Honey bee colonies, pollination, bee safety, and beekeeper responsibilities

Joseph Connell, UCCE Farm Advisor Emeritus, Butte County and Emily J. Symmes, UCCE Area Integrated Pest Management Advisor, Sacramento Valley and Statewide IPM Program

Always be aware of honey bees when they’re in your orchard to pollinate your crop. After all, you’re paying good money for the bees to do a critical job! You can go a long way toward protecting the health of honey bee colonies by avoiding contamination of pollen and pollen foragers and by avoiding products with potential toxicity to honey bees or their larvae while bees are in your orchard. This is good husbandry and it’s in the interest of both the grower and the beekeeper.

Honey bee pasture.  Lack of blooming pasture while bees wait for almonds to bloom can weaken colonies. Although it’s too late to plant a honey bee forage mix that will bloom before almonds this year, if you have an open field, new orchard, ditch banks, field margins, or a neighboring prune or walnut orchard where a winter cover would be beneficial, you might consider planting an early-blooming forage mix containing mustard next fall. When planted in late summer or early next fall, it may provide flowers ahead of almond bloom in 2021 that can help with honey bee nutrition. Some cover crop seed providers have mixes particularly geared towards almond bloom timing. Almond flowers are so rich in rewards for bees that once almonds begin to bloom, flowers in cover crops are a minimal distraction for pollination.

For almond pollination a colony should have an active brood nest with uncapped worker brood at the start of almond bloom. Bees feed pollen to developing larvae so open brood cells indicate the hive has a demand for pollen. When pollen is in demand in the hive, more pollen foragers are sent into the field to collect pollen. Hives should be moved into orchards before the earliest blooming variety is at 5% bloom. Once 100% of flowers on the latest blooming variety have shed their pollen and are starting petal fall, hives should be moved out.

Honey bee colonies.  The general recommendation is to have between 2 and 3 hives per acre for pollination with a minimum of 8 frames of bees per colony. Under adverse weather conditions weaker colonies may not field enough workers to provide adequate pollination. Beyond about 12 frames of bees, increased colony size doesn’t seem to increase foraging. Dr. Robin Thorp at UC Davis developed a method that used cluster size observations to make a rapid honey bee colony strength evaluation. Five years of work comparing cluster observations with intensive frame by frame counts led to this quick evaluation system.

In self-fertile variety orchards there is speculation that fewer colonies will be needed to set an acceptable crop. Some have suggested that ½ to 1 hive per acre should be sufficient.  Dr. Elina Niño, Apiculture Extension and Research at UC Davis, is beginning to study the number of colonies needed for optimum production in self-fertile orchards.

Plan ahead to make sure you have bees for pollination. You and your beekeeper should settle on a written contract so both parties know what is expected. It should include such things as when bees are moved into and out of the orchard, placement of colonies, minimum colony strength, and possibly price based on the number of frames of bees per colony.  For the best bee health and successful crop pollination it’s important that all beekeepers and almond growers talk to one another and work together for everyone’s benefit.

Beekeeper requirements.  California Food and Agriculture Code laws require that all beekeepers who move bees into the state or come into possession of an apiary must register with the appropriate County Agricultural Commissioner. Hives must be identified by displaying the owner’s name, address, and phone number. Any apiary operator must notify the County Agricultural Commissioner if a colony of bees is relocated within the county. The County Agricultural Commissioner must be notified within 72 hours if a beekeeper relocates a colony of bees from one county to another.

A new program called BeeWhere is in place to help protect bees from pesticide applications. BeeWhere offers a dynamic, real-time GIS mapping system where beekeepers with a BeeWhere beekeeping ID can mark hives with a simple pin drop on a map. This program brings beekeepers and pesticide applicators together by tracking and safeguarding hive locations across California. All registered bee hive locations are stored securely within the California Agricultural Commissioners database system (CalAgPermits), and are not shared with anyone outside the California Agricultural Commissioners staff.

BeeWhere integrates with crop management tools like Agrian and CDMS that are used by Pest Control Advisers (PCA), growers and licensed applicators in the state. These crop management tools interface with BeeWhere to access the general number of hives within a mile of a site when a PCA is considering a pesticide for crop management and allows applicators to contact beekeepers for notification purposes. Only verified growers and applicators get access to beekeeper contact information. Beekeepers choose the method of contact and have the option to remain anonymous. Check with your beekeeper and encourage them to use this new system to protect the safety of the almond pollinators you’ve paid dearly to see working in your orchard!

Bloom Sprays.  Avoid insecticides when honey bee colonies are in the orchard. The only insect pest that could potentially be considered for treatment when honey bees are in the orchard is peach twig borer (PTB).  The only viable option to manage PTB at bloom and petal fall is Bacillus thuringiensis (Bt), known to be non-toxic to honey bees. More detail on PTB management using Bt, and alternative treatment timings are available at: ipm.ucanr.edu/PMG/r3300211.html.

Fungicides.  If the weather is dry and clear during bloom, conditions not conducive to disease development, UC pathologist Dr. Jim Adaskaveg suggests making a single delayed bloom application at 20 to 40% bloom.  Under wet bloom conditions, multiple bloom fungicide applications are necessary. Treat only for pathogens that are a potential threat in your orchard and are best controlled during bloom. The online UC IPM guidelines (ipm.ucanr.edu/PMG/selectnewpest.almonds.html) provide details on monitoring and treatment timings for key almond diseases.

Adjuvants.  According to the authors of the annual Fungicides, Bactericides, And Biologicals for Deciduous Tree Fruit, Nut, Strawberry, And Vine Crops (Adaskavag, Gubler, and Michailides 2017, ipm.ucanr.edu/PDF/PMG/fungicideefficacytiming.pdf), “most fungicides are formulated with adjuvants including wetting agents, spreaders, and stickers. Unless a material specifically indicates on the product label that an adjuvant should be added, the fungicide product does not need additional adjuvants mixed into the sprayer tank to improve performance. With few exceptions, adjuvants do not statistically improve the efficacy of fungicides for managing diseases of fruit and nut commodities.”

All University of California efficacy trial results (+++’s in the efficacy table) are based on this premise and materials are tested without addition of adjuvants unless expressly indicated on the product label. Adjuvants may increase the potential toxicity of fungicides to honey bees. To save money and protect bees, only put what is absolutely necessary in the tank.

Choosing materials.  Know the impacts of particular fungicides on honey bees by visiting the University of California IPM Program’s “Bee Precaution Pesticide Ratings” at ipm.ucanr.edu/beeprecaution/. These precaution rankings (I, II, III) have been created based on all of the currently available scientific studies, including adult bee toxicity and effects on bee brood. Use the information contained here conservatively and always proceed with caution (err on the side of bee safety).

“Bee-safe” applications.  Apply fungicides when available pollen is at the lowest possible level (late afternoon through very early the following morning). Pollen is released in the mornings when temperatures reach 55°F, and is often removed by foraging honey bees by mid-afternoon. The “bee-safest” time to apply fungicides is in the evening or at night when temperatures are less than 55°F.

Take precautions to never spray hives or bees directly with any material. Contaminated foraging worker bees carry the fungicide back to the hive where other worker bees clean them and contaminate the hive’s food supply. Aside from these toxicity concerns, bee flight ability can be impacted from the weight of any spray droplets. Water application from sprays or rain can cause pollen grains to burst, damaging pollination.