With two magnifying loops around her neck and a truck stocked with vials and tools for insect collection, Joanne O'Sullivan scouts Ventura County citrus orchards every day. She walks the perimeter, examining newly emerging leaves and tapping branches with a PVC wand to bat pests onto her clipboard.
O'Sullivan is one of four scouts hired and trained by UC Agriculture and Natural Resources scientists to carefully and continuously monitor citrus orchards for Asian citrus psyllid, an invasive pest in California that can spread the devastating huanglongbing disease.
In Florida, where the pest was left unchecked when it first invaded citrus growing regions, the disease swept through the state. Citrus production in the Sunshine State plummeted 60 percent in 15 years.
“We don't want to let that happen here,” said Beth Grafton-Cardwell, UC Cooperative Extension entomology specialist. Grafton-Cardwell hired O'Sullivan and her colleagues who monitor citrus in San Diego, Imperial, Riverside and San Bernardino counties to scour dozens of orchards to document how treatments to control ACP are working. Next year scouts will be added in Tulare and Kern counties.
When ACP are found, they are carefully bottled and sent to the lab to determine whether they carry the bacterium that causes huanglongbing disease.
The expansive ACP monitoring effort is funded by a $1.45 million multi-agency coordination grant from the USDA. The project funds promising tools and long-term solutions to reduce the spread of huanglongbing. Led by Neil McRoberts, a professor of plant pathology at UC Davis, the grant also provides funds for two other activities.
One is a collaboration with California Citrus Mutual to offer free citrus tree removal to homeowners in areas where HLB is known to occur. The second is modeling data from the CDFA HLB survey program, in which psyllids and symptomatic plant tissue are tested for the bacteria. Trees may have the disease but not show symptoms, so testing the psyllids is a more effective way to find infected trees. The modeling work will improve the ability to predict the locations of infected trees.
However, the main thrust is monitoring citrus treatments and their impacts on the ACP population with a team of scouts. A mix of conventional and organic farmers and growers who use biological integrated pest management programs to manage their orchards were recruited for the project. The farmers make ACP treatment decisions informed by research results that show the best treatments and timing.
“Most growers are coordinating their treatments to get a bigger bang for their buck,” Grafton-Cardwell said.
With just six months of data, the monitoring program has already yielded important information about Asian citrus psyllid.
“We're seeing more psyllids on the borders than the centers of groves,” Grafton-Cardwell said. “And so eventually, we will make recommendations that at certain times of year or when populations are low, the grower will only need to spray the borders of the grove."
This will reduce costs and the impact of pesticides on natural enemies.
"The early data have also revealed which chemicals are the most effective for psyllid control. We've found that organic growers need to be more aggressive in the frequency of treatments, because the organic insecticides are not as effective as conventional insecticides," she said.
At 8 of the 49 Ventura County ranches in the project, yellow sticky traps were placed in trees to monitor for ACP's natural enemies, including lady bugs, green lacewings, and Tamorixia radiata, tiny wasps from Pakistan that were released in California to battle ACP.
When O'Sullivan sees one of the natural enemies at work in the field, she pauses to observe the process.
“Sometimes I'll see a lacewing munching on an ACP and I'll say, ‘Go man, go!'” O'Sullivan said.
Planted in a corner of the UC Davis campus is a display of technologies and vegetable crops that researchers with the Horticulture Innovation Lab have been using with farmers in Africa, Asia and Central America. Led by UC ANR's Elizabeth Mitcham in the UC Davis Department of Plant Sciences, this program harnesses the agricultural expertise of a network of U.S. university researchers to improve how farmers in developing countries grow fruits and vegetables.
More often than not, the learning goes both ways: Adapting solutions for farmers on another continent can spark ideas that might be useful back home too.
So while the Horticulture Innovation Lab's Demonstration Center was built to showcase international work to campus visitors, you wouldn't be the first to wonder, “Would this technology work on a California farm too?”
Recently a team from UC Cooperative Extension in Fresno County — led by Ruth Dahlquist-Willard, UC Cooperative Extension advisor for small farms in Fresno and Tulare counties — worked with the Horticulture Innovation Lab to learn how to build one of these technologies, to try out with local farmers.
The low-cost technology they built, called a “chimney solar dryer,” combines continuous air flow with solar heat to dry fresh produce more efficiently than a traditional solar dryer. It was designed by the innovative duo Michael Reid and Jim Thompson, both emeritus specialists with UC Cooperative Extension who have worked on multiple inventions with the Horticulture Innovation Lab. The chimney solar dryer is usually built with basic materials, such as plywood, dark plastic, clear plastic, and food-grade mesh. Read more about how the chimney solar dryer can help farmers add value to crop surplus (PDF).
Here is a quick look at a couple of other technologies that visitors can see at the demonstration center:
This solar-powered cold room uses a tool designed by an American farmer, called a CoolBot. In a well-insulated room, a CoolBot can trick a household air conditioner into bringing temperatures down low enough for cool storage of fresh produce. Cooling fruits and vegetables soon after harvest from the field can reduce postharvest losses and extend shelf life. So far teams with the Horticulture Innovation Lab have used the CoolBot with farmers in Tanzania, Zambia, Uganda, Thailand, Cambodia, Bangladesh, India and Honduras.
The zero-energy cool chamber (known as ZECC) is a simple structure built from brick and sand that can help cool fresh produce, in conditions where evaporative cooling is effective. By regularly wetting the sand and brick, farmers or even marketers can keep the temperatures low and the humidity high for fresh produce such as leafy greens. Researchers with the Horticulture Innovation Lab have been testing what specific conditions — such as hot, arid climates with easy access to water — make this tool effective for farmers to use to cool their fresh fruits and vegetables.
More information about the ZECC is available from the UC Postharvest Technology Center.
Recent visits to the Horticulture Innovation Lab's demonstration center have come in many shapes and sizes — from people walking by who stopped to read some of the signs, to group activities planned in advance. Recent tours of the center have included a delegation of deans from agricultural colleges in Ethiopia, a television news crew from Tajikistan and high school students from California learning about innovation and human-centered design.
Maybe it will spark an innovative idea that you can use in your fields?
- More recent blog posts about the Horticulture Innovation Lab Demonstration Center
- Explore the African vegetables on display
- Learn more about the technologies on display
- Get updates from the Horticulture Innovation Lab's email newsletter
Led by UC Davis, the Horticulture Innovation Lab is funded by the U.S. Agency for International Development (USAID) as part of Feed the Future, the U.S. government's global hunger and food security initiative./h2>
For centuries, farmers have used all the colors of the rainbow to assess their orchards: The bright pink of blossoms in springtime, the vibrant green of heathy leaves, the red blush on fruit ready to harvest.
However, there are wavelengths beyond what a typical human eye can see that also provide valuable information about the crop – including tree vigor, plant stress, water use and fertilizer needs.
UC Cooperative Extension agricultural engineering advisor Ali Pourreza is peering into these previously invisible colorations to create a virtual orchard that will quickly, easily and inexpensively allow farmers and scientists to manage orchards for optimum production.
To develop his first virtual orchards, Pourreza launched a camera-equipped drone over an orchard at the UC Kearney Agricultural Research and Extension Center in Parlier. As the drone flies over the trees, it snaps thousands of photos and, using photogrammetry and software that stiches the images together, makes a three-dimensional point cloud model of the orchard.
A computer program can make colors that are invisible to the human eye – such as near infrared, red edge and ultraviolet – into imagery that illuminates key crop health indicators. Near infrared indicates the amount of healthy foliage, plant vigor and crop type. If the trees have low near infrared values, it means the plants are under stress. Red edge indicates plant stress and nitrogen content. High red edge values indicate nitrogen stress and low water content in plant tissues.
Patrick Brown, a pomology professor at UC Davis, is planning to use the virtual orchard to map nitrogen use in citrus.
“We are currently working on developing models to help growers determine their fertilization demands and have been contrasting the results from real orchards with the virtual orchard,” Brown said. “We have already utilized the approach to contrast the estimates of tree growth and yield with whole tree excavations and harvests to help validate the virtual approach and provide a more accurate estimate of tree nitrogen demand.”
Ultimately, Brown hopes to develop a way for growers to rapidly and cheaply estimate the nitrogen demand of their orchards, monitor the status of their orchards and manage nitrogen fertilizer applications.
In addition to the color variations brought to light by the virtual orchard, the system provides detailed data on other aspects of the crop development.
“We can learn canopy height and width, the spacing between the trees, total leaf area, canopy density and the amount of shaded area in the orchard,” Poureza said.
This data is of interest to scientists studying plant development, soil health and irrigation.
For example, UCCE agricultural water management specialist Daniele Zaccaria is researching the impact of soil-water salinity on water use by pistachio trees in the San Joaquin Valley.
“In our on-going research study we are characterizing the functional relationships between soil-water salinity, canopy size and density and evapotranspiration of pistachio trees through the light interception by the canopy,” Zaccaria said. “We plan to work with Ali to see how the virtual orchard approach can represent that and simulate the physical process of soil evaporation and tree transpiration as a result of different canopy sizes and densities intercepting different amounts of solar radiation.”
Zaccaria said he also plans to deploy a similar approach to understand how different canopy sizes, planting densities and row orientations found in commercial citrus orchards in the San Joaquin Valley – from navel oranges, to mandarins and lemons – can affect the citrus water demand and use.
In addition to the rich data that scientists can glean from the virtual technology, Pourreza envisions many applications of this technology for farmers, including yield forecasting, blossom mapping, variable pesticide application and robotic harvesting.
California citrus farmers have their ears perked for all news related to Asian citrus psyllid (ACP) and huanglongbing (HLB) disease, but the very latest advances have been available only in highly technical research journals, often by subscription only.
UC Cooperative Extension scientists are now translating the high science into readable summaries and posting them on a new website called Science for Citrus Health to inform farmers, the media and interested members of the public.
“The future of the California citrus depends on scientists finding a solution to this pest and disease before they destroy the industry,” said Beth Grafton-Cardwell, UC Cooperative Extension citrus entomology specialist. “Our farmers want to stay on top of all the efforts to stop this threat.”
Grafton-Cardwell and UC Cooperative Extension biotechnology specialist Peggy Lemaux are the two scientists behind the new website. When scientists make progress toward their goals, Grafton-Cardwell and Lemaux craft one-page summaries with graphics and pictures to provide readers with the basics.
For example, the website outlines scientific endeavors aimed at stopping the spread of huanglongbing disease by eliminating the psyllid's ability to transfer the bacterial infection. This section is titled NuPsyllid, and contains summaries of three research papers including one by UC Davis plant pathologist Bryce Falk.
Falk is collecting viruses found in Asian citrus psyllid; so far he has identified five. He is looking into the potential to utilize one of the viruses as is or modify one of the viruses to block the psyllid's ability to transmit the bacterium. For example, the virus might out compete the bacterium in the psyllid's body.
Another focus of the website is HLB early detection techniques (EDTs). If HLB-infected trees are found and destroyed before they show symptoms, ACP is less likely to spread the disease to other trees. EDT research described on the website includes efforts to detect subtle changes in the tree that take place soon after infection, such as alterations in the scents that waft from the tree (studied by UC Davis engineer Cristina Davis), changes in the proteins in the tree (studied by UC Davis food scientist Carolyn Slupsky) and starch accumulation in the leaves (studied by UC farm advisor Ali Pourreza).
As more research is published, more one-page descriptions will be added to the website. The website contains a feedback form to comment on the science and the summaries.
As 10-year-old Dominic Vargas crouched on the ground, in a cage not much larger than himself, trying to forage for tasty treats (candy) on the woodland floor...CRASH! The cage door came falling down and he realized that he had inadvertently tripped a tiny fishing line in his efforts to reach that candy - he was now trapped. Dominic seemed to accept his fate with good humor, shrugging, smiling and getting to work on that candy. Wildlife biologist, Jessie Roughgarden, commented that Dominic will now be collared, tagged and measured before returning him to the wild ... or in this case his parents.
This seemingly terrifying experience is in fact all part of the new "Sustainable You - 4-H Summer Camp" held at the UC Hopland Research and Extension Center. Sustainable You is a five-day camp allowing students to experience science and nature while learning about ways in which to conserve the land, water, air and energy.
View Dominic's experience in this 44-second video:
The camp is conducted at three of the UC Agriculture and Natural Resources' Research and Extension Centers across the state and each center tweaks the curriculum to suit their landscape and the kinds of research conducted at their sites. At Hopland this means getting the chance to meet with wildlife biologists from the UC Berkeley "Brashares Lab," led by professor Justin Brashares. It's an amazing opportunity for these kids to meet and ask questions of scientists conducting experiments in the countryside that surrounds them. Dominic may not be collared, but more than 10 deer on the property went through the same experience last week (minus the candy) as they were carefully captured by researchers and fitted with collars to better understand their movements and population across the 5,358-acre center.
The young team of scientists enjoying summer camp were also working to understand what wildlife shares the landscape with them by setting wildlife cameras daily and improving their positioning and locations each day. Advice from Brashares and Jessie Roughgarden helped the students improve their chance of catching footage of raccoons, foxes and maybe even a mountain lion. Day one produced fox video footage and shots of raccoons feeling around in the last pools of creek water to catch some of the tiny young frogs currently in residence.
Hear what Ahmae saw on her wildlife camera in the 59-second video below:
Exposure for these kids not only to hands-on activities exploring sustainability, but also to wildlife biologists, young researchers and professors working on today's wildlife and land management challenges, gives them an open door to explore their own future careers and interests.
As 9-year-old Ahmae Munday so sweetly put it, when asked what her favorite part of the Sustainable You Summer Camp was, "Everything! Especially the cameras."
The UC ANR network of Research and Extension Centers provide the perfect location to offer exposure to youth and communities to better understand and interact with the science going on in their own back yards and to inspire the next generation of researchers - as camp attendee and scholarship recipient Kaiden Stalnaker described in his scholarship application, "When I grow up I dream of a career in science and your camp would be a boost in the right direction."
Thanks to the researchers, camp counselors and students who have allowed the Sustainable You summer camp to inspire young people like Kaiden.