- Author: Bradley Hanson
Several of us are part of a multi-state project on electrical weed control in organic blueberry and orchard crops. Tong Zhen is the lead grad student researcher on the UC Davis part of the project and we are working closely with our counterparts at Oregon State University (Marcelo Moretti and team) and Cornell University (Lynn Sosnoskie and team).
Tong wrote about our "first impressions" of the Zasso electrical weed control unit in 2022 and we included a demo of the equipment last year at the 2023 UC Weed Day. Tong's projects are just getting rolling for 2024 in blueberry, almond, and a new grower-led project with winegrape (more to come on those projects!).
Today, Luisa, the Oregon State University grad student on the project just posted a nice YouTube video of her electrical weed control research in organic blueberry in the Willamette Valley of Oregon. It's a nice walk-through of the research and has some good footage of the equipment in action. Here's the link to Marcelo and Luisa's video if you're interested: https://youtu.be/a_HHKVHeMjw?si=IKifjYX9M_ECTKrz
This research is funded by the National Institute of Food and Agriculture - Organic Research and Extension Initiative.
- Author: Michael Hsu
Anaerobic soil disinfestation helps suppress weeds, disease without fumigants
Troubled by puny plants, low yields and persistent mite problems, third-generation Southern California strawberry grower Glen Hasegawa was ready to give up on his transition from conventional to organic 12 years ago.
“I've always liked a challenge – but it turned out to be more of a challenge than I thought it would be!” he said.
But then, with the help of scientists including Oleg Daugovish, UC Cooperative Extension strawberry and vegetable crop advisor in Ventura County, Hasegawa tried a technique called anaerobic soil disinfestation (ASD). When applied correctly, the multi-step ASD process creates a soil environment that suppresses pathogens and weeds and makes for healthier, more robust crop growth.
“Back in the day, it was really hard to get the plant growing vigorously in organic,” said Hasegawa, owner of Faria Farms in Oxnard. “So we started using the ASD and then you could definitely see that the plant had more vigor and you could grow a bigger, better plant using it.”
Seeing that he could produce yields “in the neighborhood” of those grown in conventional strawberry fields fumigated with synthetic fumigants, Hasegawa was able to expand his original 10 acres of organic strawberries to 50 acres.
“I guess you could say I'm kind of a convert,” he said, noting that he now applies ASD to all his acreage each year in late spring.
Joji Muramoto, UC Cooperative Extension specialist in organic production based at UC Santa Cruz, has been experimenting with ASD since it was first brought to the U.S. from the Netherlands and Japan in the early 2000s. Carol Shennan, a professor in the Department of Environmental Studies at UCSC, and Muramoto were among the first to try the technique in California. They found that ASD successfully controlled an outbreak of Verticillium wilt – caused by the pathogen Verticillium dahliae – at UCSC's small organic farm in 2002.
Since then, Shennan, Muramoto, Daugovish and their colleagues have seen encouraging results at 10 trial sites across the state.
“We demonstrated that ASD can provide comparable yields with fumigants, in side-by-side replicated trials,” Muramoto said.
ASD promotes host of beneficial changes to soil ecosystem
ASD comprises three basic steps: incorporating a carbon source that is easily digestible by microbes in the soil (traditionally, rice bran has been used), further encouraging fermentation by covering the soil with plastic to limit oxygen supply, and finally adding water through drip irrigation to initiate the “anaerobic” decomposition of the carbon source and maintain the three-week “cooking” process.
The resulting cascade of chemical, microbiological and physical changes to the soil creates an ecosystem that is both conducive to strawberry growth – and inhospitable to pathogens and weeds.
“It's not like a pesticide where you have a mode of action, and thus resulting in ‘A' and ‘B' for you,” Daugovish explained. “There's a sort of cocktail of events that happens in the soil; they all happen interconnectedly.”
Compared to similar fields that did not undergo the process, ASD-applied organic strawberry fields across California have seen yields increase by 60% to 70% – and even doubling in some cases, according to Daugovish.
The UCCE advisor also shared the story of a longtime grower in Ventura County, who came to him with fields in “miserable” condition; they were plagued by one of the world's worst weeds, yellow nutsedge, and infected with charcoal rot, a disease caused by the fungus Macrophomina phaseolina. But after applying rice bran and following the ASD recipe, the grower saw phenomenal results.
“The only complaint he said to me was, ‘Now I have too many berries – we have to have more pickers to pick the berries!'” Daugovish recalled.
Via researchers' meetings, online resources, on-farm demonstration trials and word of mouth from peers, use of ASD by California strawberry growers has grown significantly during the past two decades. Tracking the purchase of rice bran, Muramoto estimated that about 2,500 acres were treated by the ASD-related practices in 2023 – covering roughly half of the 5,200 total acres of organic strawberries in California.
Muramoto directly links the growth of California organic strawberry production – which now comprises about 13% of total strawberry acreage in the state – with the increasing adoption of ASD.
“If you remove the acreage with the applied rice bran over the last 10 years or so, organic strawberry acreage is just flat,” he said.
Within the last decade, acreage of organic strawberries with ASD-related practices increased by 1,640 acres, which is a boon for air quality, human health and long-term soil vitality. According to Muramoto's calculations, that increase in organic acreage translates to a reduction of about 465,000 pounds of fumigant active ingredients that would have been used in growing conventional strawberries.
“There are hundreds of reports of acute illnesses related to fumigation in the record, so it's very important to find alternatives to fumigants,” said Muramoto, citing California Department of Pesticide Regulation documents.
Research continues to make ASD more economical, effective
The popularity of ASD has come at a price, however, for organic strawberry growers.
“There's more organic out there, and I think most of the organic guys are using it, so there's more demand on the rice bran; the price has been steadily going up every year, like everything else,” said Hasegawa, adding that he has been trying to decrease the amount of carbon while maintaining ASD's efficacy.
On top of greater demand from other growers and from beef cattle and dairy producers (who use rice bran as feed), the price also has increased due to higher costs in transporting the material across the state from the Sacramento Valley. So Daugovish and his colleagues – including Peter Henry, a U.S. Department of Agriculture plant pathologist – have been searching for a cheaper alternative.
“We all want an inexpensive, locally available, reliable, easy to use and functional carbon source, which sounds like a big wish list,” Daugovish said.
Carbon sources such as bark, wood chips, or compost are ineffective, as the crucial ASD microorganisms are choosy about their food.
“Microbes are just like cows; you can't feed them straight wood; they get pretty angry,” Daugovish explained. “And if you feed them something with too much nitrogen, they can't digest it – they get the runs. Microbes are the same way – you have to have the right proportion of stuff so they feel comfortable doing what they're doing.”
In search of an ideal replacement, researchers tried and ruled out grass clippings, onion waste, glycerin and coffee grounds. Finally, they pivoted to a material with properties very similar to rice bran: wheat bran, in the form of wheat middlings (also called midds, a byproduct of flour milling) and dried distillers' grain (DDG, a byproduct of ethanol extraction).
After field experiments in Santa Paula, the UC and USDA researchers found that midds and DDG were just as effective at controlling soilborne pathogens and weeds as rice brain – but at 25% to 30% less cost. Their results were published last year in the journal Agronomy.
“Not surprisingly, the wheat bran has worked almost exactly the same as rice bran,” Daugovish said.
He and Muramoto are now conducting trials with wheat bran at commercial fields, and the initial results are promising. Daugovish said the grower at one site in Ventura County has seen a 90% reduction in Macrophomina phaseolina, the causal pathogen of charcoal rot, in the soil – and an 80% to 90% drop in yellow nutsedge germination. They are waiting for final yield numbers after the coming summer.
While ASD has been beneficial to organic productivity and soil health, both Daugovish and Muramoto acknowledged specific limitations in suppressing the “big three” strawberry diseases: Verticillium wilt, Fusarium wilt and charcoal rot. In coastal areas with cooler soil temperatures, for example, ASD can actually exacerbate the latter two diseases, as the fungal pathogens feed on the rice bran.
“We know it works at warmer temperatures, but, practically, it's hard to do in coastal California,” Muramoto said. “It would be nice if we can find a way to suppress Fusarium wilt at a lower temperature, but we don't have it right now.”
That's why researchers emphasize that ASD is not a “silver bullet.” It's just one tool in the organic toolbox, which includes careful crop rotation, disease-resistant strawberry varieties and better diagnostic tests that help growers pinpoint outbreaks and make the application of various methods more targeted and more efficient.
And scientists will continue to optimize ASD to make it more effective and economical for growers in the different strawberry regions of California – from the Central Coast to the Oxnard Plain.
“We know it can work really well; it's just finding the most sustainable way to do this in our region,” Daugovish said. “We've got to just have an open mind and keep trying.”
/h3>/h3>/h3>- Author: Lauren Fordyce
If you've used disinfecting wipes to clean surfaces in your home, an herbicide to control weeds in your garden, or insect repellents while on a hike, then you have used a pesticide. A pesticide is any material (natural, organic, synthetic, or even homemade remedies) that is used to control, prevent, kill, or repel a pest. Pesticides are designed to be toxic against certain pests like weeds, insects, or bacteria. But when they are not used properly, pesticides can also be toxic to people and pets, and harm the environment including water quality, pollinators, and natural enemies.
February is National Pesticide Safety Education Month, a time to raise awareness about pesticide safety. Keeping yourself, your family, and the environment safe from pesticides starts with reading and understanding the pesticide label. Below are some key things to look for and follow on the label.
- Where can you use it? Some pesticides can be used on both edible and ornamental plants, indoors and outside. But other pesticides may explicitly state that they should not be used indoors, on edible plants, etc. Always be sure the label states that it can be used where you intend to use it.
- Signal words. The signal words Danger, Warning, or Caution on a pesticide label indicate the immediate (acute) toxicity of a single exposure of the pesticide to humans. Pesticides with the signal word Danger are the most toxic. Look for products with the signal word Caution, as these pose less risk of toxicity.
- What should you wear to protect yourself? When handling most pesticides, you should usually wear a long-sleeve shirt, pants, closed-toe shoes, eye protection, and chemical resistant gloves (not gardening gloves). This prevents you from being exposed to the pesticide through your skin, eyes, lungs, or mouth. For some other pesticides, like insect repellents you apply to your skin, read and follow the label for specific instructions.
- How long after applying can you enter the treated area? For many home-use pesticides, you can enter the treated area when the pesticide has dried. Entering an area where the pesticide is still wet can expose you to those chemicals. Some pesticide products may state that you must wait a certain number of hours before reentering the area.
- When can you harvest treated produce? If you applied a pesticide to your edible plants it's important to know when it is safe to harvest and consume them. Many pesticides can be applied to edible crops up until the day of harvest, but some pesticides may require days or weeks to pass before it is safe to do so.
- How should you store the pesticide? Pesticides should always be stored in their original container with the lid tightly sealed, in a locked storage cabinet where children cannot access them. Improper pesticide storage can lead to exposure incidents, such as a child drinking a pesticide or spilling it on yourself.
Following the pesticide label can prevent unintentional pesticide exposure to people and pets. To prevent harm to the environment, you should also follow these general guidelines:
- Don't apply pesticides in rainy or windy weather. If it is actively raining and windy, or rain is expected, hold off on applying the pesticide. Applying during rainy or windy weather can cause the pesticide to be washed away, polluting stormwater and waterways. It can also cause drift, which is when pesticide droplets or dust move through the air. Drift can harm nearby plants, bodies of water, or people.
- Don't spray plants in bloom. Protect pollinators and natural enemies (good bugs) that feed on pollen and nectar by not spraying flowering plants.
- Dispose of pesticides at your local household hazardous waste (HHW) site. Pesticide containers that are partially or entirely filled should be taken to a HHW site to prevent environmental contamination. Empty, rinsed pesticide containers can be disposed of in the garbage or recycled if accepted in your area.
Happy National Pesticide Safety Education Month. Visit Pest Notes: Pesticides: Safe and Effective Use in the Home and Landscape to learn more about pesticide use and safety.
- Author: Ben Faber
Practical Training in Nitrogen Planning & Management in Organic Production of Annual Crops
BUT All Growers Could Learn from these sessions
- Virtual Event – Habrá traducción al Español
3-part Workshop
Session 1: Monday, Nov. 27th, 2023, 1-3pm
Session 2: Monday, Dec. 4th, 2023, 1-3pm
Session 3: Monday, Dec. 11th, 2023, 1-3pm
Session 4*: Monday, Dec. 18th, 2023, 1-3pm
*attendance optional
Registration
tinyurl.com/NitrogenWorkshop
- Cost: $25*
*No one will be turned away due to lack of funds.
Please contact Rob Straser (rkstraser@ucanr.edu)
- Must enroll in Session 1-3 (Session 4 optional)
- Limited to 80 participants
- CEUs in progress
- CDFA-INMTP
- CCA
About this workshop
In this 3-part series, participants will learn how to estimate nitrogen release from diverse organic sources and translate that knowledge to nitrogen fertilization plans and regulatory reporting requirements. Over the 3 sessions, we will cover the most common sources of nitrogen and complete a nitrogen budget. In session 2 and 4, participants will be able to work on and receive feedback on their own nitrogen budgets.
Who should enroll?
Growers, CCAs, PCAs and other agricultural professionals who are interested in learning about nitrogen management in organic production are encouraged to enroll.
Program agenda
Session 1: Monday, Nov. 27, 2023, 1-3pm
Understanding nitrogen: the nutrient, the role of microbes and the
relevance of soil organic matter
Presenters: Daniel Geisseler, Radomir Schmidt and Margaret Lloyd
We will begin with an overview of the sources, transformations and fates of sources of organic nitrogen in soil. Foundational to this, we'll cover the role and dynamics of microbes in nitrogen management, and how that impacts management decisions. Lastly, we'll discuss using nitrogen budgets to understand the sources and proportions of available nitrogen to meet crop demand.
Session 2: Monday, Dec. 4, 2023, 1-3pm
Estimating nitrogen release from organic amendments and contributions
from cover crops
Presenters: Patricia Lazicki and Margaret Lloyd
This session will focus on estimating nitrogen release from compost, organic fertilizers and cover crops. In addition, participants will be invited to apply the training to their own operations and receive feedback on the budget calculations during this session.
2
Nitrogen Planning & Management Workshop UC Cooperative Extension
Session 3: Monday, Dec. 11, 2023, 1-3pm
Putting it all together: Completing a nitrogen budget, synchronizing
nitrogen release with nitrogen demand, soil tests, and frontiers in nitrogen
science
Presenters: Daniel Geisseler, Joji Muramoto, Michael Cahn and Margaret Lloyd
In this session, we will address specific aspects of organic soil fertility management in warm season vegetables. Discussions will include crop nitrogen demand and strategies to supply demand, as well as using and interpreting soil testing. Specific references will be made to strategies for complying with forthcoming regulations. We will conclude with a discussion on new frontiers in organic nitrogen management.
Session 4*: Monday, Dec. 18, 2023, 1-3pm
*attendance optional
Grower Panel and Open House
In this session we will have 1-2 growers share their experience managing nitrogen on their farms. Then, we will open it up to questions, share experiences and discuss the nitrogen budget file. Attendees are encouraged to bring their own data to receive feedback.
About the Presenters
Daniel Geisseler is a Cooperative Extension specialist in the Department of Land, Air and Water Resources at UC Davis.
Daniel's research and outreach focuses on nutrient turnover and plant nutrition in agricultural systems. He is interested in the
effects that different management practices have on nutrient use in California crops and how nutrient use efficiency can be
improved, particularly with nitrogen.
Patricia Lazicki is the Vegetable Crops Advisor for Yolo, Solano, and Sacramento Counties, working mainly in tomatoes.
Her research interests include soil health, and nutrient management and fertility in organic annual cropping systems.
Margaret Lloyd is the Organic Agriculture and Small Farms Advisor for Yolo, Solano and Sacramento Counties. She runs an
active research and outreach program focused on nutrient management and pest management for organic vegetable farms.
Joji Muramoto is an Assistant Cooperative Extension organic production specialist at UC Santa Cruz. His research and
extension focus on nitrogen and soilborne disease management in organic cropping systems across the state
.
Radomir Schmidt is a program manager at the Working Lands Innovation Center at the UC Davis Institute of the Environment.
As a soil microbiologist, Radomir conducts research on the effects of specific farming practices (organic amendment
application, enhanced rock weathering, cover cropping, no-till systems) on carbon sequestration and greenhouse gas fluxes in
soils, and on the roles of microbial communities in soil health improvement and maintenance
.
Michael Cahn is an irrigation and water resources Farm Advisor for UC Cooperative Extension in Monterey County. His
research and extension program focuses on irrigation efficiency, nutrient use of crops, and protecting water quality. He led
the development of CropManage, an online decision support tool for irrigation and nutrient management.
For more information, contact Rob Straser: (rkstraser@ucanr.edu) or Margaret Lloyd (530-564-8642, mglloyd@ucanr.edu).
The University of California prohibits discrimination or harassment of any person in any of its programs or activities. (Complete nondiscrimination policy statement
can be found at http://ucanr.org/sites/anrstaff/files/107734.doc). Inquiries regarding the University's equal employment opportunity policies may be directed to
Affirmative Action Contact and Title IX Officer, University of California, Agriculture and Natural Resources, 2801 2nd Street, Davis, CA 95618, (530) 750-1397
- Author: Trina Kleist
- Posted by: Gale Perez
A contraption with a long, low, green metal arm swept noisily along the edge of a row of almond trees in an experimental orchard just west of UC Davis. Little flashes of light sparked between the bottom of the arm and the green weeds below, and puffs of gray smoke wafted up from the stricken pests.
Electrical energy zooms through the plant down into the roots, and the heat damages cells. “We start seeing injury in the weeds within 30 to 60 minutes after the treatment,” said doctoral student Tong Zhen, of the Department of Plant Sciences. “Most weeds will be killed in a day.”
Two weeks after treatment during an orchard trial in May, all of the treated hairy fleabane was dead, and 70 percent of the field bindweed was toast.
In addition to evaluating the effectiveness of this electrical weed control device, the multistate team also is evaluating its effects on crop safety and on the tiny organisms living in the soil. “Maintaining soil health is an important goal of most organic producers,” Zhen added.
The weed-zapper was demonstrated during the 2023 Weed Day held June 21, and it's the focus of research by Tong, staff research associate Seth Watkins and principal investigator Brad Hanson, all in the Department of Plant Sciences. In addition to studying the zapper's effectiveness, they are looking at soil health and crop safety after repeated uses in both almond and blueberry fields that are managed organically. Colleagues at Oregon State University are testing the device in cherry orchards, and colleagues at Cornell University are testing it in apple orchards.
Machines with vision, herbicide tests and Google Street View
More research presented during Weed Day included:
- Efficacy and crop safety of fluridone in pomegranates. Postdoctoral scholar Rohith Vulchi and Brad Hanson, a professor of Cooperative Extension.
- Effect of endothall-treated irrigation water on almond orchards. Stephen Chang, master's degree student, and Brad Hanson.
- Machine-vision cultivators in processing tomato. Steve Fennimore, professor of Cooperative Extension in the department, and Scott Stoddard, UCCE Farm Advisor.
- Farm machinery sanitation to reduce the spread of broomrape seed. Postdoctoral scholar Pershang Hosseini and Brad Hanson.
- Chemigation strategies to manage broomrape in processing tomatoes. Doctoral student Matt Fatino and Brad Hanson.
- Orchard crop injury from simulated rice herbicide drift. Doctoral student Deniz Inci, Brad Hanson and Kassim Al-Khatib, the Melvin D. Androus Endowed Professor for Weed Science.
More research:
- Weed control efficacy and crop safety of the PPO-inhibiting herbicide tiafenacil in orchards. Recent master's degree graduate Guelta Laguerre and Brad Hanson.
- Using Google Street View to map weeds along road networks, making weed control more efficient. Mohsen Mesgaran, an assistant professor in the department, Tong Zhen and Kassim Al-Khatib.
- Using pendimethalin for water-seeded rice. Doctoral student Aaron Becerra-Alvarez and Kassim Al-Khatib.
- Evaluation of group 15 herbicides in tree nuts. Recent master's degree graduate Andres Contreras and Brad Hanson.
Learn more methods at Weed Science School 2023
An intensive, hands-on course offered Sept. 19-21 teaches how to identify weeds, apply herbicides safely and detect symptoms of herbicide problems. Lectures and discussions will cover weed biology, ecology, organic weed management, herbicide action and resistance management, resistance prevention and environmental impacts.
The school is designed for those involved in consulting, research, development or sales of agricultural chemicals in the private or public sector. It's offered through the University of California Weed Research and Information Center.
More about Weed Science School 2023 here.
Find schedule, cost and a full agenda here.
Related links
More about Tong Zhen's evaluation of the electrical weed control device is here.
UC Weed Research and Information Center has lots of resources for weed management.
Agenda for Weed Day 2023, listing additional research.
* * * * * * * * *
Original source: UC Davis • Dept. of Plant Sciences website • News: Sept. 5, 2023
Trina Kleist is the Communications Specialist for the Dept. of Plant Sciences at UC Davis. Her contact information is tkleist@ucdavis.edu, (530) 754-6148 or (530) 601-6846.