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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
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