THE EFFECTS PESTS AND DISEASES HAVE ON PLANT GROWTH?

Environmental Factors

QUESTIONS?QUESTIONS?

DISEASE AND INSECTS ON PLANTS

Damage caused by pests consists of: Holes in the leaves Damage to the

vascular tissue Attack to the fruit Contamination of the

plant Loss of nutrients Damage to the land Death of the plant

How damage affects the producer: Reduced yields Lower quality Increases production

costs Provides hiding

places for other pests Restricts marketing

Pests can injure plants in many ways. The damages can result in losses for the producers.

IDENTIFYING THE AFFECTED IDENTIFYING THE AFFECTED PLANTPLANT The first step in diagnosing a plant problem is

identifying the plant that is affected.

Identifying the plant helps narrow the list of possible causes considerably. A species will often have the same problem repeatedly.

With this knowledge, one can diagnose the problem given the plant name and symptoms.

DETERMINING THE DETERMINING THE CAUSE OF THE CAUSE OF THE PROBLEMPROBLEM Once you identify the plant that is affected,

then you can determine the cause. Plant problems are caused by two conditions.

Biological (Biotic) Environmental Conditions (Abiotic)

Biological – Organisms that include insects, rodents, and microorganisms, such as bacteria, viruses, and fungi.

Environmental Conditions – Include heat, drought, cold, etc…

IDENTIFYING THE AFFECTED IDENTIFYING THE AFFECTED PLANTPLANT How can we determine if the problem is

Biotic or Abiotic in origin?

Examine the plant closely because they both cause specific problems.

See if something is gained or something is missing. – Look for evidence that helps distinguish between the two.

Once the problem is discovered the necessary treatments can be taken

BIOTIC – LIVING BIOTIC – LIVING ORGANISMSORGANISMS Damage to plants by insects and related pests is

almost always from feeding in two ways: Chewing Sucking

Chewing – Pests such as larvae (caterpillars & grubs), grasshoppers, boring insects, snails and beetles. These pests eat plant parts and become a major problem

as they mature Easy to identify – insects may be present or holes are

found in leaves, stems and/or roots.

BIOTIC – LIVING BIOTIC – LIVING ORGANISMSORGANISMS If chewing pests are suspected, inspect the

plant to determine the insect causing the damage.

Under the leaves, near buds and feeding site, as well as the soil should be inspected.

Many pests are not present during day, so inspection should take place after dark.

BIOTIC – LIVING BIOTIC – LIVING ORGANISMSORGANISMS Sucking – Pests that feed on the sap by inserting

their mouthparts into the phloem or by feeding on sap from wounds.

Pests such as aphids, scales, mites, whiteflies, thrips, etc…

Diagnosis is more difficult Usually small and varies in damage Symptoms include puckering (cupping) or bleaching of

the leaves.

DETERMINE THE CAUSE DETERMINE THE CAUSE OF THE PROBLEMOF THE PROBLEM

Caterpillar Grubs/Bores Leaf Miners Grasshoppers Beetles Snails/Slugs Earwigs

Aphids Scale Whiteflies Mealybugs Mites Thrips

CHEWING SUCKING

BIOTIC- BIOTIC- MICROORGANISMSMICROORGANISMS Another organism that damages the plants

are microorganisms

Cause diseases that kill the foliage or rot the root system.

Divided into three types; Fungi Bacteria Viruses

BIOTIC -BIOTIC -

MICROORGANISMSMICROORGANISMS Fungi – single or multi-celled organism that lacks

chlorophyll Rely on sources for food and energy Responsible for more plant diseases Easy treated

Common Fungus diseases of plants Mildew Wilt Rot Leaf spot Rust Canker Smut Blight

BIOTIC -BIOTIC -

MICROORGANISMSMICROORGANISMS Bacteria – single celled organism, usually

lack chlorophyll, and grows in colonies Spread by splashing water or contaminated tools Responsible for few plant diseases Difficult to treated

Viruses – not alive and not referred as microorganisms Spread among plants by pests and hum

Viruses: Stunt Curly Top Mosaic Yellows

ABIOTIC – ENVIRONMENTAL ABIOTIC – ENVIRONMENTAL CONDITIONSCONDITIONS Frost Damage - differs according to age and

specie Young tissue is more tender Woody plants are more resistant Symptom – overnight wilting (uppermost

leaves and buds) Winterkill – is the partial or total death due

to cold temperatures. Complete winterkill both tops and roots die Manifest “burning” of evergreens – leaves turn

brown, causing the tree to be marred.

ABIOTIC – ENVIRONMENTAL ABIOTIC – ENVIRONMENTAL CONDITIONSCONDITIONS Drought – Occurs due to the lack of water

Wilting is the main symptom Drought-struck plants will revive unless leaves are

leathery and crisp Many will regenerate from roots

Poor Drainage & Flooding – In which roots remain in water (saturated soil) Plants die due to the lack of oxygen Many will tolerate occasional flooding

ABIOTIC – ENVIRONMENTAL ABIOTIC – ENVIRONMENTAL CONDITIONSCONDITIONS Lack of Soil Nutrients

Will not kill plants, but stunt and bleach Symptoms vary with each specie –required amount

of elements 80% of deficiencies are lack nitrogen, phosphorous,

and potassium. However, in Utah – potassium is readily deficient, due to our soil type.

ABIOTIC – ENVIRONMENTAL ABIOTIC – ENVIRONMENTAL CONDITIONSCONDITIONS Unavailability of Nutrients – pH –Plants

that are unable to absorb the essential elements due to high or low pH. Iron and Manganese are the most effected by pH

UNAVAILABILITY OF NUTRIENTS – PH

ABIOTIC – ENVIRONMENTAL ABIOTIC – ENVIRONMENTAL CONDITIONSCONDITIONS Excess Soil Salt – An excess of a nutrient

buildup in the soil Wilting and browning will occur Similar to signs of drought Cured by leaching

Heat Scorch- Due to reflection of sun-generated heat from surfaces Higher on south-facing walls Leaf margins and veins turn brown Tolerance varies among species

ABIOTIC – ENVIRONMENTAL ABIOTIC – ENVIRONMENTAL CONDITIONSCONDITIONS Soil Compaction – the compacting of soil

due to high traffic areas Air space is compressed Air & water absorption is inhibited Slows plants grow – extreme cases plants may

die

ABIOTIC – ENVIRONMENTAL ABIOTIC – ENVIRONMENTAL CONDITIONSCONDITIONS Improperly Applied Chemicals – Injure to

plants when chemicals are applied in excessive amounts or to the wrong specie. 2, 4-D is the most frequent killer Spray drift can also cause distorting and curling

of the plant

ABIOTIC – ENVIRONMENTAL ABIOTIC – ENVIRONMENTAL CONDITIONSCONDITIONS Grade Changes – Raising soil levels over

roots more than a few inches. Water and oxygen are restricted Tree wells are necessary

Air Pollution – Problem in few areas Affects susceptible plants – cone bearing

evergreens Damage occurs in many forms

Browning or death of foliage

TREATING PLANT TREATING PLANT DISORDERSDISORDERS To restore a plant to its healthy state it depends

on the condition (Abiotic or biotic). Abiotic – Correct the condition or find a plant

that will tolerate the situation Biotic – Find plants that are not susceptible or

keep plants healthy or use an integrated pest management approach. IPM (Integrated Pest Management)

Identification (plant and pest) Damage to plant (location) Sanitation Control Physical/Cultural Control Biological Control Chemical Control

The basis of an IPM program is to predict the problem and formulate a control plan.

INTEGRATED PEST INTEGRATED PEST MANAGEMENT MANAGEMENT The current, most widely accepted approach

to pest management is integrated pest management (IPM). Pests are recognized as a part of the crop

ecosystem.

The goal is to reduce damage to a low level.

Below the economic threshold, above which injurycannot be tolerated and controls must be used.

When this action threshold of damage is reached, control measures are taken.

INTEGRATED PEST INTEGRATED PEST MANAGEMENT MANAGEMENT While difficult for a gardener to be familiar with

the life cycles of all the insects and diseases of plants, he/she can use integrated pest management to a limited extent: Decide whether it is due to an insect, disease,

rodent, nutritional deficiency, or other source.

Determine whether the harm being done is sufficientto justify control—set a level of tolerable damage. Treatment might not be justified at all.

Use cultural/biological controls, if practical &available.

Apply a pesticide as a last resort, or if the only available control.

INTEGRATED PEST INTEGRATED PEST MANAGEMENT MANAGEMENT Identification (plant & pest) - Before deciding

to take any control action, you must correctly identify the plant infected and the pest causing harm. Learn pest and host life cycle, anatomy, biology,

color, shape, mouthpart (chewing or sucking), and size. Often, other stages of the life cycle are susceptible to preventative actions.

Life cycle: The way the pest develop, grow and change. Complete Metamorphosis Incomplete Metamorphosis

INTEGRATED PEST INTEGRATED PEST MANAGEMENT MANAGEMENT Complete Metamorphosis – Has four

changes of growth and development.

Egg Larvae Pupa Adult

Knowing what to look for can help identify the insect

INTEGRATED PEST INTEGRATED PEST MANAGEMENT MANAGEMENT Incomplete Metamorphosis – Has three

stages of growth and development.

Egg Nymph Adult

INTEGRATED PEST INTEGRATED PEST MANAGEMENT MANAGEMENT Damage (location) – To identify the location of

the damaged tissue can help narrow the pest. Damage parts:

Leaves (top and bottom) Roots Stems Buds Fruit

This will help again indentify the pest as a chewing, sucking or disease.

INTEGRATED PEST INTEGRATED PEST MANAGEMENT MANAGEMENT Sanitation – Involves removing diseased

plant material or harboring plant material. Reduces the pest population Weeds and leaves should be removed

INTEGRATED PEST INTEGRATED PEST MANAGEMENT MANAGEMENT Physical Control – Method that physically

prevents activity of pests and diseases. Pruning – A control technique to control

localized diseases – gall, wilt, canker, and blight

Rouging – Removing diseased plants to stop spreading. Valuable for annuals Controls only viruses and bacteria

Crop Rotation – Planting a different specie in an area each year Valuable control for soil-pathogens

INTEGRATED PEST INTEGRATED PEST MANAGEMENT MANAGEMENT PHYSICAL CONTROL – PHYSICAL CONTROL – CONTINUED….CONTINUED…. Planting Resistant Species – One of the

best control methods Many plants have resistance to diseases

Plant Selection and Culture – Selection of plants that are not generally affected by diseases, as well as are adaptable to the climate (environment)

INTEGRATED PEST INTEGRATED PEST MANAGEMENT MANAGEMENT Biological Control - Involves the use of

beneficial living organisms to control pests (Microbial, parasitic, or predators organisms).

Advantages:

Considered environmentally safe – no use of chemicals

Does not create new pest problems Pest cannot develop resistance

Disadvantages: Very narrow host range Process is slow Does not eradicate pest Expensive and requires supervision

INTEGRATED PEST INTEGRATED PEST MANAGEMENT MANAGEMENT Chemical Control - methods involve the use of

chemicals such as poisons, growth regulators, sterilants, and attractants and repellants to control pests. Used when all other factors are useless Should be specific to the pest Used when outbreaks are severe

Chemical controls:

Insecticides Miticides Fungicide Bactericide Herbicide Pesticides

INTEGRATED PEST INTEGRATED PEST MANAGEMENT MANAGEMENT CHEMICAL CONTROL, CHEMICAL CONTROL, CONTINUED…CONTINUED… There are various chemical control methods.

Sprays – kill on contact or are absorbed

Soil Drenches – Contact or systemic underground

Systemic – absorbed in the plant and kill pest that feed on the plant

Baits – Stomach poisons

Repellants – products applied to plant to repel insect.

CHOOSING CHEMICAL CHOOSING CHEMICAL CONTROLSCONTROLS

Select chemicals that will control pests satisfactorily. As nontoxic as possible to people & beneficial organisms.

CHOOSING CHEMICAL CHOOSING CHEMICAL CONTROLCONTROL

Table 7-4 lists the LD50 of many common insecticides, fungicides, and bactericides. The “lethal dose killing 50% of a population.”

Expressed in milligrams per kilogram of total body weight.

Pesticides with different modes of action shouldbe rotated to avoid resistance. The mode of action is the way it kills the pest.

Rotating between insecticides with different modesof action, resistance development is slowed & betterpest management results are obtained.

SAFE USE OF CHEMICAL SAFE USE OF CHEMICAL CONTROLSCONTROLS

Rules to observe:

Use chemical only when needed. Select the least toxic Read the label carefully Wear protective clothing when mixing and applying

chemicals Apply when weather is good (not to hot or windy) Apply the amount specified Apply complete coverage Use good conditioned and appropriate equipment Dispose of chemical properly Label holding tank and treated crops with the name of

the chemical used.

SAFE USE OF SAFE USE OF CHEMICAL CONTROLSCHEMICAL CONTROLS