Posts Tagged: walnuts
The Community Alliance with Family Farmers and UC Cooperative Extension are working with farmers to establish six demonstration sites in walnut orchards that will examine the effectiveness of mating disruption to control two major pests of the crop – codling moth and navel orangeworm.
The three-year research effort is funded with a $1 million award from the California Department of Agriculture Biologically Integrated Farming Systems program.
“The project sites will be in the Sacramento and northern San Joaquin Valleys, but we expect the demonstration to be of interest to walnut farmers across the state,” said Sara Tiffany, CAFF director of ecological farming and the project lead. “Farmers who grow related crops, like almonds and pistachios, will also be able to benefit from the findings.”
“Farmers need alternatives. In this project, we will be studying the effectiveness of alternatives that already exist,” said Jhalendra Rijal, UC Cooperative Extension integrated pest management advisor for San Joaquin, Stanislaus and Merced counties, the lead scientist on the project. The California Walnut Board is also part of the project team.
Six farmers will be recruited to enroll at least 80 acres each in the demonstrations – three farmers in the Sacramento Valley and three in the northern San Joaquin Valley. The entire acreage will be managed following UC IPM guidelines for walnut production, including cover crops, reduced risk pesticide options and biological control.
Forty acres will be treated with commercially available mating disruption products, while the other 40 acres will not. The treatment works by confusing the pests. Codling moth and navel orangeworm moths naturally release pheromones that help them find mates. The female lays eggs in the immature nuts, and when they hatch, the larvae feed on the nuts, rendering them unmarketable. In the treated area, the orchards will be flooded with a synthetic pheromone that makes it much more difficult for male and female pests to hone in on one another.
Besides codling moth and navel orangeworm, the project will systematically look at the effects of cover crops and predatory mite release on pest mite populations, and improvement in other natural enemy populations in walnut orchards.
The results of the IPM practices will be shared widely with growers, pest control advisors and certified crop consultants in articles, meetings and field days.
“Currently the use of mating disruption in walnuts is significantly lower than in almonds,” said Rijal, who is also the associate director for Agricultural IPM with the UC Statewide IPM Program. “We believe when farmers see the results of using mating disruption, along with other sustainable walnut production practices, we will improve the adoption rate.”
Four staff research associates will join the ranks of UC Cooperative Extension scientists in the coming months to support nut crop advisors conducting critical research in walnut, almond and pistachio production.
The California Walnut Board, the Almond Board of California and the California Pistachio Research Board together have provided about $425,000 to cover annual salaries, benefits, travel and equipment for the new UC Cooperative Extension staff. Under the terms of the agreement, the new positions will be funded annually for up to three years, pending available funds and success of the program.
“By supporting these new positions in UC Cooperative Extension, the California Walnut Board, the Almond Board of California and the California Pistachio Research Board show their recognition for the value of applied research conducted by our nut crop advisors,” said UC Agriculture and Natural Resources vice president Glenda Humiston. “We are grateful to these industry organizations for this vote of confidence and the generous funding to generate science-based knowledge to apply on California farms.”
The new research associates will each devote time supporting two advisors with tree nut assignments:
- Allan Fulton and Luke Milliron, serving Butte, Glenn and Tehama counties
- Katherine Jarvis-Shean and Franz Niederholzer, serving Colusa, Sacramento, Solano, Sutter, Yolo counties
- Mae Culumber and Phoebe Gordon, serving Fresno, Madera and Merced counties
- Elizabeth Fichtner and an advisor under recruitment, serving Tulare and Kings counties
The arrangement reflects a change in how UC Cooperative Extension supports the agriculture industries in California with applied research. With less funding from its traditional revenue sources – USDA, the state government and counties – advisors cover more territory than in the past. Over the years, they have also taken on an increasing share of UC's applied research mission serving the state's specialty crops industries.
The new staff research associate positions were crafted to attract highly qualified candidates who will support advisors' applied research efforts. Their primary focus will be on assisting advisors with planning, execution and gathering data on experimental and demonstration field trials.
UCCE advisor emeritus Joe Grant, who now serves as production research director of the California Walnut Board, chaired an industry working group that drafted the plan based on advisors' input about their needs.
“Advisors are competent and creative people with the skills and knowledge to do research. They need the same support that researchers on campus have,” Grant said.
The California Pistachio Research Board previously provided funding for a plant pathology researcher and an integrated pest management advisor at the UC Kearney Agricultural Research and Extension Center in Parlier. In addition, the board supported creation of $1 million endowments for a nut genetics researcher and a tree nut soil science and plant-water relations researcher as part of an initiative co-funded by UC President Janet Napolitano.
“We've been concerned for a long time about UC Cooperative Extension's research capacity and infrastructure issues,” said Bob Klein, manager of the California Pistachio Research Board. “This new initiative will increase efficiency and productivity for farm advisors and also reduce their stress from being overcommitted.”
Josette Lewis, the Almond Board chief scientific officer, said the organization depends on UCCE farm advisors for unbiased, quality information about almond production.
“Advisors are a valuable link between UC campuses and growers, not only in doing applied research that helps growers thrive, but in meeting California's goals of environmental and social sustainability,” Lewis said. “The information they generate is shared with a host of ag industry professionals – pest control advisers, crop consultants and people in the private sector who provide services to growers.”
Commodity industry funding for UC Cooperative Extension reflects the value the nut crop industries leverage from one of the strongest agricultural research and extension systems in the world, Lewis said.
The new program is modeled after a pilot project in Colusa County in which the Almond Board provided funding for Niederholzer to hire an intern to support almond research. A young scientist who held the post from 2015-16 was Milliron. In 2017, UC Cooperative Extension named Milliron a sustainable orchard systems advisor for Butte, Glenn and Tehama counties and he will now supervise one of the new staff research associates.
“We had a chance to keep him in the system and capitalize on what he learned during his internship,” Lewis said.
There are other tree nut and fruit advisors in need of research help, Grant said. For example, there are concentrations of tree fruit and nut acreage and growers in Kern, San Joaquin and Stanislaus counties.
“We positioned these four research associates where we heard the need for help was most critical. We can see adding another position or two in the future if funds are available,” Grant said.
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)
When it comes to watering walnuts, most California growers believe you need to start early to keep trees healthy and productive throughout the long, hot summer. But according to striking results from a long-term experiment in a walnut orchard in Red Bluff, growers can improve crop production if they hold off irrigation until later in the season and directly measure their trees' water needs.
The findings from researchers at the University of California may help farmers optimize water use.
“It's a game-changer,” said walnut grower Hal Crain, who welcomed researchers on to his orchard to test irrigation optimization. “It's clear to me you can improve nut quality and yield by applying water based on what the tree wants and needs, rather than just watering when it's hot outside and the soil is dry. That's a big deal for walnut growers and for the entire agricultural industry.”
Changing the paradigm
Crain is a second-generation farmer whose family has been growing walnuts in Butte and Tehama counties for 55 years. Like most walnut farmers, Crain had always started irrigating in early to mid-May when the days grew warmer and the trees sprouted leaves.
“That's standard practice for probably 90 percent of California's walnut growers,” said Crain, walking amid his trees on a sunny afternoon. “The theory is that when you irrigate early, you preserve the deep moisture in the soil that trees need to survive the heat of summer.”
But that's not how it works, the research shows. Instead, trees that grow in saturated soil early in the season don't develop the deep roots they need to thrive.
“With all the water right there at the surface, the lower roots suffer,” explained Bruce Lampinen, UC Cooperative Extension orchard management specialist with the UC Davis Department of Plant Sciences. “Trees end up with a very shallow root system, which doesn't serve them well as they try to extract moisture from the soil later on.”
Lampinen has long suspected that walnuts were getting too much water in the spring.
“A lot of the symptoms we see like yellowing leaves and various diseases can all be explained by overwatering,” said Lampinen.
So Lampinen did what scientists do: He set up an experiment. Five years ago, with funding from the California Walnut Board and the U.S. Department of Agriculture, he joined forces with Ken Shackel, a plant sciences professor with UC Davis, and Allan Fulton, an irrigation adviser with UC Cooperative Extension. Together, they led a team of scientists testing irrigation on Crain's ranch.
“Hal is an exceptional partner,” Fulton said. “Farmers have a lot to accommodate when they host an experiment like this, with researchers going in and out of the orchard at all hours. He had to work around our people and the timing of our water treatments. He's always eager to experiment with technology and learn new things, and he shares what he learns with other growers. Hal completes the circle.”
Tough nut to crack
When is the best time to irrigate? Researchers say the trees hold the answer. Scientists use pressure chambers, which are air-pressure devices that measure a leaf or small shoot to gauge how hard the plant is working to pull moisture from the soil.
“Just because the soil looks dry doesn't mean the plant is suffering,” said Shackel, who specializes in plant physiology. “Pressure chambers let you ask the tree how it's feeling — sort of like taking a human's blood pressure — which is a much more accurate way to measure a plant's water needs.”
For the last five years, the team has been applying different water treatments to five blocks of trees. One block is getting standard, early irrigation. Crain's orchard managers begin irrigating the other blocks when the trees reach different levels of water stress based on pressure-chamber readings.
The trees that experience moderate stress are doing the best. Their irrigation usually starts in mid-to-late June, several weeks later than when standard watering begins.
“You can tell just by looking at that block that the trees are healthier,” said Crain, standing beneath a canopy of lush, green trees. “And, we're starting to see greater yields and better nut quality.”
Translating the research
The research is helping scientists advise farmers on irrigation.
“My biggest take-away is knowing when to start watering is a really important factor to the health of your trees,” Lampinen says.
Pressure chambers — sometimes called pressure bombs — can cost more than $3,000, and high-tech versions are under development.
“I tell growers a pressure bomb would pay for itself even if you just used it once a year to determine when to start watering,” Lampinen said.
Crain is certainly convinced.
“When you irrigate based on your trees' needs, you optimize water,” Crain says. “I'm not using less water overall, but the water I do use is producing more food. That's good news for everyone.”
This story was originally published in the Fall 2018 issue of Outlook Magazine, the alumni magazine for the UC Davis College of Agricultural and Environmental Sciences.
The UC Agricultural Issues Center has released a new study on the costs and returns to establish an orchard and produce walnuts in the northern San Joaquin Valley.
This study assumes a hypothetical farm size of 100 contiguous acres that is farmer owned and operated. Sixty acres are being established to walnuts and 35 acres are planted to other permanent or annual crops. The walnut orchard is planted on a 24-by-24-foot spacing using three-quarters inch caliber nursery grafted trees on a Paradox rootstock. The walnut trees are a late leafing, lateral bearing variety.
Input and reviews were provided by UC Cooperative Extension farm advisors and other agricultural associates. The authors describe the assumptions used to identify current costs for the walnut crop, material inputs, cash overhead, and non-cash overhead. Ranging analysis tables show net profits over a range of prices and yields. Other tables show the monthly cash costs, the costs and returns per acre, hourly equipment costs, and the whole farm annual equipment, investment and business overhead costs.
The new study is titled: "Sample Costs to Establish an Orchard and Produce Walnuts, in the San Joaquin Valley North – 2017"
This study and other sample cost of production studies for many commodities are available for download on the UC Davis Department of Agricultural and Resource Economics website at http://coststudies.ucdavis.edu.
For additional information or an explanation of the calculations used in the studies, contact Jeremy Murdock at the Agricultural Issues Center at (530) 752-4651, firstname.lastname@example.org, or UCCE advisors Joe Grant, email@example.com, David Doll, firstname.lastname@example.org, or Janet Caprile, email@example.com.