Lower Risk Pest Control Products & Practices

Lower Risk Pest Control Products &

PracticesDr. Heidi Kratsch

Horticulture Specialist2015 Master Gardener Training

Know the range of lower risk products available for controlling insect pests.

Understand when and how to use lower risk products.

Be able to select the best type of product, considering the pest, time of year and plant species affected.

Describe lower risk pest control practices that could be used to decrease chemical pesticide use.

Learning Objectives

A pest is a living organism that is a nuisance, or causes damage or serious injury to plants or animals.

Examples of pests:◦ Weeds◦ Insects◦ Mites◦ Rodents◦ Bacteria◦ Fungi

What is a pest?

Proper: Pruning Fertilizing Watering Selecting pest-

resistant species/ cultivars.

Cultural controls

Shrub roses are hardy to our climate and often disease-resistant.

Mulch Soil solarization Hoeing weeds Spraying leaves

forcefully with water to remove insects

Hand-picking/squishing

Traps Exclusion barriers

Physical/mechanical controls

Purchasing beneficial organisms such as insects that eat or parasitize other insects

Protecting existing beneficial predators

Biological controls

Oils and soaps Botanical

pesticides Microbial

pesticides

Lower risk chemical pesticides

Replant In extreme cases, where a plant requires regular pesticide treatment, consider replanting with a more pest-resistant species.

When all else fails…

Controlling insects

Apply at the proper time Treat pest at its

most vulnerable developmental stage.

For insects, just before or just after egg hatch is a vulnerable stage.

www.bugwood.org

More selective Lower toxicity Shorter residuals Some are easier on

natural enemies

Lower risk insecticides

It is a mistake to assume that naturally occurring chemicals are non-toxic.

Many organically derived products that kill harmful insects will also kill beneficial insects.

Low Risk does not mean no risk

Avoid spraying any insecticide when beneficial insects and pollinators are actively feeding on plants.

http://www.xerces.org/wp-content/uploads/2009/12/xerces-organic-approved-pesticides-factsheet.pdf

Most effective for wingless insects.

Increased humidity creates an unfavorable environment for some pests.

Strong spray of water

Aphids (wingless varieties)

Mealybugs Mites (arachnids) Thrips

Insects most affected:

Spray away from other plants to prevent re-infestation. Spraying towards a wall or driveway works well to “cook” pests before they can crawl back.

Must get undersides of leaves and within leaf axils for good control.

Best for sturdy plants

Trapping – coddling moth

Used for monitoring adult activity

Trapping earwigs

Used to knock back the population

Place wooden boards throughout the garden

Check under them every morning

Destroy squash bugs or vacuum them up

Trapping squash bugs

Sticky barriers

Used for trapping or monitoring

Best for airborne pests

Yellow for whiteflies, fungus gnats, thrips, winged aphids, leafminers scales

Blue for selectively monitoring thrips

Sticky cards

Floating row covers Available in 0.3 to

1.25 oz/sq yd Lighter weight covers

good for insect exclusion

Must seal bottom edges

Heavier weight covers good for cold protection This row cover is not

completely sealed and will allow insects to crawl in.

Row cover supported with hoops

Prevent adults from laying eggs

Caution: row covers interrupt natural insect movement (natural enemies, pollinators, etc.)

Weeds also an issue

Low tunnels

Don’t forget to seal the edges!

These overwinter outside the garden: Aphids Cabbage worm Cabbage looper Leafhoppers Leafminers Squash bug Cucumber beetle Bean beetle Corn earworm Grasshopper Whitefly

Know how insects overwinter

Your job is to keep them out during the growing season.

Squash bug

These overwinter near last year's plant host:             Tomato hornworm Onion and seedcorn

maggot Corn rootworm Colorado potato beetle Flea beetle (this pest

affects many vegetable seedlings)

Know how insects overwinter

Tomato hornworm in the pupal stage

Best strategy is to rotate vegetable hosts of these pests.

These overwinter in scattered locations over the garden: Slugs Cutworms Millipedes Sowbugs

Know how insects overwinter

Inspect plants frequently and remove row cover when found, to allow access to natural enemies.

Cutworm damage on potato

Lower risk insecticides

Causes insects to dry out by absorbing the oils and fats from the cuticle of the exoskeleton.

Sharp edges are abrasive to insects.

Look for the insect control formula.

Diatomaceous earth (DE)

Made from the fossilized remains of tiny, aquatic organisms called diatoms.

Their skeletons are made of a natural substance called silica.

What is diatomaceous earth?

You must wear a dust mask when applying DE.

Effective on many insects: Ants Aphids Earwigs Flea beetles Slugs Mites (arachnids) Squash bugsAnd the larvae of many insects.

Insects most affected:

Effect of diatomaceous earth on a centipede.

How to use DE

Dormant –type oils Used on woody plants before budbreak.

Summer-type oils Used on plants when leaves are present.

Work by smothering insects or their eggs.

Horticultural (mineral) oils

Spiracles (breathing pores)

Choice depends on life history of the pest

Adelgids Aphids Mites (arachnids) Scale Leafhoppers Whiteflies

Also- powdery mildew (not an insect!)

Insects most affected

Black walnut Cryptomeria Douglas-fir Hickory Juniper and cedar Maples Redbud Smoketree Spruce

Plants sensitive to horticultural oils

Horticultural oils can cause a temporary loss of blue color on blue spruce needles.

Know the life history of a pest and choose the correct seasonal oil.

Follow label directions. Use the lowest possible concentration (1-2% in

summer; 3-4% in winter). Keep the mixture agitated at all times to prevent

separation. Apply summer oils to plants with fully hydrated, but

dry-surfaced leaves. Only apply oils when target pests are present. Be sure to cover the target insect completely; the oil

will only work if the insect is completely enveloped.

How to use horticultural oils

Extracted from the Neem tree

Most formulations contain azadirachtin.

Controls over 200 types of insects, mites, and nematodes.

Should not be exposed to sunlight.

Neem oil

Neem tree grows in arid tropical environments. Neem oil is less toxic to mammals and birds than other insecticides.

Aphids Colorado potato

beetle Leaf-eating

caterpillars Mealybugs Mexican bean

beetle Squash bugs

Insects most affected:

Neem works as an Insect Growth Regulator

Neem oil causes many insects to feed less, grow more slowly, molt less, and lose interest in laying eggs. 

Best used preventively, or on young insects

Shake well before using.

How to use neem oil

Neem is a contact insecticide and must cover insects to be effective.

Most effective on small, soft-bodied insects.

Remove protective cuticle on insect body.

Insecticidal soaps

Spray plants thoroughly, including undersides of leaves where insects hide out.

Aphids Mealybugs Psyllids Thrips Scale crawlers

(emerge just after egg-hatch)

Spider mites

Insects most affected:

Dilute to 2 to 3 percent (read the label!)

Do not apply in full sun or mid day heat.

Wash plants a couple hours after application.

Re-apply every 4-7 days.

How to use insecticidal soaps

Metal ions in hard water can cause soaps to form a precipitate on leaves.

Plants under drought stress

Young transplants Unrooted cuttings

and plants with soft young growth

They are more likely to develop phytotoxic symptoms and should not be treated with soap.

Do not apply soaps to:

Insecticidal soaps sold for control of insects: are selected to

control insects; are selected to

minimize potential plant injury; and

are of consistent manufacture.

Do not recommend dish soaps!

Pansy leaves burned by dishwashing liquid

= Naturally occurring chemicals extracted from plants. Examples: Pyrethrins – broad

spectrum Rotenone -effective

on leaf-eating caterpillars and beetles.

Botanical insecticides

Pyrethrins are extracted from the Pyrethrum daisy and used to control many insect pests.

Pyrethrins are neurotoxins derived from the pyrethrum daisy that attack the nervous systems of insects.

Pyrethroids are synthetic materials designed to imitate natural pyrethrum.

Pyrethrins vs. Pyrethroids

Often combined with soaps or oils

Must come into contact with the pest

One of the oldest pesticides known

Strongest insecticide allowed under National Organic Standards guidelines

Pyrethrins

Piperonyl butoxide (PBO) sometimes added to increase insect mortality. This is NOT considered organic.

Aphids Armyworm Colorado potato beetle Cucumber beetle Cutworms Fungus gnats Leafhoppers Squash bugs Thrips Whiteflies

Highly toxic to beneficials!

Insects most affected by pyrethrins

Read the label!!

1. Insect eats Bt crystals and spores.

2. Toxin binds to receptors in the gut.

3. Causes gut wall to break down and interferes with digestion.

4. Insect stops feeding and dies.

Microbial insecticide Bt

How Bt works…

Bt = Bacillus thuringiensis

Bt var. kurstaki controls many caterpillars.

Bt var. israelensis controls black flies,

fungus gnats and certain types of mosquitoes.

Does not stay active in the environment for long (has a low residual).

Microbial insecticides are selective

Most microbial insecticides are toxic to a single species or group of insects, so you can often target a pest without the risk of killing beneficial insects in the process.

Natural predators

Ladybird beetle

They feed on aphids, scale crawlers, mealybugs, and mites.

Adult

Larva

Green lacewingAdult

Larva

Eggs

Larvae feed on aphids, mealybugs, whiteflies, small caterpillars, butterfly eggs, small beetles, scale crawlers, leafhoppers, thrips, and other small insects and eggs. They also eat mites, and they sometimes eat each other.www.manageNVpests.info

Ground beetleAdult

Larva

Shapes and colors vary – shiny.

Ground dwellers Adults and larvae

are predators. They feed on

armyworms, cutworms, snails, slugs, root-feeding insects, larvae and pupae.

Syrphid (hover) fly

Adults feed on nectar. Larvae feed on aphids, scale insects and thrips.

AdultLarva

Big-eyed bug

They feed on small caterpillars, mites, thrips, whiteflies, aphids, and other soft-bodied insects. They also suck plant juices but do little harm to plants.

AdultNymph

Managing weeds

Abundance of weeds is symptomatic of environmental conditions.

A single control technique is rarely sufficient.

Prevention is the most effective action!

IPM for weeds

Destroy weeds before planting Good seed-bed preparation Seed properly Planting species that can outcompete

weeds Avoid over- or under-fertilizing Avoid over- or under-watering

Good cultural practices

It’s easier to control the first weed than acres of weeds – walk your property often!

Practical tips in weed management

It’s easier to pull a seedling than a mature weed – small is beautiful!

Practical tips in weed management

Coyote tobacco

Never let an annual or biennial weed produce seeds.

Practical tips in weed management

Musk thistle seeds

It’s easier pull weeds when the soil is moist.

Practical tips in weed management

Deep tilling brings weed seeds to the surface and harms soil structure.

Practical tips in weed management

Works best for: Small infestations Young weeds Annuals and

biennials Shallow-rooted

species Ineffective for

rhizomatous species Wear gloves!

Good candidates: Cheatgrass Common mullein Dalmation toadflax Flixweed Kochia Medusahead Oxeye daisy Puncturevine Thistles (except

Canada thistle)

Hand-pulling

Works best for: Large, flat, dry areas Preventing tall

biennial species from setting seed

Preventing tumbling action

Weakens weeds. Cut weeds may

vigorously resprout.

Limitations: Rarely kills weeds Repeated mowing

needed Stimulates some

weeds (tamarisk, Russian olive)

Not as effective on strongly rhizomatous weeds (Russian knapweed)

Mowing and cutting

Soil solarization

Solarizing a raised bed prior to planting

Works best for: Many grass seeds Bindweed Buttercup Chickweed Lambsquarters Miner’s lettuce Mallow Pigweed Shephards’ purse Sowthistle

Steps: Cultivate, then

smooth the soil Irrigate thoroughly Roll out plastic tarp

(1/5 to 2 mils thick) Bury the edges Leave on for 4-6

weeks during the hottest time of the year.

Soil solarization

Allowed in organic practice

Provides N (10% N by weight)

Preemergent weed control

Expensive! Apply just as forsythia

begins bloom 10 lbs. per 1,000 sq.

ft.

Corn gluten meal

Corn gluten meal can be applied in a granular or liquid form.

Questions?