Protecting pollinators in orchards: Best management practices

GN-MR-3-POLLINATORS-ORCHARD-0621by Bill and Mary Weaver
Neonicotinoid insecticides have been getting some highly visible bad press because of misapplication, as happened in Oregon in June of 2013 when they were sprayed on linden trees in full bloom, resulting in a large, well-publicized bumblebee kill. The public was sufficiently concerned that in February of 2014 in Minnesota, protestors in bee costumes demonstrated at a Home Depot, asking the chain to stop selling bedding and nursery plants that had been sprayed with neonics. Retailers began asking greenhouse growers to either not use neonics, or to place labels on their bedding and nursery plants stating that neonics had been used in producing them, leading to the fear among growers that consumers would not purchase those plants because of negative perceptions.          
Although the EPA has been taking a conservative approach, activists filed lawsuits against the EPA for not banning neonics outright. “Growers need to make pollinator stewardship a priority, because they risk both lower crop yields, and the loss of important crop protection products down the line,” stated Julianna Wilson, Tree Fruit IPM Outreach Specialist in the Department of Entomology at Michigan State University. “We need an integrated approach to pest management that results in both the control of the target pests and diseases, while doing the least possible harm to bees and beneficials.”
Researchers have been finding that in addition to neonics, tank mixes with certain fungicides can be highly toxic to bees, and that varroacides used in hives can act synergistically with neonics to make them more damaging to bees. The use of Insect Growth Regulators has also been implicated in damage to bee populations following pollination in almonds. Neonics may also act synergistically with certain inert ingredients in insecticides. Neonics are, of course, highly toxic when sprayed directly on foraging bees. Residues (usually extremely small) of neonics used systemically have been detected in nectar and pollen.
Neonics used in seed treatments can persist in soil and surface water, and the planter dust may blow onto nearby flowering plants worked by bees, potentially poisoning brood. Residues taken up by woody plants can remain there for quite a while. If neonics are injected into the trunks of woody plants, they can still be found in those plants the following year. With all that said, however, Wilson stated, “In most instances, their use as labeled poses very little risk to bees, although growers may still be affected because of people who have an emotional stake in this.”
In April of 2014, Wilson convened a group in E. Lansing, MI to work out Best Management Practices for protecting bees in orchards. The group included EPA, orchard managers, various specialists, state apiarists, and university representatives. Here is a summary of the Best Management Practices the group decided upon, which are applicable across the country, with a few added comments by a beekeeper.
Before the hives are delivered:

  • Make up a written contract to clarify both the expectations of the grower and the beekeeper. The contract should include the number of hives to be supplied, expected hive strength, when they will be delivered, where they will be placed on the farm, and when they will be removed. The contract should also include expected record keeping by both grower and beekeeper. Jointly communicate any concerns when the contract is discussed and signed. Communication is important, from before hives are delivered until after they have been removed.
  • Talk to neighboring growers about where the hives will be placed, and the importance of not allowing pesticide drift into that area. Alert them when the hives have been delivered.
  • It can be a good idea to provide the beekeeper in advance with a list of sprays that will or may potentially be used while the bees are on site.

When the hives are delivered:

  • Pick a site for them that is upwind from potential spray drift and protected from sprays as much as possible.
  • Be aware that bees can and do fly 2 miles and farther, and don’t need to be placed in groups within the orchard or along driving rows for good pollination. A safe location outside the orchard will be best for everyone.
  • Together with your beekeeper, inspect the just-delivered hives for the contracted hive strength, remembering that if temperatures are warm enough for foraging, the number of frames covered with bees will be fewer than if it’s cold and all bees stay in the hive. This inspection is conducted both to make sure that substandard hives were not delivered, and also to prevent claims from later being made that they became substandard because pesticides while in the orchard injured them.
  • From before the hives are delivered until after they have been removed, keep and retain careful, accurate records of all pesticides used, in case there is a question later about whether all current label directions have been followed.
  • Don’t use Lorsban pre-bloom because of its long residual toxicity. Be sure correct timing is followed for Re-Entry Intervals when hives are delivered.
  • Select the least bee-toxic insecticides when possible.
  • Although some insecticides are permitted during bloom, avoid spraying them, as well as fungicides when possible, while the bees are flying. After sundown and below 55 degrees are the best times to avoid contacting foraging bees when spraying.
  • Avoid spraying when it’s windy. Turn off your sprayer when near hives. Note the calibrations on your sprayer to reduce drift. Use low-drift nozzles when possible. Also avoid spraying open flowers in adjacent areas, and use selective herbicides on flowering plants or mow flowers on the orchard floor before spraying.
  • Don’t leave water puddles contaminated by insecticides where the bees can find them and carry the water back to their hives. Avoid contaminating ponds and other bodies of water.
  • In the IMMEDIATE post bloom period, don’t use tank mixes containing any insecticides. Spray bee- toxic insecticides only after flowering is complete and all petals in the orchard have fallen.

After bloom, make sure hives are removed as agreed upon. Continue to keep flowering plants in the orchard selectively herbicided or mowed. Plant bee-attractive flowering plants or a field of flowering buckwheat, if possible, so these flowers will be available for post-bloom foraging to divert wild bees from future orchard sprays. Such plantings will also help to sustain both bumblebees and wild solitary bees, some of which may have multiple generations and may help to improve on the pollinating efficiency of honeybees by giving better cross-pollination between rows. Cost sharing for such plantings may be available from several sources. Check with your Extension Agent.

2015-05-04T12:44:10+00:00May 4, 2015|Grower West|0 Comments

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