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Are Organic Fertilizers Harmful to Pollinators?

Question:

Is organic fertilizer harmful to pollinators, especially my fave, bumble bees?  My husband bought this stuff and I don’t know if it is harmful to bees, or not.  I want to help save our precious pollinators.

Answer:

Thank you for keeping bumble bees in mind in your vegetable garden.  Note that tomato plants are self-fertile, but their pollination will be far more successful with the assistance of bumble bees – resulting in more fruit for you to enjoy.  Bumble bees are incredibly effective pollinators of tomato plants, vibrating their bodies as they move from flower to flower, releasing a substantial amount of pollen as they go. This behavior is known as “buzz pollination” and is important not only for tomatoes, but for some other edible plants that you might grow, like blueberries.

With regard to the impact of organic fertilizers on bumble bees, I am not aware of any research on the toxicity to bees from the extra nitrogen, phosphorus or potassium (NPK) delivered by fertilizers to a plant.  Typically it’s the pesticides that we worry about.  But, there is much that we don’t know about the interactions between plants and insects. 

I think one unanswered question is –  can excessive fertilization impact the nutrition of the pollen and/or nectar that a treated plant produces?  We know that rising CO2 levels can impact plant physiology and reduce the amount of protein in pollen that bees need.  The Yale School of Forestry & Environmental Studies published an interesting article on this subject in YaleEnvironment360

https://e360.yale.edu/features/bee_collapse_co2_climate_change_agriculture

As mentioned, there is much that we still don’t know about plant and animal interactions.  If you decide to use a fertilizer for crops like tomatoes, use an organic, slow release product that is OMRI certified (Organic Materials Review Institute), rather than a chemical fertilizer. “OMRI” will be specified on the product label.  As an alternative, consider using organic compost which will also help to increase soil health.

Best of luck, and thanks for caring about our challenged bees!  For more information on bees, take a look at these EcoBeneficial interviews with John Hayden from The Farm Between on helping native bees: 

Going Pesticide-Free for Pollinators

https://www.ecobeneficial.com/videos/going-pesticide-free-pollinators/

Bee Houses and Bumblekultur

https://www.ecobeneficial.com/videos/bee-houses-and-bumblekultur-with-john-hayden/

Happy planting from Kim Eierman at EcoBeneficial!