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Home Garden SeminarJosephine County Master GardenersJosephine County Master Gardeners

Alternatives to PesticidesGail Langellotto

Urban and Community Horticulture Specialist

OSU Extension and Department of Horticulture

Number of Species Currently Controlled with Pesticides

Diseases 137Insects 304Mites 34Nematodes 23Weeds 102

Agricultural Effects uponDiversity Equilibrium

0

10

20

30

40

vers

ity

-40

-30

-20

-10Div

Pristine"Natural"

ConventionalAgriculture

AlternativeAgriculture

Conservation Biological Control

• Few studies have been conducted in garden systems– Exception: Shrewsbury and Raupp (2006). Do top-down

or bottom up forces determine Stephanities pyriodes in urban landscapes?p

Two Dimensional System Three Dimensional System

• Raupp et al. 2001. Plant species diversity and abundance affects the number of arthropod pests in residential landscapes.

Land

Components

AbioticPlant

Disease Complex

LandscapeEcology Pest

Complex

Land

NaturalEnemies

Management

SoilAbioticFactors

Plant Diversity

OrganicMatter

Nutrients

Soil

Nematodes

MicrobialFlora

Micro/MacroInverte-brates

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Climbing the Alternatives Ladder

Level II

Level III

Systems IntegrationSystems Integration

Regional IntegrationRegional Integration

Level I

Level II

PesticidesPesticides

Multiple TacticsMultiple Tactics

Integrated StrategiesIntegrated Strategies

MultiMulti--species / Multispecies / Multi--tactictactic

Principles of IPM

• Prevent Problems• Monitor the plants• Identify the pest organismy p g• Establish an acceptable injury

threshold• Manage using all available

strategies

Objectives

• Provide a basic understanding of how to use IPM Principles to reduce pesticide use in the home and garden.

• Reduce pesticide use by managing using all available strategies– Cultural

– Physical

– Biological

– Chemical

Manage Using All Available StrategiesManage Using All Available Strategies

Cultural

Physical

Biological

Least Toxic

Biological

Chemical

– Use a least hazardous approach, that will also enact effective control

Most Toxic

Cultural Control Prevention!

• Altering your garden or gardening practices to reduce pest populations or injury

• Reduce plant stress through proper horticultural practicehorticultural practice

• Three Components– Plant Selection

– Plant Installation

– Plant Maintenance

Plant Selection: Resistant Plants

Adult Root Weevil Damage to Leaves

R. davidsonianum

Root Weevils

Resistant varietiesList of Rhododendrons Resistant to Root Weevils can be found at:http://www.co.thurston.wa.us/health/ehcsg/pdf/weevil%20guide.pdf

Information on Managing Root Weevils in the Pacific Northwest:http://extension.oregonstate.edu/catalog/pdf/ec/ec1485.pdf

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Plant Selection: Companion planting

• Pests and the Plants that Repel Them

Flea beetle Catnip, marigold, nasturtium, peppermint, rue, spearmint, southernwood, tansy

Japanese beetle Catnip, chives, garlic, nasturtium, odorless marigold, tansy, white geranium

http://counties.cce.cornell.edu/Chemung/publications/companion-planting.pdf

white geranium

Rabbit Garlic, marigold, onion

Slugs and Snails Fennel, garlic, rosemary

Spider mite Coriander, dill

Plant Installation

• Improper planting often results in stressed plants.

• Compacted soils are often a particular problem on home sites.problem on home sites.

Planting container plants

• Container plants with circling roots or that are root-bound should have these problems corrected prior to planting.

Root Preparation Prior to Planting

• Thoroughly preparing the roots prior to planting on root-bound pots usuallybound pots usually improves growth immediately as well as plant survival

Planting container plants

• Size of planting hole

• Depth of planting

• Finish by watering the plant in well

• Time of planting

Cultural Control: Plant Maintenance

• Water for deep, spread roots

• Fertilizing– Too much fertilizer can increase insect pest

problems as much as too little fertilizer.

• Mulching / Groundcovers– Can reduce weed problems

– Avoid bringing new weeds to the garden in manure, straw

• Remove and properly dispose of garden debris

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Disease Management: Sanitation

• Clean up Debris

Physical/Mechanical Control

• Use of physical barriers, machines or objects to prevent an infestation (preventative), or kill the pest (remedial)

Horticultural fabrics to cover plants– Horticultural fabrics to cover plants (preventative)

– Flyswatter (remedial)

Physical Control of Weeds

• A sharp hoe and lots o’ diligence• Mulch!• Cover crops• Crop rotationCrop rotation • Whenever possible prevent weeds from

going to seed

Weed Management

• Weeds are easier to kill when they are very small – “white thread” to 2-3 true leaves.

• Mechanical weeding is more effective during warm, dry, windy weather. Plants can re-root in cool et eathercool wet weather.

• In the Vegetable Garden or Home Orchard-– Control weeds early in crop growth

– Cover crops can reduce subsequent weed pressure

Weed Management

• Weeds are easier to kill when they are very small – “white thread” to 2-3 true leaves.

• Mechanical weeding is more effective during warm, dry, windy weather. Plants can re-root in cool et eathercool wet weather.

• Control weeds early in crop growth

• Cover crops can reduce subsequent weed pressure

Physical Control: Sticky barrier

• Can prevent pests from climbing and colonizing tree.

• Can prevent pests from climbing down tree to pupate in soil

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Copper Barriers for Molluscs

Brown Garden Snail

Physical Control: Collars and Cages

Tin CollarCutworm Control

Plant Cage on RadishesCabbage Maggot Control

Physical Control: Row Covers

• Covers many plants, or entire rows

• Protection for seedlings, or during other lnerable timesother vulnerable times

• Light, thermal and air environment will be modified

Handpicking

Place insects in soapywater to kill them

Spray plants with water to dislodge aphids.

Aphids

Water Sprays

Spider

Mites

Spider mites

p

Must be sprayed regularly to prevent recolonization.

Aphids

Pruning

Tent caterpillars

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Boxelder Bug Flea

Vacuuming

Asian Ladybug Beetle

Tilling

Tilling

Garden symphylan

Physical Control: Bug Zappers

Royal Walnut Mothsitting on a bug zapper

Biological Control

• Biological control is the use of living organisms —parasites, predators, or pathogens—to maintain pest populations below economically damaging levels, and may be either natural (conservation) or applied (augmentative)(conservation) or applied (augmentative).

The 3 P’s:Predators, Parasitoids, Pathogens

Beneficial Aspects of Arthropods

• Pollinators – bees for cucurbits

• Food sources – part of the food chain

• Biological control agents for weeds and other insects

E h il ti• Enhance soil properties

• Aesthetic value

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Braconid emerging from moth cocoon

Ichneumonid

Ichneumonid

Parasitoid Wasps

Image Source:AMNH

Braconid pupae on tomato hornworm

Ichneumonid

Parasitoid Wasps

Eulophid Wasp

Aphelenid Wasp Encyrtid Wasp

Ptermomalid Wasp

Parasitized Insects

Aphid Mummies

Parasitized Cabbage Moth Larvae

Parasitized Beetle Larvae

Parasitoid Emerging from

Aphid Mummy

Augmentative Biological Control

• Increase local abundance of predators and parasitoids by releasing the biological control agents into the garden

• Use of biological control agents as you would a h i l ti idchemical pesticide

Stapling EggCards Egg Cards

Lacewing Eggs

Conservation Biological Control

• Increases the abundance of natural enemies where the habitat has been manipulated (Langellotto and Denno 2004)

• Spatial scale of conservation biological control area influences success (Langellotto and Rosenheim in prep)

Beetle BanksBeetle BanksHedgerow

Field Margin

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Conservation Biological Control Strategies

• Reduce Disturbance– Reduce Pesticide Use on the Lawn and in the

Garden

– Leave an area of the garden undisturbed – no or low mowing, raking or pruning

Conservation Biological Control Strategies

• Provide Basic Needs– Food

– Water

– Shelter

Insectary Plants for Biological Control

• Coreopsis, Parsnip,

• Mints

• Buckwheat

• Yarrow

• Sunflowers, Asters, Coneflowers

• Lobelia

• Goldenrod

Chemical Control in IPM

• IPM permits integrated use of chemical pesticides, but also actively seeks to minimize applications

• REDUCE – spray when needed, and not according to scheduleg

• REPLACE – use other, less toxic alternatives to pesticides

• REDESIGN – correct past landscape design issues to reduce pest problems

Organic and Synthetic

• Organic: Derived from an organic source– Botanicals (pyrethrum

NeemTM, RotenoneTM) – Microbials (Bt sprays)

Naturalytes (SpinosadTM)– Naturalytes (SpinosadTM)

• Synthetic: Manufactured pesticides

SyntheticPyrethroid

OrganicPyrethrin

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Organic Fungicides

• Horticultural oils

• Copper based

• Sulfur

Serenade ( )• Serenade (Bacillus subtilus)

• Baking soda (K)This is a peach tree grafted with two curl resistant cultivars. Cultivar 'Q 1-8' on the left and the cultivar 'Mary Jane' (with lots of curl) on the right.

Materials Allowed for Organic Disease Management- PNW Disease

Organic Pesticides

• Azadirachtin- Neem• Bt- biological• Beauveria- biological• Horticultural oils• Insecticidal soap• Iron phosphate slugs• Iron phosphate- slugs• Kaolin clay• Lime Sulfur• Pyrethrins• Rotenone• Spinosad• Sulfur

2008 PNW Insect page 389Orange = Biological

Synthetic Pesticides

Class Mode of Action

Range of Activity

Notes

Organophophates Cholinesterase Inhibitor

Broad Potential non-target effects on mammals, beneficial insects a concern

Carbamates Cholinesterase I hibit

Broad – Chewing I t

Potential non-target effects on b fi i l i tInhibitor Insects beneficial insects a concern, mammals

Pyrethroids Impacts Ion Channels

Broad Low toxicity to mammals, birds. Toxic to fish. Potential non-target effects on beneficial insects.

Neonicitinoids Impacts Ion Channels

Broad –Homoptera and beetles

Systemic. Low toxicity to mammals. Potential non-target effects on beneficial insects, especially bees.

Organic Pesticides

Class Mode of Action

Range of Activity

Notes

Microbials – Bt** Stomach poison. Paralyzes insect gut.

Narrow – (Bt-k) caterpillars, (Bt-t) beetles, (Bt-i) -Flies

Must be ingested in order to be effective. Thus, targets only those insects that are feeding on the protected plant.

Mi bi l O it L f Ch L t i it t l dMicrobial Derivitives –Spinosad**

Overexcites nervous system

Leaf Chewers, Thrips, some Gall Makers

Low toxicity to mammals and beneficial insects.

Horticultural Oils** Smothering (block spiracles)

Effective against many insects –active stages and eggs

Low toxicity and minimal impacts on non-target insects.

Insecticidal Soaps** Disrupts cuticle Small, soft-bodies insects and mites

Vertebrates and non-target insects generally not impacted. Toxic against beneficial mites. May directly harm plant

Organic Pesticides

Class Mode of Action

Range of Activity

Notes

Botanical Insecticides -pyrethrum

Impacts Ion Channels

Many insects, but particularly useful against caterpillars, sawfly larvae leaf

Low toxicity to mammals. Rapid break down in sun. Degradation limits impact on beneficial insects, but may require repeat application.

larvae, leaf beetles, leafhoppers

Botanical Insecticides - neem

Inhibits feeding, interferes with molting and egg production

Effective against a limited range of insects.

Low toxicity to mammals. Low risk to beneficial insects.

Information for Tables Taken From: Whitney Cranshaw. Classes of Pesticides Used in Landscape/Nursery

Pest Management. In Chapter 9 of Tactics and Tools for IPM.

Broad Spectrum / Non-Selective

• Controls a wide range of pest organisms– Organophosphates (a.i. malathion)

– Carbamates (a.i. carbaryl, methomyl)

– Pyrethroids (a.i. cyfluthrin, fenpropathrin)y ( y p p )

– Neonicotinoids (a.i. imidacloprid)

Examples of BroadSpectrum

Insecticides

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Narrow Spectrum / Selective

• Controls a narrow range of pest organisms– Insect Growth Regulators (IntrepidTM),

– Bacillus thuringiensis (B.t.), Bt-k (DipelTM) and Bt-t (NovodorTM)

Colorado potato beetleLeptinotarsa decemlineata.

Bt-t toxin is effective againstThis pest of potatoes, tomatoesand other solanaceous crops

Organic Herbicides

• Acetic acid (vinegar-based)• Clove/citric acid based• Herbicidal Soap

– Contact– Non-selective

Do not translocate– Do not translocate– OK for annuals– Perennials- hmmm

• Corn gluten– Pre-emergent– Not effective– Good N fertilizer

Chemical Control

• Although chemical control should be the last tactic considered, it may be the only way to quickly and effectively keep a particular pest in check.

• Used correctly pesticides are indispensable• Used correctly, pesticides are indispensable tools of an IPM program

• Incorrect use of pesticides can lead to:– pest resistance to the pesticide – outbreaks of secondary pests– adverse effects on nontarget organisms – direct hazards to the user

Minimizing the Negative Effects of Chemical Control

• Avoid applying pesticides on a windy day.• Choose narrow over broad spectrum

insecticides.• Spot treat, rather than broadcast a p

pesticide.• Always read the label, follow directions and

do not apply more than is recommended.• Wear protective clothing and eyewear.• Dispose of unwanted pesticides and empty

containers properly.

Summary

• There is no true silver bullet– Pesticides come with pros and cons

– Alternatives to pesticides come with pros and cons

• Conservation biological control is the best, long term pest management strategy available to home gardeners