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Posts Tagged: alfalfa

Birds are beneficial too!

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.

Western bluebird eating a caterpillar pest. Image by Glen Bartley/VIREO.
Western bluebird eating a caterpillar pest. (Photo: Glenn Bartley/VIREO)

 

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.

 

Codling moth larva feeding on walnuts. During winter, the larvae form cocoons and live the bark of trees.
Codling moth larva feeding on walnuts. During winter, the larvae form cocoons under bark flakes and in crevices of orchard trees.
 

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.

 

Codling moth larva cocoon in a cage, excluding birds. Image by Sacha Heath.
Codling moth larva cocoon in a cage, excluding birds. (Photo: Sacha Heath)

 

Codling moth larva cocoon outside a cage, eyed by a northern flicker, a predator of codling moth pests. Video still by Sacha Heath.
Codling moth larva cocoon outside a cage, eyed by a northern flicker, a predator of codling moth pests. (Video still: Sacha Heath)

 

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.

 

Bird exclusion cages were used to show that birds feed on alfalfa weevils, helping to protect alfalfa from this key insect pest. Image by Sara Kross, Yolo County alfalfa field.
Bird exclusion cages were used in a Yolo County alfalfa field to show that birds feed on alfalfa weevils, helping to protect alfalfa from this key insect pest. (Photo: Sara Kross)

 

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.

 

A native plant woody hedgerow in Yolo County, California. Image by Sacha Heath.
A native plant woody hedgerow in Yolo County, California. (Photo: Sacha Heath)
 

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).

More habitat in agricultural landscapes (such as riparian habitat along Cache Creek, left) brought in more beneficial birds to farms compared to less habitat (right). Google Earth image.
More habitat in agricultural landscapes (such as riparian habitat along Cache Creek, left) brought in more beneficial birds to farms compared to less habitat (right). (Image: Google Earth)

 

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.

A red-winged blackbird in winter wheat, Yolo County, California. Image by Sacha Heath.
A red-winged blackbird in winter wheat, Yolo County, Calif. (Photo: Sacha Heath)

 

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 loggerhead shrike, an insect predator, perches on elderberry on a Sacramento Valley farm.  Image by Sacha Heath.
A loggerhead shrike, an insect predator, perches on elderberry on a Sacramento Valley farm. (Photo: Sacha Heath)

 

Dr. Sacha Heath received her PhD from UC Davis's Graduate Group in Ecology and will soon be starting a postdoctoral fellowship with the Living Earth Collaborative in St. Louis, Missouri.

A white-breasted nuthatch preys on a codling moth larva “sentinel cocoon” on a walnut tree. (Video still: Sacha Heath)
A white-breasted nuthatch preys on a codling moth larva “sentinel cocoon” on a walnut tree. (Video still: Sacha Heath)

A white-breasted nuthatch preys on a codling moth larva “sentinel cocoon” on a walnut tree. Video still by Sacha Heath.

Posted on Wednesday, April 24, 2019 at 8:37 AM
Tags: alfalfa (36), birds (9), hedgerows (9), IPM (41), orchards (3), Rachael Long (39), Sacha Heath (1), walnuts (21)

Weed control in alfalfa, Canada thistle and Scotch thistle... oh my

Farm Advisors Update 2019-Feb

The February 2019 issue of the Farm Advisor's Update by Tom Getts (Weed Ecology and Cropping Systems Advisor) is out. Contents: Winter Annual Weed Control in Alfalfa (Avoiding Crop Injury with Roundup) Purple Flowers, Pokey Leaves and Deep Roots: Canada Thistle Control Trial Update: Scotch...

Posted on Sunday, March 10, 2019 at 8:00 AM
Focus Area Tags: Agriculture Pest Management

What to do with those tough to control perennial weeds in established alfalfa?

AlfalfaWeeds

The old saying, “Everything's fine until it's not,” comes to mind when dealing with some tough to control perennial weeds in alfalfa production during the summertime. Such was the case for an alfalfa field in the Sacramento Valley, where weed control seemed good up until mid-summer, and...

Posted on Friday, August 17, 2018 at 3:54 PM
Tags: Alfalfa (36), herbicides (5), weeds (65)
Focus Area Tags: Agriculture Pest Management

Matt Forister: Melissa Blue Butterfly and Colonization of Alfalfa

UC Davis alumnus Matt Forister, McMinn Professor of Biology at the University of Nevada, Reno,  will present a seminar at UC Davis on Wednesday, April 25 on his work with understanding the colonization of alfalfa by the Melissa blue butterfly.

Want to learn more about the Melissa blue butterfly and its colonization of alfalfa? UC Davis alumnus Matt Forister, McMinn Professor of Biology at the University of Nevada, Reno (UNR), will return to UC Davis campus on Wednesday, April 25 to discuss the research he and his lab are accomplishing...

UC Davis alumnus Matt Forister, McMinn Professor of Biology at the University of Nevada, Reno,  will present a seminar at UC Davis on Wednesday, April 25 on his work with understanding the colonization of alfalfa by the Melissa blue butterfly.
UC Davis alumnus Matt Forister, McMinn Professor of Biology at the University of Nevada, Reno, will present a seminar at UC Davis on Wednesday, April 25 on his work with understanding the colonization of alfalfa by the Melissa blue butterfly.

UC Davis alumnus Matt Forister, McMinn Professor of Biology at the University of Nevada, Reno, will present a seminar at UC Davis on Wednesday, April 25 on his work with understanding the colonization of alfalfa by the Melissa blue butterfly.

The Melissa blue butterfly, either Lycaeides melissa or Plebejus melissa, basking on an alfalfa plant. (Photo by Matt Forister)
The Melissa blue butterfly, either Lycaeides melissa or Plebejus melissa, basking on an alfalfa plant. (Photo by Matt Forister)

The Melissa blue butterfly, either Lycaeides melissa or Plebejus melissa, basking on an alfalfa plant. (Photo by Matt Forister)

Mandarin drought tips featured in final video of drought series

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:

Drought strategies for alfalfa

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.”

Drought management for California almonds

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.”

Irrigating citrus with limited 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.”

UCCE advisor Ben Faber is featured in the CIWR video on drought strategies in California mandarin production.

For a complete list of drought tips, see http://ucanr.edu/drought-tips.

Posted on Friday, April 6, 2018 at 7:33 AM
Tags: alfalfa (36), almonds (68), Dan Putnum (1), David Doll (26)
Focus Area Tags: Agriculture

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