Pesticides

Chemicals used to control or manage pest populations

What is the purpose of pesticides?

To reduce pest populations to a non-economic level

Pests

Plants and animals that compete with man for food and fiber, or attack man directly

Examples of pesticides:

Insecticide, Acaricide, Herbicide, Fungicide, Nematicide, Rodenticide, Piscicide, Avicide, and Repellents

Insecticide

kills insects

Acaricide

kills mites-ticks

Herbicide

kills weeds

Fungicide

kills fungus

Nematicide

kills nematodes

Rodenticide

kills rats/mice

Piscicide

kills trash fish

Avicide

affects birds

Repellents

repels birds

Pesticide Categories:

Non-persistent, Persistent, Accumulative

Non-persistent

breaks down quickly to harmless or less harmful products

Persistent

breaks down slowly and may remain in the environment for long periods of time. generally, more harmful to non-target species

Accumulative

may build up in the bodies of animals in food chains, including man

Examples of non-persistent pesticides:

organosphate and carbmate pesticides

Examples of persistent pesticides:

Organochlorine pesticides, 2-4 D

Examples of accumulative pesticides:

DDT, dieldrin, heptachlor, aldrin, toxaphene

How do pesticides harm the environment?

Injure plants, illegal residues, direct mortality, chronic exposure hazards, chronic effects of pesticides

How do pesticides harm the environment? Injure plants

Phytotoxicity

How do pesticides harm the environment? Illegal residues

Loss of Sale

How do pesticides harm the environment? Direct Mortality

Acute Toxicity of Non-target species insects- beneficials, predators, parasites, fish food Fish- nearby water Birds- in & around target area Man accidentally (improper use)

How do pesticides harm the environment? Chronic Exposure Hazards

Carcinogenicity, Teratogenicity, Mutagenicity, Reproductive Problems- Birds (eggshell thinning in sensitive species), Fish- Trout reproduction, Limit soil use, Limit water use

Carcinogenicity

the potential to cause cancer

Teratogenicity

may cause birth defects

How do pesticides harm the environment? Chronic effects of Pesticides

long term exposure to sublethal levels may be more important than acute mortality due to a single exposure

Pesticide Movement:

Drift, Erosion, Leaching, Volatilization, Codistillation, Streams, Air, Animals

Pesticide Movement: Drift

Problem when off target - droplet size: smaller droplets are more effective for pest control, use when less than 5 mph wind

Pesticide Movement: Erosion

Wind and Water - most pesticides are absorbed on soil particles or organic matter in the soil

Pesticide Movement: leaching

little movement

Pesticide Movement: Codistillation

soil and water

Pesticide Movement: streams

sediment

Pesticide Movement: Air

global movement

Pesticide Movement: Animals

residues

Basic ingredients of life:

Soil, Air, Water, Sunlight

Effects of soil pollution:

Sterilization, Limit Use

Sources of Contamination:

Direct applications, indirect - plants and animals

Persistence in soil:

insecticide itself, soil type, moisture, microorganisms, soil temperature, cover crops, cultivation, mode of action, formulation, translocation

Persistence in soil: Insecticide itself

half-life of a persistent pesticide (DDT) may be in the soil for several years

Persistence in soil: Soil type

Heavy soils tend to increase persistence as compared to sandy or light soils. Higher rate for heavy clay soils.

Persistence in soil: Moisture

generally increases the breakdown of pesticides and lessens their persistence. Increases volatization and codistillation

Persistence in soil: Microorganisms

also degrade pesticides

Persistence in soil: Soil temperature

increasing soil temperature increases volitization, codistillation, and degradation of persistence.

Persistence in soil: cover crops

increase persistence

Persistence in soil: cultivation

decreases persistence

Persistence in soil: formulation

granules more persistent than sprays

Persistence in soil: Translocation

a device used purposely to control certain pests with systemic pesticides - removes some residues from the soil into the plants

____ commonly will contain residues amounting to ___ of the soil level of organochlorine insecticides

Soybeans; 10%

Water sources of contamination

Direct Application, Accidental Application and Drift, Runoff from Treated Areas, Waste from Manufacturing, Leaching, Pesticide Containers, Sewage, Concern

Water sources of contamination: Direct Application

made to water to control or manage pests like trash fish, noxious weeds, mosquito larvae, etc.

Water sources of contamination: Accidental Application and Drift

aerial applications to crops near streams and lakes sometimes results in accidental direct applications and drift

Water sources of contamination: Runoff from Treated Areas

carries both water soluble and insoluble pesticides into drainage systems

Water sources of contamination: Waste from Manufacturing

happens occasionally

Water sources of contamination: leaching

into subsurface water an area of concern

Water sources of contamination: Pesticide Containers

sometimes wash into lakes and streams, many placed deliberately

Water sources of contamination: Sewage

from towns and cities

Water sources of contamination: Concern

acute toxicity of some pesticides to fish

Air sources of contamination:

Drift, Volatilization, Codistillation, Dust deposited through rain or dust, More than one pesticide, Synergistic reaction, Antagonistic reaction

Drift

Air sources of contamination: during application process

Volatilization

Air sources of contamination: from soil, plant, animal, and water surfaces.

Codistillation

Air sources of contamination: with water

Dust deposited through rain or dust

Air sources of contamination: globally

More than one pesticide

Air sources of contamination: frequently used to control a complex of pests - check label for compatibility

Synergistic reaction

Air sources of contamination: two or more chemicals give activity exceeding that which would have been normally expected

Antagonistic reaction

Air sources of contamination: two or more chemicals exert activity below or less than that which would have been expected