Honey bees are necessary for the pollination of fruit trees. Orchardists must make a sincere effort to protect them.
Even though pesticides are applied to orchard trees, some of the spray may settle on blooming broadleaf weeds in the cover crop and kill foraging honey bees. The following precautions will help prevent bee kills and ensure adequate pollination:
- Do not place honey bees in an orchard until blossoms are open. This will help minimize the number of bees foraging on blooming weeds in the cover crop.
- Application of insecticides to blossoming orchards can kill foraging honey bees. Insecticide residues on blooming broadleaf weeds in orchard cover crops can also cause bee kills. Never apply insecticides that are hazardous to bees (see following table) when any blossoms are open in the orchard, or allow insecticide drift onto blooming weeds in cover crops, or onto adjoining orchards that are blossoming.
- Controlling blooming broadleaf weeds (e.g. clover, dandelion, mustard) in orchards is an essential part of preventing honey bee kills. Mow or beat down orchard cover crops before applying sprays hazardous to bees - especially Actara (thiamethoxam), Clutch (clothianidin), Lorsban (chlorpyrifos), and Sevin (carbaryl). Blossom removal is especially important in relation to the first cover spray on apples. Treatment is applied during a critical foraging period, when bees will fly several miles when temperatures are higher than 50°F to obtain pollen and nectar from even a few blooms of dandelion. Using a labeled herbicide to eliminate broadleaf weeds from cover crops will help to prevent bee kills.
- Many insecticides commonly used in orchards are highly toxic to honey bees and are hazardous to bees for several days. This includes insecticides like Actara (thiamethoxam), Clutch (clothianidin), and Lorsban (chlorpyrifos). Some formulations of Sevin (carbaryl) are also hazardous to bees for several days.
- Proper timing can help to minimize the potential for honey bee kills if the insecticide has an intermediate or short residual hazard to bees. Cool temperatures and higher insecticide use rates can greatly lengthen the residual hazard. Spraying at night will not prevent a bee kill if the insecticide has a long residual hazard to bees.
- In general, herbicides and bioregulators (except Sevin (carbaryl)) are relatively low in toxicity to bees.
- Certain fungicides, including captan, Rovral (iprodione), and ziram, are harmful to honey bee larvae when applied to bloom.
- The orchardist must know who owns the honey bees in the orchard and where the beekeeper can be contacted. Beekeepers should place their name and phone number on hives to identify them.
- Beekeepers must register their honey bees with the Washington State Department of Agriculture, Plant Protection Division. To request an apiary registration form, call 360-902-2070. For technical questions regarding the effects of pesticides on bees, call 360-902-2078.