How Safe are Organic Garden Chemicals?

America’s Favorite Retired College Horticulture Professor, Debbie Flower, discusses garden chemical safety, including: when organic controls can be hazardous; the dangers of homemade pesticides; how to check for organic ingredients in a pesticide product; and, ways to determine if your organic garden “inputs” (water, mulches, manures) are safe to use.

Despite your best organic efforts, this CDC study says there’s a high chance that glyphosate is probably in your urine:

Here’s the background on one statement in that podcast: that there might be glyphosate in your urine:

“…more than 80 percent of urine samples drawn from children and adults participating in a US health study contained a weedkilling chemical linked to cancer and other health problems. The June 30 report by a unit of the Centers for Disease Control and Prevention (CDC) found that out of 2,310 urine samples collected, 1,885 were laced with detectable traces of glyphosate, the active ingredient in herbicides sold around the world, including the widely used Roundup brand.”

Sources For Water Testing:

National Testing Laboratories: https://watercheck.com

Water Testing Accredited Laboratories in California: https://www.calwater.com/waterquality/water-quality-testing-labs/

Source for Organic rice straw: Brokenbox Ranch, Williams, CA

From Clemson University: “Less Toxic Insecticides”:

Factsheet | HGIC 2770 | Updated: Aug 27, 2021 |

While a good pest management plan will start with preventative, cultural, and other non-chemical methods, these are sometimes not completely effective on their own. In this case, a pesticide may be considered. If pesticide use is deemed necessary for control of the pest problem, it is good practice to use the least toxic pesticide that will do the job effectively. Although all pesticides are by their nature toxic in some way to some organisms, there are now a number of “less toxic” pesticide options.

Insecticides may be considered less toxic for several reasons. Generally, they should pose less risk to human and environmental health than conventional insecticides. Many break down rapidly and do not accumulate in the body or environment. Some are very pest specific and do little or no damage to other organisms. Still, others, such as bait stations, minimize human exposure to the pesticide.

While “organic” insecticides are often less damaging to the environment than conventional insecticides, they are still pesticides. All pesticides should be evaluated before selection for level of toxicity, effectiveness, environmental impacts, and costs. Some “organic” or natural pesticides are as toxic, or even more toxic, than some synthetic pesticides. All pesticide products have a toxicity signal word on the label, which will be “caution”, “warning”, or “danger”. Choose the products with “caution” on the label, as they are least apt to harm the user and the environment.

Soaps & Oils

Insecticidal soaps and oils have a number of advantages for controlling insects. They are virtually non-toxic to humans and other mammals and are relatively safe to beneficial insects in the landscape. They control a wide range of common soft-bodied pests, including aphids, mealybugs, thrips, whiteflies, mites, and scales. It is difficult for pests to develop resistance to oils and soaps. Soaps and oils are now readily available and relatively inexpensive.

Both soaps and oils can cause damage to plants if applied when plants are water-stressed, temperatures are above 90 °F, sprayed in direct sunlight, or when high humidity prevents rapid drying. Some plants are sensitive to oil or insecticidal soap sprays. See sensitive plant lists in HGIC 2771, Insecticidal Soaps for Garden Pest Control. Read and follow the label.

Since soaps and oils work on contact, an effective application must coat both the upper and lower leaf surfaces as well as stems for best results. Repeated applications may be necessary. Apply soap or oil sprays in the early morning or late evening to reduce drying times for more effective insect pest control.

Insecticidal Soaps: Insecticidal soaps kill by suffocation; additionally, they damage the protective coat of soft-bodied insects, causing them to dehydrate.

Homemade soap recipes are not recommended because they may be more likely to cause foliage burn. Commercial insecticidal soaps are tested on plants and are less likely to cause damage. Some are available as concentrates to dilute before spraying, and some are available as pre-mixed Ready to Use (RTU) bottles. Examples of insecticidal soap products are:

* Bonide Insecticidal Soap RTU

* Espoma Organic Insect Soap RTU

* Garden Safe Insecticidal Soap Insect Killer RTU

* Miracle-Gro Natures’s Care Insecticidal Soap RTU

* Natria Insecticidal Soap RTU

* Natural Guard Insecticidal Soap Concentrate

* Safer Brand Insect Killing Soap Concentrate

* Whitney Farms Insecticidal Soap RTU

Horticultural Oils: Oil products smother soft-bodied insects on contact. Oils are formulated as either horticultural or dormant oils. Dormant oils are heavier, less refined oils used on dormant, leafless plants to control overwintering insects (e.g., aphids, spider mites, and scales). Dormant oils will damage plant foliage if used during the growing season. Horticultural oils are also called summer or superior oils, and these are lighter and more refined. They can be applied to both actively growing plants as well as dormant plants for insect pest control. Do not apply horticultural oil sprays when the temperature is above 90 °F, below 45 °F, or if rain is in the forecast within 24 hours.

Most horticultural oils are applied at a 1 to 2% mix with water to spray actively growing plants (this would be 2½ to 5 tablespoons of oil with a gallon of water). To use horticultural oil as a “dormant oil” spray to control pests on woody plant bark, they are mixed at 4% with water (this would be 10 tablespoons of oil per gallon of water). Always spray very late in the day to slow drying time and to get better insect control. Most are available as concentrates made to dilute with water in a sprayer, although some are available as either a Ready to Spray (RTS), which is a bottle to attach to a garden hose for spraying, or as a Ready to Use (RTU), which is a pre-mixed spray bottle. Examples of horticultural oils are:

* Bonide All Seasons Spray Oil Concentrate; & RTS; & RTU

* Ferti-lome Horticultural Oil Spray Concentrate; & RTS

* Monterey Horticultural Oil Concentrate; & RTS; & RTU

* Safer Brand Horticultural & Dormant Spray Oil Concentrate

* Southern Ag Parafine Horticultural Oil (concentrate)

* Summit Year Round Spray Oil Concentrate

Sesame Oil: Sesame oil sprays work in the same manner as horticultural oils. Follow label directions for mixing and use.

* Organocide Bee Safe 3-in-1 Garden Spray Concentrate; RTS; & RTU

Botanical Insecticides

Botanical insecticides are naturally occurring toxins extracted from plants. There are several advantages to using botanical rather than synthetic insecticides. Plant derived insecticides break down quickly in the environment, resulting in little risk of residues on food crops and less risk to beneficial insects. Some materials can be used shortly before harvest. Most botanicals are rapid acting, and most, but not all botanicals are of low to moderate toxicity to mammals. Most botanical insecticides must be eaten by the insect pest. Therefore, they are primarily harmful to these pests and do little harm to beneficial insects.

There can also be disadvantages to using these products. Rapid breakdown, while less risky to health and environment, often creates a need for precise timing or more frequent applications. Several botanical insecticides are quite toxic and should be handled accordingly. Some botanical insecticides can be difficult to find in local stores.

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