alyssumand almonds

Planting bee forage cover crops in San Joaquin Valley

Bees run out of primary seasonal employment after petal drop and run low on food due to sparse forage. This year, several proactive farmers planted a mix of cover crops to meet this need. NRCS can help growers with honey bee and pollinator health through plantings (cover crops, hedgerows).

The constant buzzing of bees, rushing from one almond flower to the next, is quiet now after this spring’s almond pollination season in California’s San Joaquin Valley (SJV). The trucks rolled out, loaded with more than a million bee hives, destined for home on the Great Plains or other pollination jobs in California citrus orchards. 

When the almond petals drop, the bees run out of primary seasonal employment and run low on food as forage is sparse in the SJV. It would have been no different this year in Madera County if it were not for proactive farmers who planted a mix of cover crops to meet this need.

When Brett Adee of Adee Honey Farms came to Grewal Brothers Farming to pick up his hives this spring, he surprisingly saw his bees snacking on a mix of mustard, clover, and alyssum flowers which Gurdial Grewal had planted the previous fall.

Adee quickly decided to leave the bees on site a few more weeks to take advantage of the bloom.

“Wonderful” is how Adee described the cover crop pollen. “It keeps the bees healthy for the next season.”

If Adee’s bees were not gathering mustard pollen at Grewal’s, they would have fed on supplements until the weather in South Dakota allowed him to move the bees there for forage.

“The supplements just maintain them; they don’t keep them nice and robust,” he added.

Seeds for Bees

Grewal’s free cover crop seed came from the Seeds for Bees project through Project Apis m. (PAm).  PAm is a non-profit named after the European honey bee and is dedicated to enhancing the health of bee colonies while improving crop production.

The group has been funding bee research for many years. This year, PAm began offering the free seeds to producers to plant near almonds where honey bee hives are stationed. The project aims to improve bee health by increasing forage in California.

“Pollen is the best food for the bees,” said Meg Ribotto of PAm.

These cover crops are chosen for their ability to bloom before or after the almonds, extending the time pollen is available to the bees.

The project is funded through fall 2015 through state and private funding. In 2013, 158 almond growers participated and 2,500 acres of PAm seed was planted.

Grewal selects seed

Grewal chose several seed mixes from the PAm options. He was pressed for time last fall so he combined all the seed into a single mix including three mustard species, daikon radish, vetch, alyssum, and four clovers for one very diverse cover crop.

Grewal planted the mix between the rows of almonds, peaches, pistachios, and grapes. He included some of the sandiest ground on the ranch to build organic matter and improve water holding capacity and soil fertility.

“You’re doing two things - helping the bees and the soil,” he said.

When considering a flowering cover crop, almond growers may be concerned about the presence of competing blooms on the orchard floor. The University of California Cooperative Extension (UCCE) advises mowing groundcover to remove this competition during the almond bloom and for frost protection in the orchard.

David Doll, UCCE pomology farm advisor, says guidelines are established for the worst case scenario. In a good year with ample bee hours (times of favorable flying conditions for honey bees), he expects bloom competition effects to be insignificant. If it is windy, rainy, or cold, mowing would maximize the few bee hours available.

If growers simply do not want any bloom overlap, they can mow the cover crop during the almond bloom. The main goal of PAm is a longer blooming season before and after the almonds.

“Any extension of the forage season will benefit the hives,” Ribotto said. 

In his Almond Pollination Handbook, Joe Traynor of Scientific Ag Company recommends a field check for bloom competition.

Morning checks

“To determine if your covercrop is reducing or increasing almond pollination, check bee activity on your cover crop versus bee activity on your trees during the morning hours,” Traynor said.

“If there are significant numbers of pollen-collecting bees (those that store pollen on their back legs) on the cover crop, then it should be mowed. If nectar-collecting bees are working the cover crop, this will be beneficial since it will increase almond pollen collection.”

Gordon Wardell, Paramount Farming Company bee biologist, has used this type of field checking and has seen little competition.

“When I got to Paramount, I saw fields of wildflowers blooming adjacent to the almond orchards and a tractor disking them up.”

Wardell questioned the practice and investigated at the flower level.

“When we looked at the field at 10 a.m., the bees were busily working the almond blooms and almost no bees were in the wildflowers. By 4 p.m., the bees had stripped the almond flowers of their pollen and were in the field working the wildflowers. Few flowers that bloom at that time of year can compete with the abundance and attractiveness of almonds in bloom.”

Flowering cover crops can even cause colonies to ramp up pollen foraging. Wardell explains this positive feedback loop.

More larvae

“You want the colonies foraging. The more protein they get then the more larvae they will produce. The larvae produce a chemical called brood pheromone that tells the colony to forage for more pollen. The stronger the brood, the stronger the brood pheromone, and the more pollen foragers there will be. Supplemental pollen helps create more brood and consequently more demand in the almonds.”

Madera County almond producer Casey Bellach of Casey Bellach Farm Management planted the PAm clover mix into his first leaf almond orchard. He plans to let the clover and alyssum re-seed before mowing.

“I highly recommend growers plant bee forage cover crops,” Bellach said. “Honey bees are brought into orchards and expected to pollinate our almonds, but are left with nothing to work during the pre-and post-bloom periods.”

He added, “This causes stress on the hives that can be alleviated by providing forage. I’m a believer in cover crops in general. The free seed meant I didn’t have to spend a fortune, and the bees really like it.”

Bee specific

Cover crops are just one method for strengthening honey bee colonies. Bees also need good hive locations, water sources, and need protection from sprays which could negatively impact their health.

University of California Extension, PAm, and the Almond Board of California have information available for almond producers in caring for bees in the orchards.

PAm is signing up growers for Fall 2014 cover crops.

For more information, go online to [3] or order by email at [email protected] [4].

The Natural Resources Conservation Service (NRCS) can assist growers with promoting honey bee and pollinator health through plantings (cover crops, hedgerows) and management. Financial assistance is also available.

(Pricilla Baker is a NRCS soil conservationist based in Madera, Calif. - (559) 674-4628, Ext. 115 and [email protected] [5].)