The Truth About Organic Gardening - Jeff Gillman Associate Professor Department of Horticultural Science University of Minnesota
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The Truth About Organic
Gardening
Jeff Gillman
Associate Professor
Department of Horticultural Science
University of Minnesota
Jean-Baptiste Boussingault
The Rise of Nitrogen: Mining Guano
Haber-Bosch Process
Nitrogen from the air + natural gas + high temperature and pressure =
ammonia (NH3)
The Dust Bowl (1930s)
Sir Albert Howard
The Heart of the Organic Garden
www.cambridgema.gov
Jerry Cohen (J.I. Rodale)
www.hort.purdue.edu
Not all organic fertilizer choices are
good….
www.nytimes.com
Rock Phosphate
Ingredients: Corn gluten meal, Bone meal,
Potassium sulfate
Ingredients: Feather meal, bone meal, sulfate
of potash magnesia (Langbeinite), bat guano,
rock phosphate, kelp meal, and gypsumWorm Leachate! Liquid Fertilizer Urine Worm Leachate (example) (1:9 Urine:water) (1:1 Leachate:Water) Nitrogen 600 ppm 700 ppm (urea) 560 ppm (Nitrate) Phosphorus 85 ppm 20 ppm 11 ppm Potassium 332 ppm 100 ppm 2,500 ppm Calcium ? ppm 1.4 ppm 140 ppm Magnesium ? ppm 0.15 ppm 105 ppm
Rachel Carson
What is an Organic Pesticide?
• Occurs naturally
– Botanical
– Inorganics (Many pesticides that are considered
organic are not organic chemically)
• Inhibits the normal growth and / or
development of a pestWhy do We care if a Pesticide is
Organic?
• In the case of a producer, to obtain a premium
for goods
• To avoid contaminating the environment and
ourselves with potentially damaging substances
But do these pesticides offer the human
and environmental safety that we’re
looking for?Not All Organic Pesticides Are Great:
Acute Toxicity
(Lower Numbers mean Higher Toxicity)
Pink = synthetic, Green = organic
• Carbaryl 250-850 mg/kg (oral, rat)
• Pyrethrum 350 - 3,500 mg/kg (oral, rat)
• Permethrin 400 - 4,000 mg/kg (oral, rat)
• Spinosad 3,700 mg/kg (oral, rat)
• Malathion 1,000-10,000 mg/kg (oral, rat)
• Azidirachtin essentially non-toxic
• Fenoxycarb essentially non-toxicChronic Toxicity Pink = synthetic, Green = organic • Malathion - None known • Fenoxycarb - None known • Azidirachtin - Weight reduction at high concentrations, possible reproductive effects • Carbaryl - Slight mutagen, affects lungs, liver and kidneys • Rotenone (no longer available) - Growth retardation, vomiting, liver and kidney irregularities, Parkinsons?
Toxicity to Non-Target Organisms Pink = synthetic, Green = organic • Malathion - Moderately toxic to birds, may be highly toxic to fish (walleye) • Pyrethrum - high aquatic toxicity • Azadirachtin – Negative effects on aquatic life • Copper sulfate – Negative effects on aquatic life, builds up in soils and affects future crops • Carbaryl - Moderately toxic to aquatic life • Fenoxycarb - Toxic to aquatic life
EIQ - Environmental Impact Quotent • Originally put together by Dr. Joe Kovach at Cornell • Tells how badly a particular pesticide may impact humans and the environment
Some EIQ’s • Bt 13.5 • Acephate 17.9 • Spinosad 19.0 • Soap 19.5 • Carbaryl 22.6 • Malathion 23.2 • Sulfur 45.5 • Copper Sulfate 47.8 • Parathion 104.4 • Di-Syston 121.9
How much do we use per year? Would you rather use: • Copper Hydroxide – 3.6 pounds/hectare (EIQ = 33.2) – Field Use EIQ = 46.6 • Sulfur – 60 pounds/hectare (EIQ = 32.7) – Field Use EIQ = 713.7 Or • Maneb - 1.2 pounds/hectare (EIQ = 21.4) – Field Use EIQ = 20.6
Weed Control
If You Must Control Weeds: The
Smartest Organic Choice
• Hand weed!Another Smartest Organic Choice:
Mulch / No-till gardening
Gardentruffles.blogspot.comOther Organic Choices • Corn Gluten Meal – 10-0-0 • Contact Herbicides – Fire – Vinegar – Clove Oil – Garlic Oil – Citric acid • Not Quite Organic – FeHEDTA
Turf Herbicides
Fire – 3 days
Fire – 2 weeks
Vinegar vs. Round up
Round up – 3 days
Household Vinegar – 3 days
Round up – 3 weeks
Household Vinegar – 3 weeks
Round up – 5 weeks
The Big Guns!
Disease Controls: The Smartest
Organic Choices
• Bagging fruit
• Removing diseased
material
• Proper water
and fertility
Don’t Love your plants to death!Other Organic Disease Controls • Milk • Baking soda • Copper sprays • Sulfur
Disease Trials
Chlorothalonil • A Synthetic, Contact Fungicide • Effective on many diseases • “Spray it white, sleep at night”
Chlorothalonil
Aspirin • In the 1970’s a researcher found that injecting aspirin into a tobacco plant would reduce the severity of disease. • Actigard is a chemical similar to aspirin – It has worked reasonably well in our tests.
Aspirin
Cornell Mix • A mix of baking soda, oil, and soap
Cornell Mix
Bordeaux Mix • First used in the Bordeaux region of France. • It is organic, but has some major problems (copper sulfate).
Bordeaux Mix
Sulfur • An ancient fungicide • Is used as a soil amendment to acidify
Sulfur
Milk • Milk is a garden guru remedy • Many researchers have found milk to work at least reasonably well.
Milk
Insect Control: The Smartest
Organic Choices
• Hand squishing
• Water stream
• Encouraging ladybeetles and other beneficials
to visit the garden (have lots of flowers – Not
Doubles!)Other Organic Insect Controls • Bagging fruit • Rotenone • Pyrethrum • Neem / Azidirachen • Spinosad • Bt • Soap • Traps • Reemay
Rotenone • Comes from various plants in the pea family • May be applied as sprays, crystals, or dust • One of the most toxic botanicals to mammals • Very broad spectrum of activity, some activity against mites • Non-toxic to bees
Pyrethrin • Comes from certain chrysanthemums • Provides basic structure for many synthetic pesticides • Very short residual • Highly toxic to aquatic life and beneficials • Nerve toxin - Low chronic toxicity, relatively low acute toxicity, highly toxic to infants
Azadirachtin • Comes from the neem tree • Very low mammalian toxicity • Toxic to fish • Feeding deterrent - kills slowly – not the most effective poison • Allergies exist. Some reproductive problems occur in rats.
Spinosad • Comes from a soil dwelling bacteria • Very effective against thrips, many caterpillars, and Colorado Potato Beetle • Very toxic to bees • Not effective against sucking insects (aphids, mites, etc.)
Bt • Bacteria, Bacillus thuringensis • Effects only target organism – Caterpillars – Some beetles – Some flies • Very little effect on beneficials • Must be eaten to have an effect
Soap • Effective only against soft bodied insects • Kills soft bodied predators • Little effect on non-target organisms
Reemay / Floating Row Covers earthfriendlygardening.worldpress.com Caroline Brown
Traps
www.omafra.gov.on.ca
O. S. Rondon OSUTake Home Message • Know what you are applying • Know why you are applying it • Know what other effects the application will have No Chemicals, Organic or Synthetic, Are All Good or All Bad. It’s Up to Us to Use Them Properly.
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