Preparing for Pests: A Gardener’s Guide

By Hillary Kaufman March 6, 2019 | 8 MIN READ

The Dirt

Spring is around the corner and we’ve got gardening on our minds! And as we all know, with gardens come pests. While pesticides are just one tool in our toolbox to manage pests and weeds, let’s explore how conventional and organic pesticides work and their effects on our local ecosystems.

Sustainable Agriculture

Preparing for Pests: A Gardener’s Guide

Soil and Crop Management

By Hillary Kaufman March 6, 2019 | 8 MIN READ

The Dirt

Spring is around the corner and we’ve got gardening on our minds! And as we all know, with gardens come pests. While pesticides are just one tool in our toolbox to manage pests and weeds, let’s explore how conventional and organic pesticides work and their effects on our local ecosystems.

Spring is coming! So here we are, strategizing about the flowers, veggies, and fruits to fill our gardens. Whether or not we realize it, this practice is something that closely aligns us with our fellow farmers, as we all want the same thing: an abundance of healthy produce grown in an environmentally sustainable way.

This planning reminds us of all the news surrounding pesticides, leaving us with a lot of questions: when should we use pesticides? Which ones are best for our needs – should it be conventional or organic? And what do they actually do to the plants and our surrounding area?

First, consider your garden’s needs to determine which pesticides should be used, if any. We can take a lesson from farmers here by practicing integrated pest management, which some farmers use to reduce pesticide applications. This means closely examining your environmental factors that affect the pest’s ability to thrive, and then creating conditions that they find uninhabitable.

One way to try this is by making sure your soil is full of organic matter; this will reduce pesticide use by keeping plants naturally healthy and strong. You can also regularly check your plants for signs of disease and pests to stay ahead of an infestation.

Should you then decide to apply a pesticide to your garden, consider if you want to go with a conventional or organic product. What’s the difference between them, anyway?

, Preparing for Pests: A Gardener’s Guide

Just like us home gardeners, farmers also carefully consider which pest management products will work best for their crops while keeping their farmland, livestock and local ecosystem safe and healthy.

What Makes a Pesticide Conventional or Organic?

For all pesticides, both conventional and organic, the U.S. Environmental Protection Agency (EPA) oversees its regulation and approval for use in the United States. Organic pesticides require additional approval by the U.S. Department of Agriculture. And for those inquiring, yesorganic pesticides do exist and are commonly used on home gardens and organic commercial crops alike.

As defined by the EPA, conventional pesticides have active ingredients that generally include synthetic chemicals used to prevent, mitigate, destroy, or repel any pest. Most organic pesticides are derived from naturally-occurring substances, although there are several approved synthetic substances for use in organic crop and livestock production. (To view a list of approved organic pesticides, please view this page.)

No matter what type of pesticide you buy, the EPA evaluates all pesticides for potential harm to unintended organisms, including humans, wildlife, plants, and waterways. They also assess the hazards of varying levels of pesticide exposure among humans and domestic animals, from short-term to long-term contact. The EPA uses this information to determine the acceptable amount and frequency of pesticide application that allows the product to effectively work while keeping us safe from overexposure. But if proper precautions are not taken with these products, they can be very harmful to us and our surrounding environment, no matter if it’s conventional or organic. Always follow the directions on the bottle!

Common Pesticides by Type

Large food producers and small home gardeners use both organic and conventional pesticides. Here are some popular pesticides for home use that share active ingredients with commercial ag products. Conventional pesticides include RoundUp Grass & Weed Killer, Daconil Fungicide for plant diseases, and Spectracide for insects. If you’re organically inclined, you may consider pesticides like Natria Grass & Weed Killer, Bonide Copper Fungicide for plant diseases, or Garden Safe Insecticide. These are only a few examples of pesticides, but we’re going to look at these, in particular, to show you what to consider when choosing the right one to manage weeds, plant diseases, and pests on your property. So let’s take a closer look by comparing several of these popular products side-by-side…

Weed Killers: Eradicates targeted grasses and weeds via the direct application of the product., Preparing for Pests: A Gardener’s Guide

Conventional – Glyphosate: RoundUp Grass & Weed Killer has glyphosate and pelargonic acid as the active ingredients. In addition to using it in our own gardens, these products are commonly used in agriculture, golf course management, forestry, and aquatic environments. Glyphosate prevents the plant from manufacturing certain amino acids essential for plant growth and life, thereby destroying the weed.

As we’ve mentioned in our previous post on Roundup, glyphosate is used in over 130 countries on over 100 different types of crops. This is due to its effectiveness in weed control, as well as its low toxicity to us and the surrounding ecosystem, as determined by the U.S. EPA.

As for pelargonic acid, this has also been shown to be low in toxicity. In fact, it’s naturally present in many foods we eat! Though some studies have shown this acid may not make glyphosate products any more effective, at least we know it doesn’t pose a risk to us.

Organic – Herbicidal Soaps: Common organic weed killers, like Natria Grass & Weed Killer, contain herbicidal soaps that eliminate unwanted vegetation. The active ingredient in this product is an ammoniated, or potassium, soap of fatty acids that strip the surface coating on leaf surfaces, causing dehydration to the plants. The fatty acids are commonly extracted from palm, coconut, olive, castor, and cottonseed plants.

Though irritating to the skin and eyes, these herbicidal soaps are very low in toxicity. However, some of these soaps can be toxic to pollinators, so the best time to apply these treatments is at night when pollinators are not active.

Fungicides: Treat plants infected with black spot, rust, blight, powdery mildew, and other diseases.

, Preparing for Pests: A Gardener’s Guide

Conventional – Chlorothalonil: Products like Garden Tech Daconil’s Plant Fungicide contains chlorothalonil, a synthetic chemical that disrupts fungal molecules, thereby killing the fungus. This pesticide has been reviewed to be of very low toxicity, though an irritant to the eyes and throat if inhaled.

Chlorothalonil has been shown to be low in toxicity to pets, birds, and pollinators. However, this chemical is highly toxic to fish and amphibians, so consider this if you live close to the water or a sewer drain.

Organic – Copper Sulfate: Copper sulfate is a commonly used fungicide. The active ingredient in products like Bonide Liquid Copper Fungicide works by denaturing enzymes and other critical proteins in fungal organisms.

Though this pesticide is considered organic, it’s not without controversy.  Not only can this chemical cause severe eye irritation, but more importantly it is quite toxic and can lead to gastrointestinal problems, organ damage, and even shock and death with extreme exposure. Though the EPA hasn’t determined any link between cancer and copper sulfate exposure, several studies from the National Pesticide Information Center show a link in both humans and animals alike. Additionally, this chemical is toxic to birds and aquatic life, so there are many considerations here as it relates to its use, the environment, and run-off. Given its toxicity, it’s vital to follow the product’s directions for use and seriously consider any effects to your surrounding environment.

Insect Killers: Eradicates insects that can damage lawns and plants

, Preparing for Pests: A Gardener’s Guide

Conventional – Gamma-Cyhalothrin: Insecticide products, like Spectracide Triazicide Insect Killer, contain an active compound called Gamma-Cyhalothrin, a broad-spectrum insecticide that acts as a nerve toxin to pests. This chemical is part of the pyrethroid family, the synthetic counterpart of pyrethrin, an organic insecticide. What makes pyrethroids more attractive than their organic counterpart is that the chemical is more stable in sunlight.

Though not shown to be toxic to us when used as directed, both pyrethroids and pyrethrins can be toxic to honeybees, a crucial consideration for our pollinators. This family of chemicals is also toxic to aquatic life. This is another pesticide that you should only spray at night or evening when pollinators are asleep.

Organic – Pyrethrum: In the same chemical family as triazicide is an organic compound derived from a flower that is highly toxic to most insects, but proven non-toxic to humans. A popular product with this compound is Garden Safe Multi-Purpose Garden Insect Killer. When choosing a product like this, it’s important to realize that although it’s effective against pests, it’s also harmful to our pollinators, just like pyrethroids. Also like its conventional counterpart, pyrethrins are toxic to fish and amphibians, so be sure to keep it away from waterways and drains, and be sure to use in the evening and at night.

Another thing to note with this organic compound is to be careful of other active ingredients commonly found in pyrethrin-based products. Some pyrethrin products are combined with piperonyl butoxide (PBO) to make it more potent. However, PBO is not considered “organic”, so be sure that your product of choice doesn’t include this chemical if an organic treatment is important to you.

Toxicity of Common Organic-Approved Pesticides to All Pollinators

, Preparing for Pests: A Gardener’s Guide

Just because it’s organic doesn’t mean it’s safe for the birds and bees. Here’s a chart showing the toxicity of organic pesticides on pollinators. Source for chart:

So, just like farmers do every day, us home gardeners must utilize all the tools in our toolbox to manage pest problems. No matter how you keep pests at bay, be sure to consider not only your plants’ health, but also any animals, waterways, and other environmental sensitivities.

The Bottom Line

Whether for our home garden or a commercial crop, gardeners and farmers must consider their surrounding environment when choosing a pest management system. Should you decide to use a pesticide, be sure to closely follow the product’s directions for best results and minimal impact on you and your local ecosystem – whether it’s conventional or organic.