WEEDS, BUGS AND OTHER

PEST

Vertebrate Pest: organisms with backbonesIncludes fish, amphibians, reptiles, birds and

mammals. Most damaging to crops are birds and mammals

Birds: harbor pathogens Eat or damage crops Damage buildings Too much damage

Rodents: mammals that interfere with people or cause harm to crops.

Any animal out of place: deer, dogs, livestock

Pest: Rats, mice, squirrels, rock chucks moles

InsectsInsects need food and we share the food chain with themWe consider them the enemy because they want what we wantInsects are our chief rival for the world’s food supplyMost of the damage done to plants is directly or indirectly from their attempts to secure food.Some insects prefer living tissue while others prefer dead.

Beneficial Insects: insects that help mankind by pollinating, providing food and other helpful materials.

Ways that insects harm plants:Chewing of plant parts-leaves, roots, stems,

bark, flowers or fruit.Sucking sap from plant partsBoring holes between the surfaces of leaves or

other plant partsLaying eggs in some parts of the plantUsing parts of plants for their shelter or nestsCarrying other insects to the plant and

establishing them there.Allowing disease pathogens entrance to the

plant by inflicting wounds and openings.

Poisonous Insects

Insect Anatomy and DevelopmentEvery insect has an exoskeleton-protection and support

The exoskeleton is divided into three areas: head, thorax, abdomen

The antenna are located at the head and act as sensory organs

Three pairs of legs are attached at the thorax

Wings (1 or 2 pairs) are present in most species and provide ease of mobility.

Mouths are designed for either chewing or sucking

Metamorphosis: insect growth process

Two types: gradual and complete

Gradual metamorphosis consist of three life stages: egg, nymph and adult.

Complete metamorphosis consist of four life stages: egg, larva, pupa and adult

Complete Metamorphosis

Gradual Metamorphosis

Insect ControlFour types: physical, cultural, biological and chemical

Physical control: direct removal of insects by interrupting their physiological processes, prevention of entry into an area or physically destroying them with machinery.

Light at night interrupts insect behaviorHigh temperatures can kill insects in stored grainLow temperatures prevent insect attacks on fur and fabricAluminum foil, screens, trenches, sticky bands, and traps

can be used as barriers to keep insects out. Cultural control: prevents pest damage

Use crop rotation to interrupt the insect’s food supplyTill the soil and remove crop residue to reduce food supplyPlant early or later to lessen the amount of food available

when insects are in the larval stages.Use resistant varieties and strains of plantsDestroy weeds that may act as a host plant or shelter for Iinsects

Biological Control: the use of other insects or pathogens to control insects.

Some parasites deposit eggs on their victim-the larva then consumes the pest and then the adult parasite emerges from the insect mummy. Or predator insects kill and consume the pest insects.

Spotted alfalfa controlled by a parasitic wasp

Purple scale of oranges controlled by wasp

Assassin bugs suck life fluids from pink boil worms

Lady bird beetles and their larvae eat aphids

Vedalia beetles have been imported from Australia to control cottony-cushion scale in California and Florida citrus.

Pathogens can also be used to control insect pest.

Bacteria Bascillus thuringiensis kills butterfly and moth larva

Use of spores of brown, red and yellow fungi to control scale on Florida citrus.

PesticidesPesticide: a substance used for destroying insects or other organisms harmful to cultivated plants or to animals.

Today, using pesticides is very controversial and some are completely against it while others say that today’s agriculture will not survive without it.

Agriculture is charged with feeding the world. Must produce more and more with less and less land to do it on.

With EPA looking over the grower’s shoulder, the benefits of using pesticide far out weigh the risks.

Increase in crop quantity and quality are two of the major benefits of using pesticides.

A little History… Sulfur and arsenic were two of the first elements

used for pesticide. The Chinese combined these elements to make an

arsenic-sulfide chemical compound and used it as pest control compound.

Inorganic Compounds (do not contain carbon) were used until the late 1930’s.

Organic Compounds (contain carbon) are mostly produced synthetically.

Three major types of pesticides: herbicides, insecticides and fungicides.

The EPA (Environmental Protection Agency) is charged with research, deployment and management of ALL pesticides and licensing applicators.

HerbicidesHerbicide: a substance or preparation for killing plants, especially weeds.

Several different types that are grouped according to application method, type of control and chemical structure.

Selective Herbicides: selectively kills or effects only a certain type or groups of plants. Different herbicide chemistry, formulation and concentration

Different plant age, structure, growth rate and plant physiology

Environmental differences such as temperature, rainfall and soil type

Some examples:Grass killerBroadleaf killer

Nonselective Herbicides: a herbicide that kills all plants. Examples would include ground sterilants.

Contact Herbicides: herbicides that can only effect what they come in contact with. These are simple herbicides that are used to control annual weeds.

Systemic Herbicides: moves through the plant to kill from the inside out. Effectively kills the whole plant.

Preemergence Herbicides: Applied before weed or crop seeds germinate.

Postemergene Herbicides: Applied after the weed or crop is actively growing.

Chemical Families of HerbicidesChemical Herbicides: chemicals used to control weeds.Grouped by the way the chemicals adversely effect plant growth…or mode of action.

Acetanilides: interfere with cell division and protein synthesis.Preemergent or preplant applicationUsed to control annual grasses and some annual broadleaf

weeds.Dinitroanilines: act on root tissue, preventing root development in seedling plants. Preemergent application to prevent germinationThis should be incorporated into soil

Phenoxys: over-stimulates growth.Postemergent for broadleaf weeds in grasses

Triazines: photosynthetic inhibitor. Preemergent applicationUsed on annual and broadleaf weeds

InsecticidesChemicals used to control insectsClassification is based on chemical structure and/or mode of

actionBotanical, inorganic and oil insecticides are the three types.Chemical example is sulfur, is used to control mites. Discovered

thousands of years ago. Botanical example for pesticide by inhibiting respiratory

metabolism and nerve transmission is Rotenone. This is found in the roots of certain legumes. It acts as a contact and stomach poison. Used with vegetables to kill several types of insects.

Oils are highly refined oils used mostly in trees. These oils basically suffocateUse started in citrus orchardsSynthetic insecticides are man-made to effect nervous systems

Many of these are outlawed for use in US due to effect on humansMany still used today but the rules of application are strictly enforced

and precautions must be taken to be sure humans are not effected.

FungicidesChemicals used to control plant diseases caused by fungiProtectant FungicideApplied before disease infectionProvides a chemical barrier between the host plant and the

fungi poresMust be reapplied to stay effective

Eradicant FungicideApplied after the infection happensWorks systemically and travels through the plant to the

infectionLast longer then protectant fungicides

Chemical StructureInorganic: Elements used for fungicide. Sulfur, copper,

mercury, cadmium and mixtures of these.Organic: Products used that are effective but have minimal

effect on the environment.