To control different pests in different crops. Rotenone: Is an old organic compound which inhibits the respiratory system. It also sometimes used to clean fish out of ponds. Oils: Some super refined oils are used in specialty crops to coat the insect Spericals which are the air intake organ of the insect. Synthetic: inorganic compounds that were developed by chemists to control insects. This includes chlorinated hydrocarbons, pyrethroids, and organophosphates. They Mainly affect nerve transmission in insects. Chlorinated hydrocarbon, DDT banned after the book Silent Spring Carbanomateis most common organophosphate in use
Fungicides: Used to control diseases caused by Fungi in plants. Fungi are plant parasites That have no chlorophyll. Fungicides usually must be applied often due to fungi Reproduction. Protectant fungicides: Applied BEFORE the disease is present. Eradicant fungicide: Applied AFTER the disease is present. Labels and labeling: The label of a pesticide gives important information about the chemical, uses, Restrictions, potency, dangers, and your responsibility as a user. Some chemicals Are restricted which means that they must be used by a licensed applicator while Other chemicals are general use pesticides which may be used by the general public Without any special training (reasonable man/woman doctrine) Use classification: Some chemicals are restricted which means that they must be used by a licensed applicator while other chemicals are general use pesticides which may be used by the general public without any special training (reasonable man/woman doctrine)
Labels continued: Trade name: the name the manufacturer gives the product Formulation: physical property of active ingredient (granules, powder, etc. Common name: given to the specific product by a pesticide authority. Ingredients: percentage by weight of active and inert ingredients. Net contents: total amount of product in container. Words and symbols: what some of the words on the label mean. Danger – poison: a few drops to one teaspoon will kill a 150 pound person Warning: 1 -2 teaspoon will kill a 150 pound person Caution: more that 2 teaspoon are needed to kill a 150 pound person. LD: Lethal Dose LD50 – amount needed to kill 50% of test population given in mg of pesticide/ Kg of body weight. LC: Lethal Concentration LC50 – amount needed to kill 50% of test population given in PPM
Labels cont. Other information found on the label: Mixing and application directions Misuse statement Reentry period Storage/cleanup/disposal Always try to limit your personal exposure to chemical when mixing, applying, And cleaning up. RISK = toxicity X exposure PPE: Personal Protective Equipment: what to wear to protect yourself. Hat and coveralls: prevents direct exposure to skin. Gloves: prevent exposure to hands Goggles: prevent absorption through eyes Respirator: prevents absorption through lungs Personal Hygiene: always shower after applications and double wash hands before eating.
Storing chemicals: It is the purchasers responsibility to protect themselves and others from accidental exposure to pesticides. Keep them in a place that is LOCKED VENTILATED LABLED