Planting Garden Center Flowers Is Good For Bees And Other Beneficial Insects

beephoto4webEditor’s Note: Michigan State University Extension recently published this consumer article by Dr. David Smitley on why the discovery of neonicotinoid insecticides in leaves and flowers of some garden center plants should not stop consumers from buying and planting flowers, because the benefit to bees far outweighs the potential risk. It’s a good resource to share with your customers and consumers. Dr. Smitley’s work is funded in part by MSU’s AgBioResearch.

Recently, some Internet and media sources have suggested that buying and planting flowers from your local garden center could be harmful to bees because traces of neonicotinoid insecticides were found in the leaves and flowers of plants randomly purchased from garden centers around the country. Although it is true that concentrations of more than 100 ppb of imidacloprid in nectar or pollen are toxic to honey bees, and lower concentrations (10 to 100 ppb) could affect their foraging behavior and immune response, the potential harm to pollinators in the yard and garden from buying and purchasing flowers from a garden center has been exaggerated. In fact, planting annual and perennial flowers and flowering trees and shrubs is expected to be beneficial for bees and other beneficial insects.

Greenhouse and nursery growers started using alternatives to neonicotinoid insecticides this year, and the amount used is less than in previous years. Michigan State University began working with growers in March of 2014 to identify pest control strategies where neonicotinoids have been used so that alternative strategies could be adopted. Also, experiments were initiated to determine the risk to bees after treated plants are sold and planted in the yard and garden. Several experiments are in progress now, where treated plants are put into screened cages with colonies of bumble bees.

People should not become too alarmed by the detection of neonicotinoids found in the leaves and flowers of some garden center plants. This does not mean that the plants will be toxic to bees. Here are several reasons why:

  • Michigan is home to some of the largest greenhouse flower growers in the country. In a recent survey we found most growers do not make soil applications of neonicotinoid applications to petunias, impatiens, marigolds, New Guinea impatiens, verbena, ageratum, celosia, dianthus, portulaca, salvia, snapdragons, vinca and other bedding plants grown in flats. They usually do not spray flowers with any insecticide in the last two weeks of production. So flowers sold by the flat should be safe for bees.
  • Many trees and shrubs, including all conifers, and many broadleaf trees like maple and oak are wind pollinated and are not usually visited by bees.
  • Perennial flowers, roses, flowering shrubs and flowering trees will be a valuable resource for bees and other pollinators for many years after they are planted, while the risk to bees will be limited to those plants that were treated with a soil drench, and only when they are flowering in the first year.
  • Bees feed on a large variety of flowering plants, and often forage as far away as a mile from their colony. Because they are feeding on many different plants, the presence of a neonicotinoid insecticide in one plant will be diluted when they feed on untreated plants.

Flowers bought in flats should be completely safe to bees. If you are worried about some of the perennials or flowering trees and shrubs that you purchase, the flowers could be removed during the first summer after planting. Also, if you buy trees or shrubs in a container, you can reduce the amount of imidacloprid or any neonicotinoid insecticide that may be present in the soil by watering them until you see water emerging from the bottom of the container, and then continue to run the water for another 10 minutes. This will flush any neonicotinoid insecticide residue that is not tightly bound to the organic matter in the soil.

Another way to encourage bees and beneficial insects is to avoid spraying insecticides in the yard and garden as much as possible, and never spray flower blossoms. If you have a problem with caterpillars chewing too many holes in the leaves of some plants, you can use a product containing Bacillus thuringensis or Bt, without harming bees and other beneficial insects.

Another bee-friendly option is to use horticultural oil or an insecticidal soap. They are effective on most soft-bodied insects and can be used on cool mornings, less than 50 degrees Fahrenheit, after sunset, or at any time that bees are not present. The soap and oil residue is not harmful to bees, but spraying them directly is. Soap and oil can cause some plant injury, especially to open flowers, so do not exceed the rate given on the product label. In rare cases where a plant needs to be protected against damaging insects by using a broad-spectrum insecticide, it should be sprayed after petal-fall (after the plant is done blooming).

honey bee2

What about neonicotinoid insecticides?

As with all insecticides, do not spray neonicotinoids on flower blossoms. Also, because they are systemic when absorbed by the roots, avoid using products that contain imidacloprid or clothianidin as a soil drench around plants that are attractive to bees. Using them as a basal (soil) drench around the base of wind-pollinated trees and shrubs, like most evergreens and trees like oaks and ash, is not likely to harm bees because bees rarely visit wind-pollinated plants.

What about the pesticides used on flowers, trees and shrubs sold at garden centers?

Nursery growers and greenhouse growers have been working closely with Michigan State University on how to grow plants that are safe for bees and other pollinators. They are following best management practices that include using alternatives to neonicotinoid insecticides, and they avoid spraying flowers close to when they are shipped to garden centers, to make plants as safe for pollinators as possible.

Could pesticide residue in the soil of garden center plants be contributing to the decline of commercial honey bee colonies?

Although it is desirable to grow flowers in the yard and garden for bees and other beneficial insects, our garden plants are not usually a primary food source for commercial honey bee colonies, and therefore have very little to do with the problems that beekeepers have had.

For more information on identifying and encouraging pollinators, see the Michigan State University Extension bulletin, “Native Bees & Their Conservation on Farmland,” by Rufus Isaacs and Julianna Tuell.

Source: Michigan State University Extension.

Topics: ,

Leave a Reply

Latest Stories
cuttings-facility

December 13, 2017

New Webinars Address Effective Propagation Techniques

e-Gro, an online clearing house for alerts about greenhouse disease, insect, environmental, physiological, and nutritional disorders, recently posted two new propagation-related webinars on YouTube.

Read More
Oasis-Transportation-Solutions

December 12, 2017

New Products Designed to Protect the Quality of Plants …

The innovative technologies from Oasis Grower Solutions are aimed at ensuring that the supply chain delivers the best possible consumer plant experience.

Read More

December 12, 2017

Research Sheds Light on How to Manage Plant Stress With…

An innovative system developed by Chinese researchers uses rapid imagery to indicate plant health, enabling growers to respond quickly and automatically to plant stress.

Read More
Combo-at-Youngs-Plant-Farm

December 12, 2017

How to Produce Stunning Combination Containers

It’s easy to produce your own attention-grabbing combos, if you follow this advice from a master combination designer.

Read More
ISO-Group-Transplanter-feature

December 11, 2017

Evaluating Robotic Transplanters for Plant Cuttings

There are several factors that might affect your decision to invest in transplant robots, based on initial observations and reported information about available equipment.

Read More
Overhead-irrigation-to-maintain-moisture-content-feature

December 10, 2017

Greens Production Goes High-Tech at lēf Farms

A Finland-based company has developed two new automatic growing systems for lettuce heads and baby leaf lettuce. Learn how one grower is making it work for them.

Read More

December 9, 2017

Southern California Wildfires Narrowly Miss Most Grower…

Here’s an update on horticulture businesses in the areas affected by the California wildfires.

Read More
Monitoring the plant canopy for temperature

December 9, 2017

Infrared Thermometers for Monitoring Plant and Substra…

Growers use many tools to monitor the greenhouse environment. Learn about the best practices for using an infrared thermometer to measuring plant temperature.

Read More
Weigela Czechmark (Spring Meadow Nursery)

December 8, 2017

Spring Meadow’s New Logo Highlights Focus on New, Color…

In a move that highlights its commitment to developing new, colorful flowering shrubs, Spring Meadow Nursery has unveiled a new logo.

Read More
HortScholars

December 8, 2017

HortScholars Program Now Accepting Applications for 201…

Do you know any college students currently in a horticulture-related program? This unique program gives them a chance to connect with industry leaders and make new connections at Cultivate.

Read More
Peat vacuum harvester

December 8, 2017

The Sustainability of the Peat Industry Looks Better T…

Despite talk about alternative products and differences of opinion over its sustainability as a resource, peat is here to stay.

Read More
SunStanding-New-Guinea-Impatiens-Dummen-Orange-feature

December 7, 2017

Growing Tips From a Pro for SunStanding New Guinea Impa…

SunStanding New Guinea impatiens hybrids spruce up the landscape with vibrant blooms that explode with color in both sun and shade areas, and they hold up well in heat and humidity.

Read More
Japan-Airlines-princettia

December 7, 2017

Suntory Pairs Princettia with Several Breast Cancer Awa…

Suntory Flowers is partnering with several major brands to support breast cancer awareness and fundraising, using its bright-pink Princettia euphorbias as the ideal plant for Pink Ribbon promotions.

Read More

December 7, 2017

For the Record: Differing Opinions Are Healthy

With all of the changes happening in our industry, differing opinions are healthy. Let's open up the dialog and keep it real.

Read More
mycoapply-from-mycorrhizal-applications-feature

December 6, 2017

How Mycorrhizae Provide Value at Your Greenhouse or Nur…

Mycorrhizae create a connection between the roots of a plant and the surrounding growing media. This ultimately leads to better crop health through enhanced nutrient and water uptake.

Read More
Kellee O'Reilly

December 5, 2017

We Are Not Immune: An Open Letter to the Green Industry…

We’re an industry rooted in family values, farming, agriculture, passion for nature, and faith. We are also an industry made up predominantly of men in positions of leadership. During an interesting watershed moment that is happening culturally at present, it's important for the green industry to address its own issues.

Read More
GROW-Summit-2017-Group-Photo

December 5, 2017

GROW Summit 2017 Tackles Marketing and Business Managem…

This year’s think-tank style event brought together leaders from across the green industry to deliberate on topics such as disruptive marketing, cost accounting, and Millennials, to name a few.

Read More

December 5, 2017

Skagit Horticulture Builds New, Inclusive Business With…

By merging two large-scale producers, Skagit Gardens and Northwest Horticulture, the new company has realized its strengths through focused divisions that emphasize efficiency and success.

Read More