Posts Tagged: alfalfa
Across the globe, scientists have shown that birds can be farmer allies. Insectivorous birds feed on damaging insect pests in many crops including coffee, cacao, oil palm, corn, cabbage and apples. Raptors, including hawks and barn owls, feed on rodents, including gophers, voles and mice (see blog, Barn owls help clean up rodents naturally).
Despite this deep historic knowledge that birds are important predators of crop pests, over time the perception of birds as natural enemies of pests has been generally replaced with the idea that birds are often major crop pests themselves. Indeed, some bird species — like some types of insects — can cause trouble for farmers, but many others — especially those that eat insects and rodents — can be beneficial.
Do birds control insect pests on farms in California's Central Valley?
They do! Recent studies by Dr. Sacha Heath, UC Davis, and Rachael Long, field crops and pest management advisor, UC Cooperative Extension, showed that birds help control insect pests in walnut orchards. Dr. Sara Kross (UC Davis postdoctoral alumnus, now with Columbia University) showed that birds help control alfalfa insect pests.
Birds are voracious predators of codling moth pests in walnuts
Codling moth is a major worm-like pest that infests walnuts, apples and pears. The larvae go dormant during winter, living in cocoons in crevices in trees. Adult moths emerge in the spring, lay eggs and infest crops.
We evaluated bird predation of codling moth using “sentinel prey” and exclosure cages. We glued codling moth cocoons to walnut trunks and covered them with cages, allowing insects and spiders to access the cocoons, but not bird predators. This allowed us to count how many larvae were eaten inside and outside of the cages to estimate pest reduction by birds.
What did we find?
Natural enemies, like parasitic wasps and lacewings, alone reduced codling moth larval numbers by 11%; adding birds into the pest control system reduced them by 46%! Nuttall's woodpeckers and white-breasted nuthatches did a lot of the work; these birds travel up and down the trunks of trees, searching for insects.
Above, a white-breasted nuthatch preys on a codling moth larva “sentinel cocoon” on a walnut tree. Video by Sacha Heath.
Alfalfa weevils are no match for insectivorous birds
Alfalfa weevils are key pests of alfalfa, reducing yields and hay quality if left uncontrolled. Dr. Sara Kross looked at bird predation of this pest by excluding birds from alfalfa plants via cages, and counting the number of weevils inside and outside the cages. She found that birds reduced the number of weevils by more than 30%, showing their importance in helping to protect alfalfa from this serious pest.
Does field edge habitat, like hedgerows, help attract beneficial birds?
Yes! Hedgerows are important habitat for beneficial birds, serving as nesting, foraging and roosting sites. In a study in the Sacramento Valley, crop margins with hedgerows, tree lines and riparian buffers harbored up to six times more birds and up to three times more bird species than bare or weedy margins.
Walnut orchards adjacent to hedgerows and riparian areas had higher numbers of beneficial birds along with more species. In alfalfa, there were more beneficial birds in fields when at least two tall trees were present along the field edges. More beneficial birds were associated with better pest control, that is, fewer codling moth cocoons and alfalfa weevils.
Birds have large territories, fly long distances, and are influenced by what happens on the farm as well as by what happens in the landscape around the farm. For example, we found that codling moth predation by birds greatly increased in walnut orchards as the amount of habitat in the landscape around the orchards increased (including hedgerows, tree lines, riparian and oak woodlands, and grasslands).
Will hedgerows increase the numbers of pest birds?
Pest birds are present on farms regardless of field edge habitat (such as weedy vegetation or hedgerows). Cases will be different, depending on the crop, but in the fields and orchards of Yolo County, researcher Hillary White (formerly with UCCE and now with U.S. Fish and Wildlife) found that three of the most common avian crop pests (American crow, red-winged blackbird and Brewer's blackbird), were up to 10 times more abundant in agricultural fields with bare or weedy margins than in fields with hedgerows.
What can I do to attract beneficial birds to my farm?
Our avian research team has been quantifying the conditions under which birds are helpful or harmful to growers. We are looking for ways to help farmers create bird habitat on their farms to harness the beneficial pest control services birds can provide, while also protecting crops from the damaging effects of some bird species. This information is available in the new publication “Supporting Beneficial Birds and Managing Pest Birds,” co-authored by the Wild Farm Alliance and Drs. Kross and Heath, and technically advised by UC Cooperative Extension and several farmers. This is a user-friendly guide for farmers and conservation practitioners, with the goal of co-managing farmlands for biodiversity and farming.
A white-breasted nuthatch preys on a codling moth larva “sentinel cocoon” on a walnut tree. (Video still: Sacha Heath)
Because periodic droughts will always be a part of life in California, the UC California Institute for Water Resources (CIWR) produced a series of videos to maintain drought awareness and planning, even in years when water is more abundant.
The final video of the three-part series, which focuses on drought strategies for citrus, was launched April 6 on the UCTV Sustainable California channel. The first episode, which centered on alfalfa production, premiered Feb. 2 on the UCTV Sustainable California channel. The second video, on almonds, was launched March 2 on Sustainable California. A trailer with clips from all three episodes is here.
The videos are inspired by a collection of 19 drought tips produced by CIWR in collaboration with UC Agriculture and Natural Resources researchers during the drought of 2010-16. The tips cover a broad spectrum of California crops, from alfalfa to walnuts. Topics also include salt management, use of graywater in urban landscapes, and the use of shallow groundwater for crop production.
The drought tips collection and the drought tip videos were sponsored by the California Department of Water Resources. Following are links to each of the videos:
The CIWR drought tip series opens with Cannon Michael of Bowles Farming in Los Banos. The alfalfa grower works with UCCE specialist Dan Putnam. “There's a lot of misunderstanding about alfalfa as a crop,” Michael said. “It does take water to grow it, as with anything, but you get multiple harvests of it every year.”
The second episode features almond producer Raj of Meena farms. He works with David Doll, UCCE advisor in Merced County. “One positive of this drought,” Meena said, “is that it has forced us all to be more efficient in how we use our water.”
The series finale features Lisa Brenneis of Churchill-Brenneis Orchard in the Ojai Valley of Ventura County. She worked with UCCE advisor Ben Faber to install a new water-efficient irrigation system. “Irrigation is the only job we really have to do,” Brenneis said, “and we have to get it as right as we can.”
For a complete list of drought tips, see http://ucanr.edu/drought-tips.
“The overseas market is extremely important,” said Jesús Ramos, a Tulare County citrus farmer. “That dictates whether you can keep a crop going or not.”
Another key to keeping crops going is the state's water situation. After four years of drought, Californians are hoping the predicted El Niño rains will live up to the forecast.
Wee interviewed UC Agriculture and Natural Resources alfalfa expert Daniel Putnam, a UC ANR Cooperative Extension specialist based at UC Davis. He said U.S. alfalfa hay exports to Asia and the Middle East have climbed in recent years. China's imports have risen from almost nothing in the mid-2000s to roughly 1 million metric tons forecast for 2015.
A University of Arizona water resource expert, Robert Glennon, told the reporter he was surprised to learn that 2 million tons of Western alfalfa hay, which required 100 billion gallons of water to produce, was shipped overseas.
“When I found out we were shipping bales of hay across the world, you could have knocked me over with a feather,” Glennon said.
One of the export drivers is cheap shipping to Asia in containers that might otherwise make the return trip across the Pacific Ocean unfilled. Putnam estimates shipping hay from the Imperial Valley to Tulare County can run $60 to $70 per ton. But transporting the hay from Long Beach to a port in Asia costs $25 to $45 a ton.
The director of UC ANR's Agricultural Issues Center, Daniel Sumner, was one of three guests on the one-hour talk radio program Your Call, which was broadcast on KALW, Local Public Radio in San Francisco. The topic - How would reducing our intake of meat and dairy affect the drought? - was prompted by off-the-cuff comments made by Gov. Jerry Brown in June. Answering the question, "Is part of the drought strategy to reduce meat consumption?" Brown replied, "If you ask me, I think you should be eating veggie burgers."
On the Your Call show, Sumner explained that beef consumption has little impact on the California drought.
"I do want to make clear, when it comes to water embedded in any product, it depends where the water is from," Sumner said. "We feed cattle in California with grain from the Midwest."
Dairy production is another issue. "Dairy cows are fed lots of grain, soybeans and canola coming from Canada and the Midwest, but also silage and alfalfa, much of which is from California. California dairy is a drought water issue. Beef really isn't."
UC ANR Cooperative Extension specialist Dan Putnam appeared on the KTVU Evening News to discuss alfalfa water use with reporter Ken Wayne. Putnam said the drought has hurt the state's alfalfa industry.
"Statewide, it's been fairly devastating," Putnam said. "We're at the lowest acreage we've seen probably since the 1930s."
He also noted the importance of the crop, a key part of dairy cattle's diets.
"An average field of alfalfa produces approximately 2,400 gallons of milk per acre," Putnam said.
The drought is forcing farmers to reexamine the way they water their crops, but converting to drip irrigation in alfalfa is unlikely to be widely implemented, reported David Wagner on KPBS Radio News.
The drip irrigation system conserves water - almost by half, said farmer Jack Cato - but is expensive and requires regular maintenance. After six years, the drip system is yet to pay for itself.
"Drip irrigation is not the answer for everything," said Khaled Bali, irrigation advisor with UC Agriculture and Natural Resources (UC ANR). "I would not recommend switching every acre in the Imperial Valley to drip irrigation."
Cato added that new drip irrigation users face a steep learning curve.
"Whatever farm starts doing this, he needs to take baby steps," Cato said. "It's not something you learn overnight, or in a book. You have to study your fields daily."
For more on water use and alfalfa, see Why alfalfa is the best crop to have in the drought by Daniel Putnam, UC ANR Cooperative Extension specialist based at UC Davis, in the Alfalfa & Forage Blog.