City of seattle organic pesticides

Organic Pesticides
What works, what doesn’t, and why

Dr. Linda Chalker-Scott
WSU Extension Urban Horticulturist

Seminar recommendations
Based on current, peer-reviewed
science
Include materials certified as OMRI
Include materials registered *only* for
home garden use in Washington state


Modes of action
Preventative*
Feeding
Egg laying
Spore and seed germination

Curative
Suffocation
Starvation
Disruption of biochemical
and/or physiological processes
*must be able to predict

Preventative - feeding
Odor
Essential oils
Neem

Taste
Garlic (lectin)
Neem
Pyrethrin

Touch
Horticultural oils
Kaolin

Preventative –
egg laying & germination
Prevent insect egg laying
Horticultural oils
Kaolin

Prevent fungal spore germination
Bacillus subtilis
Horticultural oils
Kaolin
Potassium bicarbonate
Sulfur

Curative - suffocation
Horticultural oils
Kaolin – fine particle clay
Diatomaceous earth – fine particle silica


Horticultural oils
Includes those made from plants
(seeds, leaves, bark) and
petroleum
Most effective on soft bodied
insects
May suppress disease
Must apply before symptoms
appear
Can be phytotoxic
Can injure beneficials

Curative - starvation
Stomach poison
Bacillus thuringiensis (Bt)
Pyrethrins
Spinosad


Ingestible insecticides
Includes Bt, neem, pyrethrins and spinosad
More targeted to pest species


Curative - disruption
Weed/weed seedling death
Maize gluten meal, vinegar

Insect cuticle abrasion
Diatomaceous earth, kaolin, potassium laurate (soap)

Insect growth and development interference
Neem, nematodes (microscopic worms)

Insect enzyme poisoning
Copper octanoate

Insect neurotoxin
Pyrethrins, spinosad

Pesticide realities
Pesticide registration does not include
product efficacy testing
Success in lab testing does not guarantee
success in the field


Maize gluten meal
High nitrogen byproduct of corn
milling
Registered herbicide
for turf


MGM effectiveness on crab grass control


MGM impact on crab grass root growth


Fungicides
Bacillus subtilus
Canola, corn, jojoba and sesame oils
Copper octanoate
Garlic oil
Kaolin
Potassium bicarbonate
Sulfur


Herbicides
Cinnamon and lemongrass oils
Clove and eucalyptus oils
Herbicidal soap
Limonene
Maize gluten meal
Soybean oil
Vinegar (20% acetic acid)


Insecticides
Bt, nematodes and spinosad
Canola, cottonseed, mineral and sesame oils
Clove and mint oils
Diatomaceous earth and kaolin
Garlic oil
Neem
Nematodes
Potassium laurate
Pyrethrins

Essential oils
Volatile oils (fragrant)
Work best in enclosed areas
Can be phytotoxic


Essential oils for homeowner use
Insects/microbes:
cinnamon, clove, rosemary
and thyme mixture
Insects/microbes: neem oil
Ants: clove oil, mint oil
Roaches: mint oil
Deer: black pepper oil, garlic oil

Popular mixed essential oil
products
“…blending extracts…does not ensure enhanced
biological activity.”
“…numerous plant-derived essential oil
products…have not been subject to rigorous
evaluation.”
“Products vary in their
effectiveness against certain
arthropod pests…and are
phytotoxic.”

Pesticide realities
All registered pesticides are tested to
determine toxic effects on people and on
ecosystems
Home remedies and other unregistered
pesticides can be harmful to people,
pets and the environment


Potential drawbacks –
big and small
Natural does not equal “safe”
Lead arsenate used as a pesticide until 1988
Nicotine and rotenone used as insecticides until
about 8 years ago


big and small
Broad spectrum pesticides can kill
beneficials, other non-target organisms
More frequent application is often
necessary with organic pesticides
Some products phytotoxic


Phytotoxic oils
Species-specific
Too much applied
Temperature too high
Test first!


big and small
Any improperly used
pesticide can
contaminate the
environment
Any improperly used
pesticide can create
resistant pest populations

DDT
resistant
insects
Roundup
resistant
weeds

PICOL database
http://cru66.cahe.wsu.edu/labels/Labels.php


Tips for creating naturally
healthy gardens and landscapes
Purchase disease-resistant plants
Select plants adapted to your site
conditions
Keep plants happy – healthy plants are more
resistant to pests and disease
Increase your plant palette – a more
biodiverse garden is more resistant to pests
and disease
Maintain good garden hygiene by removing
infected plant tissues

Online information


Go back to college with the Garden Professors
http://blogs.extension.org/gardenprofessors/


Bert
Holly
Jeff
Linda


Visit us on Facebook!

www.facebook.com/TheGardenProfessors


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https://www.facebook.com/groups/20037544148


New WSU website for garden info
http://gardening.wsu.edu/


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