- Author: Alireza Pourreza
UC Digital Agriculture Program's innovative spray backstop system reduces airborne pesticide drift by 78% in almond orchards– a big step forward for improving air quality and working conditions in California's agricultural production areas.
The Issue
Pesticide drift is a significant concern, especially in California's almond orchards. It's not just an environmental issue. Pesticide drift can pose a public health risk by contaminating the skin, lungs, and gut of people in nearby communities. These chemicals can lead to respiratory issues, skin irritation, and other adverse health effects. Another study highlights that pesticide poisoning is a significant cause of morbidity and mortality, affecting not just agricultural workers but also the general population.The challenge has been to control this drift without reducing the effectiveness of the pesticide application. This project aims to tackle this pressing issue head-on.
How UC Delivers
Addressing the issue of pesticide drift requires a multi-disciplinary approach, combining engineering, agriculture, and environmental science expertise. The UC Digital Agriculture Program team rose to the challenge by developing an innovative spray backstop system. This system is a blend of practicality and advanced technology, designed to be both farmer-friendly and effective in reducing pesticide drift.
The core components of this system are a foldable mast and a shade structure. The mast is the backbone, providing the necessary height and stability, while the shade structure acts as a barrier covering the trees from the top. This barrier is crucial in preventing the upward movement of pesticide droplets, thereby reducing the potential for drift.
Figure 1: Schematic design of the backstop prototype installed on a sprayer in an almond orchard.
To validate the effectiveness of this system, a series of tests were conducted in young almond orchards. The sprayer was operated at a 3.2 km/h speed to simulate real-world conditions. But before hitting the field, the team employed advanced uncrewed aerial systems equipped with thermal and RGB cameras. These cameras captured images and videos of the spray pattern from multiple angles, providing invaluable data for analysis.
The aerial imagery was not just for show; it played a pivotal role in the project. It allowed the team to monitor the spray application in real-time and understand the spray cloud's movement pattern. This imagery was then used to refine the design of the shade structure, ensuring it effectively blocked droplet movement beyond the treetop.
Figure 2: Aerial views showing the efficiency of the backstop prototype in blocking the spray cloud.
The results were more than just promising. The backstop system effectively blocked the spray cloud, ensuring that the pesticides stayed precisely where they were intended to be—on the trees. This was further validated through a ribbon test, a simple yet effective method to measure drift. A ribbon placed in the spray path remained in its resting position when the backstop system was used, indicating a significant reduction in drift.
The project didn't stop at just reducing drift; it also ensured that the reduction did not come at the cost of effectiveness. The on-target deposition of the pesticide was not compromised, affirming that the system could achieve dual objectives: reducing drift while maintaining efficacy.
The Impact
The spray backstop system's impact goes beyond just numbers. It represents a significant stride toward sustainable agriculture and community well-being. The system successfully reduced the drift potential by 78%. This isn't merely a statistic; it's a tangible change that has far-reaching implications for both environmental stewardship and human safety.
Figure 3: Statistical results showcasing a significant reduction in drift potential.
The environmental impact is equally noteworthy. Reduced drift means fewer chemicals in the air, contributing to "improved air quality," a UC ANR condition change. This is a step forward in reducing air pollution, which has wide-ranging implications for human health and climate change.
One of the most noteworthy aspects of this innovation is that it managed to reduce drift without compromising the effectiveness of the pesticide application. The on-target deposition remained consistent, ensuring the almond trees received the necessary pesticide coverage for optimal growth and yield. This is a crucial factor for farmers who are often caught in the dilemma of choosing between effective pest control and environmental responsibility.
Figure 4: Comparative leaf samples illustrating consistent on-target deposition and coverage.
The project aligns with another UC ANR's condition change, "improved living and working conditions for California's food system and farm workers." One of the goals of reducing pesticide drift is to mitigate the health risks associated with working and living in agricultural production areas. Therefore, the work directly supports UC ANR's commitment to promoting the public health of California's communities.
Looking ahead, the project has set the stage for further research and development to adapt the system for different types of orchards and terrains. Additional modifications are being considered to make the system even more robust and versatile, ensuring its long-term sustainability and broader applicability.
Want to learn more? See the method in action here.
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In keeping with the Patrick Ranch Museum's mission to enhance “people's understanding and appreciation of our community's rich agricultural heritage,” a half-acre plot planted in heirloom almond varieties is situated between the Museum's entry road and the Master Gardener Demonstration Garden. Joseph Connell, along with Susan Donahue (both instrumental in establishing the Master Gardener Program in our county), were the masterminds behind the orchard. Real Dirt recently interviewed Connell about this tribute to the history of almond farming in Butte County.
Joseph Connell: Susan Donohue [retired UC Cooperative Extension Director in Butte County, and Patrick Ranch Museum Board Member] at Patrick Ranch expressed interest in featuring an historical almond orchard on the Ranch property. As the UCCE almond Farm Advisor, I agreed to work on the project with them. I used my contacts with almond growers and with the almond variety collection at UC Davis to locate budwood for each of the varieties. Budwood consists of short lengths of young branches with buds suitable for budding into a rootstock to create a tree of a particular variety. Nancy Fowler Johnson of Fowler Nursery (an orchard tree nursery in Newcastle, CA) agreed to support the project by propagating and donating enough trees of each of the varieties I included in the demonstration orchard.
RD: How and why did you choose the varieties you planted?
JC: I selected varieties that were most popular in the almond industry prior to 1900. Varieties planted here represent the foundational introduction period of the California almond industry from 1850 to 1900. Earliest plantings were of varieties such as Languedoc from the province of the same name in southern France. Languedoc originally produced poorly due to a lack of understanding of the need for cross pollination. The other varieties in this historical orchard were selected by early agricultural pioneers from amongst seedlings planted in California. They became the foundation of the California almond industry.
Nonpareil remains the leading variety in the California almond industry accounting for 39% of the total acreage in 2019. It is also the most valuable nut in dollars per pound returned to the grower. Breeders have been trying to match its quality for decades and haven't achieved that yet. The Peerless variety and a couple of others still have a small residual acreage in a few commercial orchards although improved varieties are widespread in today's orchards.
Specific varieties planted at Patrick Ranch, the year they were introduced into California production, and their original source include:
Row |
Variety |
Year Introduced |
Origin |
1 |
Ne Plus Ultra |
1879 |
A. T. Hatch, Suisun, CA |
2 |
I.X.L. |
1879 |
A. T. Hatch, Suisun, CA |
3 |
Peerless |
1895 |
Wilson Treat, Colusa, CA |
4 |
Nonpareil |
1879 |
A. T. Hatch, Suisun, CA |
5 |
Bidwell's Mammoth |
1881 |
Bidwell Ranch, Chico, CA |
6 |
Drake |
1880 |
H. C. Drake, Suisun, CA |
7 |
Languedoc |
1853 |
Languedoc Province, France |
Current statistics as of 2019: Nonpareil, the State's main variety, has 344,151 acres standing; Drake, 110 acres; Ne Plus Ultra, 1,647 acres; Peerless, (a few acres are still planted each year) 4,140 acres; while Bidwell, I.X.L., and Languedoc, are no longer listed by name in the 2019 Almond Acreage Report and may have passed into history.
JC: Trees were either available through the nursery directly, propagated by the nursery with budwood from the UC Davis collection, or in the case of the Bidwell variety, from a local grower, Randy Meline, who had maintained a tree of that Bidwell Ranch selection. I believe the nursery attempted to propagate ten trees of each variety. They delivered enough trees to plant the orchard with five trees of each variety. The eastern three rows were planted with four trees of each.
RD: Have all of the original trees survived?
JC: One Peerless tree on the south end of the row at Patrick Ranch died from gopher damage and a new Peerless tree was replanted several years ago on Lovell peach rootstock by Nick Bertagna [a third-generation Butte County farmer, as well as the retired UCCE 4-H Program Representative.]
RD: When were the trees planted? How far apart and why?
JC: Susan and I talked about moving the project forward in 2009. I located budwood, lined up the nursery as a cooperating partner, and the nursery propagated the trees in spring 2010. The trees were budded on ‘Hansen 536' peach/almond hybrid rootstock, which is the most drought tolerant of the currently available rootstocks. This rootstock has characteristics similar to the almond rootstock that would have been used prior to 1900. Bare root trees were dug from the nursery the following winter and, as a demonstration orchard, the one half-acre block was planted on February 21, 2011 to a single row of each variety. The early blooming varieties are planted mostly to the west of Nonpareil and the late blooming varieties are planted on the east end. Trees were planted in north-south rows so that visitors could walk along the north end of the rows and see each of the varieties. A relatively wide 25-foot square planting (70 trees/acre) was used since peach/almond hybrid rootstock will produce large trees similar to those on almond rootstock (current commercial orchards in the Sacramento valley are often planted at around 130 trees/acre on a peach/plum hybrid rootstock).
JC: As long as the orchard is harvested traditionally by knocking nuts off with poles, and not trunk-shaken mechanically, I would expect that it would have a lifetime of at least 30-40 years. It could be there even longer; for a long, long time was the Patrick Ranch's plan.
RD: What are the maintenance goals/requirements for these trees? Harvest goals?
JC: The first-year tree training was done by me and the early pruning/training and thinning of some crowded limbs was done by Nick Bertagna. Since it is not a commercial orchard, it is expected there will be minimal fertilization and spraying and not a lot of maintenance required.
The Patrick Ranch had hoped to be able to harvest some nuts and possibly sell them in their store or at public events as heirloom varieties. Unfortunately, the ground squirrels living happily in the adjacent oak grove have done most of the harvesting...at least, the last time I checked.
RD: What can we learn from this project?
JC: The half- acre orchard is mainly there to feature one of the early crops farmed in the Chico area and to preserve the heirloom varieties. Butte County was the number one county in almond production in the middle of the last century. It was the fourth largest county in almond production as recently as 1980. Now however, Butte County produces as many almonds as it ever did, but it currently accounts for only about 3% of the State's almond production due to the vast almond acreage expansion in the San Joaquin Valley.
RD: Will there be (have there been) maintenance, harvest, etc. demonstrations for the public?
JC: There have not been such demonstrations for the public to this point. A harvesting demonstration of how it used to be done using tarps, an almond maul, and bamboo poles could be held in conjunction with other events at harvest time.
Thanks to Connell, Donahue, and all the others involved in creating this living testament to the importance of the almond crop to Butte County's history and its current local economy.
UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system. To learn more about us and our upcoming events, and for help with gardening in our area, visit our website. If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu (preferred) or call (530) 538-7201.
- Author: Kathy Keatley Garvey
No thanks to the recent storms, almond orchards are encountering Nature's Extreme Makeover--from fluffy popcorn blossoms to tattered petals reminiscent of bottom-of-the-bag kernels.
Still, there's something spectacular about driving down a rural road in Dixon, Calif., and encountering rows and rows of almond trees.
Look a little closer and you'll see the bee hives. (It takes two hives per acre to pollinate California's 750,000 acres of almonds.)
Look a little closer and you'll catch a bee in the act of pollinating.
Today the cold temperature, plodding rain and incessant wind kept the bees clustered inside their hives.
![ALMOND ORCHARD in Dixon, Calif. shows rows and rows of popcornlike blossoms. (Photo by Kathy Keatley Garvey) ALMOND ORCHARD in Dixon, Calif. shows rows and rows of popcornlike blossoms. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/6285.jpg)
![BEE HIVES in a Dixon, Calif. orchard. (Photo by Kathy Keatley Garvey) BEE HIVES in a Dixon, Calif. orchard. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/6286.jpg)
![HONEY BEE pollinating an almond blossom. (Photo by Kathy Keatley Garvey) HONEY BEE pollinating an almond blossom. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/6287.jpg)
- Author: Kathy Keatley Garvey
Almond pollination season is approaching, and with it, come concerns.
"A concern each year...is how many honey bee visitation hours occurred during bloom," writes Extension Apiculturist Eric Mussen in his newly published edition of from the UC Apiaries.
Mussen, a former New Englander who has seen dozens of almond pollination seasons in California (he's been a member of the UC Davis Department of Entomology since 1976), says California now has approximately 710,000 acres of almonds. Each acre requires two hives for pollination.
Since California doesn't have that many bees, beekeepers from around the country truck in their colonies. The going rate per hive over the last several years has ranged from $100 to $150.
Generally, California's almond pollination season starts around Feb. 10, Mussen says, and ends around March 10. That takes into account the early, mid- or late varieties that bloom at different times. However, the pollination period for each individual orchard is around 10 days.
The flight hours of a honey bee during almond pollination season? Approximately nine hours a day over a 10-day bloom period.
And what are flight hours? Mussen defines "flight hours" as "the number of hours above 55 degrees when the wind is less than 15 miles per hour, given a sufficient level of sunlight without rainfall."
"I believe that if the tree varieties overlap well in bloom, the bees usually have moved the pollen around in the morning and early afternoon on good flight days," he writes in his newsletter. "That probably requires only about four hours a day."
Of course, poor weather can interfere significantly with "fertilization and nut set," Mussen says, "but it would not be the fault of the bees."
As a service to beekeepers and growers, a retired beekeeper posts information on the Almond Board of California Web site indicating who's renting colonies and who needs pollination.
Meanwhile, check out the images below of UC Davis bee breeder-geneticist Kim Fondrk in a Dixon, Calif. almond orchard. Fondrk manages the Honey Bee Pollen Hoarding Selection Program at the Harry H. Laidlaw Jr. Honey Bee Research Facility, UC Davis, under the direction of Robert E. Page Jr., Arizona State University. Fondrk and Page moved the bees from Arizona to California several years ago.
![BEE BREEDER-GENETICIST Kim Fondrk of UC Davis tends his bees in a Dixon, Calif. almond orchard. (Photo by Kathy Keatley Garvey) BEE BREEDER-GENETICIST Kim Fondrk of UC Davis tends his bees in a Dixon, Calif. almond orchard. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/3055.jpg)
![CLOSE-UP of Kim Fondrk of UC Davis in a Dixon, Calif. almond orchard. (Photo by Kathy Keatley Garvey) CLOSE-UP of Kim Fondrk of UC Davis in a Dixon, Calif. almond orchard. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/3056.jpg)
![HONEY BEE working an almond blossom. (Photo by Kathy Keatley Garvey) HONEY BEE working an almond blossom. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/3057.jpg)