Prepared by Dr. Mike Klahr, Boone County Horticulture Extension Agent
Edited by Dr. Tim Coolong, UK Extension Vegetable Specialist
Organic Pesticides
• Variety of organic
pesticides.
– Oils
– Soaps
– Derived from plants
– Natural occurring
pathogens.
• READ THE LABEL!
• Follow all label instructions.
Trade names are used as examples. No endorsement is intended, nor criticism implied
of similar products not mentioned. Always read and follow the product label.
Insecticidal Soap
• Generally considered to
be among the least toxic
pesticides available.
• Used to control softbodied pests such as
aphids and mealybugs.
• Must have direct contact.
Aphid
Mealybug
Insecticidal Soap
• Non toxic to beneficial
insects such as parasitic
wasps and ladybugs.
• No residual effect.
• Once the spray has
dried, walking over the
soap residue will not
harm a moving insect.
Aphid
Mealybug
Insecticidal Soap
• Some plants are
sensitive to soaps.
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Japanese Maple
Lantana
Bleeding Heart
Ferns
Palms
• If unsure about plant
sensitivity, spray on a
small test section.
Horticultural Oil: Dormant Oil
• Refined petroleum products.
• Used to control pests,
such as scale, mites, etc.
• Interferes with the pest's
respiration and membrane
function.
• For oil to be effective, it
must come in direct
contact with the pest or
egg; therefore, thorough
coverage is essential for
proper control.
Cottony Maple Scale
Euonymus Scale
Obscure Scale
Horticultural Oil: Dormant Oil
• Do not use when
temperatures are below 40°F
or above 100°F.
• Don’t spray when humidity
will be over 90% for 36
hours; slows drying which
may burn plants.
• May damage plants when
flowering buds are forming
and shoot elongation is
occurring.
• Consult label for list of oil
sensitive plants.
– Maple, hickory, black walnut
Cottony Maple Scale
Euonymus Scale
Obscure Scale
Horticultural Oil: Summer Oil
• Highly refined petroleum oil
(mineral oils).
• May be used during growing
season.
• Avoid oil sensitive plants.
• Oils will also kill predatory
mites.
• Oils are toxic to fish.
Pine Needle Scale
Bt-Bacillus Thuringiensis• Naturally occurring bacteria.
• Different strains of Bt.
• Bt israelensis: mosquito and
fungus gnat larva. (MosquitoDunks)
• Bt kurstaki: Leaf-eating
caterpillars.
• Does not control sawfly larva.
– Not a true caterpillar.
Bt-Bacillus Thuringiensis
• Apply when larva are small.
• Most be eaten.
• Will kill “pest” caterpillars and
“desirable” caterpillars.
• Do not use in or near a
Butterfly Garden!
Parsleyworm a.k.a.
Black Swallowtail larva
Pyrethrin (Pyrethrum)
• Mixture of compounds extracted
from the flower of pyrethrum daisy
(Chrysanthemum coccineum and C.
marshalli)
• Primarily grown in Kenya.
• Used on many plants including
fruits and vegetables.
• Broad target insecticide also kills
mites and spiders.
• Quickly paralyze insects.
Pyrethrins
• Attacks the nervous system.
• Very effective contact spray.
• Target must be hit directly and spray
may need to be repeated.
• Broken down quickly by sunlight,
moisture, and air.
• No residue is left behind.
• Toxic to fish and tadpoles.
• Toxic to beneficial insect such as
honeybees.
• Pyrethroid = Synthetic (Man made)
Slug Traps
• Beer Traps
– Alcoholic or nonalcoholic
– Fill saucer and sink saucer to
ground level
– Slugs are attracted to smell, fall
in and drown.
– Check and replace often.
– Dogs may drink the beer.
• Cardboard or wooden board.
– Slugs hide during the day.
– Check board daily.
– Drown slugs in soapy water.
Beneficial Insects: Ladybugs
• Many species of ladybugs
– Native and non native.
• Ladybugs can feed on as many as 5,000 aphids in its
lifetime.
• Adult and larva both feed on aphids.
Beneficial Insects: Lacewings
• Eggs may be laid singly or small groups; usually close to a
food source.
• Eggs resemble a q-tip.
• Larvae are also known as “Aphid Lions”
• Adults are weak fliers and feed mostly on nectar and
pollen.
• More expensive than ladybugs.
Beneficial Insects: Braconid Wasps
• Many species of braconid
wasps.
• Species Costesia congregatus
attacks tomato hornworm
and tobacco hornworm.
• Female lays eggs just under
the skin.
• Larva feed on host from
inside and tunnel out.
• Once outside, they build
cocoons on host.
Beneficial Insects: Braconid Wasps
• When adults emerge, host
soon dies.
• Adults are small; about 1/8”.
• If you find a hornworm
covered in cocoons, leave it.
• It will soon die.
• It is now the host to a new
generation of wasps.
Prepared by Dr. Mike Klahr, Boone County Horticulture Extension Agent
Edited by Dr. Tim Coolong, UK Extension Vegetable Specialist