Crop & Pest Report


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Protect Pollinators - Wise Insecticide Use (08/02/18)

Bees are in trouble in the United States and other areas of the world.

Protect Pollinators - Wise Insecticide Use

Bees are in trouble in the United States and other areas of the world. Native bee species are declining in numbers due to habitat loss, pesticides and other factors. Approximately one-fourth to one-third of European honey bee colonies in the U.S. die each year despite the best efforts of their attentive beekeepers.

An Integrated Pest Management (IPM) approach should be used to promote judicious use of pesticides for pest control only when needed and to implement scouting, use of economic thresholds and non-pesticide pest management strategies, such as cultural, biological control or host plant resistance.

Remember, most of our insecticide used in field crops are broad-spectrum insecticides. Any broad-spectrum insecticide can kill ‘all’ insects, including bees and natural enemies of the targeted insect pest. Choose the least hazardous formulation of an insecticide product for bee safety (Table 1).

Application is recommended in the late evening (after sunset) or when temperatures are below 55 F, when most bees are not actively foraging. Remember, some bees such as bumblebees forage in cooler temperatures (up to 50 F) and are actively foraging in the early morning, much longer than honeybees.

Use short-residual insecticides. If possible, ‘spot’ treat instead of broadcast spraying to minimize the area treated with insecticide, especially for edge insect pests, such as young grasshoppers that do not move very far from their egg hatching sites.

Remember to use all pesticides in a manner consistent with the label. Always read, understand and follow the pesticide’s label directions in regards to pollinator protection. Some pesticide labels require applicators to notify beekeepers 48 hours prior to applications to blooming crops (or if flowering weeds are present in fields).

Pesticides that have the honeybee hazard icon (on right) on the label indicate that this product is highly toxic to bees and specific application restrictions apply to protect pollinators. An example of an acutely toxic substance to bees is the active ingredient imidacloprid or chothianidin in the neonicotinoid insecticide group, IRAC 4A (systemic insecticides).

Finally, know and communicate with your local beekeepers if you need to spray flowering sunflowers or other flowering field crops for insect pests. Please PROTECT honeybee colonies by notifying beekeepers before an insecticide application (at least a 48 hours notice), so they can move or cover up their hives before the application.

To find beekeepers, see the North Dakota Bee Map on the North Dakota Department of Agriculture website. Zoom in on the area of interest to find names and contact information of local beekeepers. Please read our North Dakota Pollinator Protection Plan from the North Dakota Department of Agriculture.

A NDSU Extension YouTube video is available on Protect Bees from Pesticide Poisoning.

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Janet J. Knodel

Extension Entomologist

This site is supported in part by the Crop Protection and Pest Management Program [grant no. 2017-70006-27144/accession 1013592] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed are those of the website author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

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