May 13, 2015

Keep bee safety in mind during orchard bloom

Protecting pollinators against pesticide exposure by paying attention to when bees are active is one of the most important steps tree fruit growers can take as part of a sound integrated pest management (IPM) plan. Two other important steps growers should take are to prevent drift onto non-crop flowering plants, and provide flowering habitat out of the way of potential pesticide drift after crop bloom.

Tree fruit growers need the services of bees to move the pollen necessary to initiate fruit. While pollination alone does not guarantee a marketable crop, pollinator stewardship is an important component of tree fruit IPM. An IPM plan is a set of best management practices that rely on what we know about the biology of a cropping system and how it interacts with the environment to select and implement management strategies when they will be most effective against a particular pest, and do the least harm to humans and the environment.

Michigan State University Extension has developed a summary of best management practices for pesticide use and bee safety in orchards.

Pre-bloom

Draft a written contract with your beekeeper to clarify expectations on both sides, including record keeping, when the hives will be delivered, where the hives will be placed on the farm and when they will be removed. Keep good records of all pesticide applications so that if a complaint arises, the record shows that everything was done according to label.

Provide sufficient time between pre-bloom sprays and placement of hives to avoid exposing bees to lethal residues. Remember that re-entry intervals (REIs) on pesticide labels should not be violated by a beekeeper placing colonies or removing them from your crop.

When honey bees are delivered

Select a location for hives on the farm that is protected from potential spray drift. Honey bees are highly mobile, so for maximum safety, hives should be placed on the perimeter of plantings rather than along drive lanes within the planting. Make sure that pesticide applicators know where these locations are so that they can be avoided.

In the company of the beekeeper, examine delivered hives to know the health and strength of the hives you are renting. Hives with six to eight frames containing 70-75 percent brood per frame are considered to be a reasonable expectation at the beginning of pollination season in Michigan.

During bloom

At all times, follow the current label for pesticides being applied. New EPA pesticide labels have bee-specific language and it is anticipated that more pesticide labels will include bee-specific labeling in the future. Select pesticides that are least toxic to bees whenever possible.

Provide notice of planned pesticide applications so that the beekeeper has time to close hives if he or she feels the need to do so prior to an application. Avoid applying insecticides permitted for use during crop bloom while bees are foraging, and avoid tank-mixes that include insecticides to control pests in the immediate post-bloom period – even when not labeled as bee toxic.

Bees are less active in cool temperatures and low light, so spraying pesticides after sunset can greatly reduce the risk of direct exposure, as can spraying when temperatures are below 55 degrees Fahrenheit. Drift prevention should include turning off the sprayer near hives, avoiding spraying under windy conditions and using equipment calibrated or designed to produce low drift.

Clean equipment and dispose of pesticide products safely – do not leave contaminated water where bees can access it. Prevent pesticide contamination of open water sources that bees might use consume for regulating in-hive temperatures.

Petal-fall and post-bloom

Do not apply bee-toxic insecticides until crop flowering is complete and all petals have fallen; if you are unsure whether bees have finished foraging in your crop or not, spray after sunset or when air temperatures are below 55 F to minimize exposure of remaining bees to pesticides. Use selective herbicides to eliminate flowering weeds from drive lanes or mow before spraying to reduce flowering weeds in the orchard.

Provide non-crop flowering plants elsewhere on the farm to divert bees from fruit plantings (i.e., meadows that contain bee-attractive plants or summer-flowering cover crops like buckwheat) and prevent drift of pesticides off target.

— Julianna Wilson, Michigan State University Extension, Department of Entomology