Is Pyrethrum a Safe Organic Pesticide?

Pyrethrum has attracted attention as an organic pesticide. It packs a punch against many common pests, but is it truly safe for use in your home and gardens? Keep reading to learn the ins and outs of pyrethrum and find answers to your safety-related questions.

What is Pyrethrum?

Pyrethrum is a naturally-derived insecticide from the Pyrethrum daisy (Chrysanthemum cinerariifolium,) sometimes called the Dalmatian chrysanthemum. This perennial flower is loaded with chemicals called pyrethrins that are toxic to a wide variety of insects, from flies to moths.

Since pyrethrum is directly extracted from plants, and since it’s considered relatively non-toxic to humans, it’s now approved in the U.S. for use on certified organic farms.

Pyrethrum works similar to pyrethroids such as permethrin, but it is not a pyrethroid itself. These synthetic cousins are far more potent and aren’t approved for organic gardening in the same way as pyrethrum.

How Pyrethrum Works

Pyrethrum’s potency lies in its ability to swiftly affect an insect’s nervous system. This quick action results in paralysis and, eventually, death. 

As an insecticide with broad-spectrum capabilities, pyrethrum can paralyze flying insects almost immediately upon contact. However, a dose that’s too low may allow for the pest to recover, so it’s crucial to apply pyrethrum carefully and in just the right amount.

Many sprays that contain pyrethrum also have additional chemicals called synergists, which serve to improve their efficacy. Piperonyl butoxide, or PBO, is a common addition that’s both toxic and non-organic. It’s rare to find pure pyrethrum in most stores, but if you’re an organic gardener that wants to avoid synthetic chemicals, you might have to find a specialty supplier that sells it.

Pyrethrum Safety and Environmental Impact

Pyrethrum has a reputation as one of the least toxic pesticides for humans and pets. However, it’s not entirely free from risks. If you have sensitive skin or respiratory issues, you may experience irritation or allergic reactions upon exposure to it.

Pyrethrum can also affect the broader environment in these ways:

• Risk to aquatic life: Pyrethrum is a toxic chemical for fish and other aquatic organisms. You’ll need to apply it so it won’t run off into waterways.
• Harm to beneficial insects: Pyrethrum is an indiscriminate killer that harms both pests and beneficial insects like pollinators and predators. If enough predators die out, the risk of a pest resurgence increases.
• Rapid breakdown: On the upside, pyrethrins degrade quickly in sunlight, often within days. That curbs long-term environmental disruption for soil and produce.

Using Pyrethrum Safely

Pyrethrum-based pesticides can be a useful tool when you apply them properly. Follow these instructions and tips, along with any instructions on the bottle, for best results and low impact.

• Find an OMRI-certified product: OMRI-certified pyrethrum sprays have no toxic synthetic chemicals added.
• Mix your own spray: You can mix your own pyrethrum spray with dried pyrethrum daisy flowers, water, and a bit of dish soap.
• Stay away from synthetics: If you’re an organic gardener, don’t buy synthetic products labeled permethrin, cypermethrin, deltamethrin, or tetramethrin. None of those ingredients are approved for organic gardening.
• Spot-treat only: Limit pyrethrum use to heavily-infested areas. If you apply it as a blanket layer, it could kill off beneficial insects that you want to keep alive.
• Time it right: Apply pyrethrum in the evenings when beneficial insects are less active.

Lastly, you shouldn’t depend on pyrethrum as your sole pest control strategy. It performs best when you integrate it with other approaches. For example, if you cultivate Dalmatian chrysanthemums alongside other plants, that might deter insects without any extra chemical intervention. You can also build an environment that attracts beneficial insects that helps them thrive.

If you’re not sure whether you should use pyrethrum in your yard—or if you don’t have the time to treat your yard, let alone research the subject—it’s a good idea to consult with a lawn care or pest control company about your situation.