Ongoing field trials are demonstrating that planting honey bee forage crops in and around almond orchards show promise in improving overall health of honey bee colonies.

Some 1.5 million honey bee colonies are brought to California annually to pollinate the state’s almond crop. Commercial bee colonies begin arriving in California almond-production regions in October and are moved into orchards to begin pollination in February.

There is a shrinking supply of good food sources for these honey bee colonies overwintering in California. Changing crop patterns, loss of nectar sources and urbanization have combined with other factors to seriously affect available food sources for pollinators in the winter. This dynamic is impacting the overall health of honey bee hives, which depend on a diverse food supply to thrive, and directly impact almond pollination in early spring.

(For more, see: Bees bring in $29 billion for US farmers)

Trials initiated in fall 2011 aim to develop strategies for providing supplemental food resources for honey bees before and after almond bloom in California through planted bee pasture. The trials are funded by a Specialty Crops Grant through the California State Beekeepers Association (CSBA) and managed by Project Apis m. (PAm), a non-profit research group funded by growers and beekeepers to enhance the health of honey bees and improve crop production potential.

These ongoing trials are looking at the potential for planting native and non-native flowering plants such as mustards, legumes and regional wildflower mixes either as cover crops or between trees in the interior of orchards, outside orchards along perimeters or margins, or along access roads and waterways.

Demonstration plots last year throughout California almond growing regions in Glenn, Colusa, Stanislaus and Kern Counties illustrated some of the potential benefits and suggested practices for planting honey bee forage near almond trees.

In Glenn County, grower cooperators planted various mustard species and broadleaf forb mixtures on a total of 150 acres of land adjacent to almond orchards. Seeds were planted on soils that do not support almonds, but are ideal as supplemental pollinator habitat. Despite difficult growing conditions, the flowering plants ultimately thrived and provided post-almond-bloom nectar and pollen sources for honey bees.

(For more, see: California beekeeper driven by passion, pollination and quality)

Among the lessons learned from that northern California trial are:

• Growers should commit sites to at least a two-year plan so that invasive weeds can be controlled by disking, mowing or herbicides;

• Seeds should be planted prior to the first germinating rain to optimize growth and give seeds a competitive advantage over weeds; and

• Growers should consider non-native plant species, such as robust non-native legumes, as well as native flower sources. 

At the Nickels Soil Lab in Colusa County, trials with seed mustard, canola and clover along orchard margins and access roads showed similar promise. Honey bees thrived on annual clover cover crops and other seed mixes planted within almond orchards at the research site.