Posts Tagged: plant

Diagnosing herbicide problems takes detective work

Field day offers examples, tips for solving the mystery

A grower applies an herbicide to his tomato plants, or thinks a neighbor's treatment is drifting over her almond trees. A short time later, the leaves start to bleach or shrivel. Was it the herbicide? Or maybe water stress? Soil nutrients? Perhaps an insect?

Figuring out the causes of crop problems takes detective work, and like solving any mystery, it starts with knowing the signs, gathering evidence and asking questions.

The Diagnosing Herbicide Symptoms field day at UC Davis was an opportunity to see, up close, the shriveled cotton, scorched corn and dying sunflowers that can result when herbicides are applied incorrectly. Using the right herbicide – in the right proportion, at the right time and in the right field – can make the difference between a thriving crop and a financial loss.

A top take-away to avoid problems: “Don't do stuff at night!” laughed Becky Wheeler-Dykes, a UC Cooperative Extension farm advisor attending the June 26 event to better serve growers in Glenn, Tehama and Colusa counties. “The packages look the same. People grab the wrong jug.” And then, disaster.

Instructors were Brad Hanson, professor of Cooperative Extension; and Kassim Al-Khatib, the Melvin D. Androus endowed professor for weed science; both in the Department of Plant Sciences. They were joined by John Roncoroni, a Cooperative Extension emeritus farm advisor rooted in the department's weed science program. Attendees were a mixture of people from agriculture, industry, government officials, university researchers and Cooperative Extension advisors. The event was hosted by the Weed Research and Information Center, based in the Department of Plant Sciences.

Out in a field west of campus, visitors could see the progression of damage, from control plots with green and healthy crops to plants that looked sadder as herbicide concentrations increased. Visitors could see the patterns of damage for common foliar chemicals such as glyphosate, paraquat, and 2,4-D, as well as soil-applied herbicides from several chemical classes.

“There's a lot of detective work,” said Stephen Chang, a master's student in Hanson's lab aiming for a career in Cooperative Extension. “For example, the company that makes the herbicide says there shouldn't be a problem, but the grower says, there is a problem. This course helps with developing the skills to figure out what happened.”

It might not be the herbicide at all

Detective work and problem-solving frame the approach, Hanson explained. The cause of crop damage can be simple or complex. Like a good mystery, what appears to be a clue can turn out to be a red herring. Professionals need to draw on their inner Sherlock Holmes to observe and document symptoms, look for patterns in the plants and in the field, ask questions, gather information about the larger environment and collect samples.

An herbicidal Agatha Christie would then suggest: What if it's not herbicide damage at all? Participants learned to consider the possibility of insects, pathogens and viruses, as well as problems with water, nutrients, soil condition and even root damage from cultivation practices.

Hanson recalled puzzling over symptoms he found in an orchard. The culprit? “A leaking natural gas line,” he said.

More resources for herbicide issues

Participants also heard from Molly Mathews, deputy agriculture commissioner from Yolo County, on how a field investigation is conducted. Lawyer Robert Davies, of Donahue Davies LLP in Folsom, outlined the basics of what happens when there are lawsuits related to crop damage from herbicide drift.

The Diagnosing Herbicide Symptoms field day is part of a larger program of education and outreach offered through the Weed RIC, said director Julia Stover-Blackburn. It was the first time the event has been offered since the COVID-19 pandemic, she added.

• For more information about field days and resources, visit the Weed RIC webpage.
• For a thorough discussion of herbicide symptoms, visit this page overseen by Al-Khatib and sponsored by University of California Agriculture and Natural Resources.
• This online course follows an earlier version of the Diagnosing Herbicide Symptoms field program.

This story was originally published on the UC Davis Department of Plant Sciences website.

Blossom End Rot

This post is a rerun from 2023.

Have you noticed tomatoes that have round, water-soaked spots on the bottom? Blossom end rot (BER) is a frustrating problem that can be quite common in vegetable gardens, as it can affect tomatoes, peppers, and squash. You might notice it after a few very hot days. It usually starts on green fruit as a small, discolored spot on the end opposite the stem that might look water soaked. The spot enlarges and tissues dry out, becoming sunken, collapsed, and leathery.

Some tomato varieties, especially paste tomatoes, are affected more than others, but all varieties except cherry tomatoes seem to be susceptible if conditions are conducive. It is more likely to occur earlier in the season when plants are rapidly growing, but it can also show up later in the season when we have hot, dry weather.

Blossom end rot results from a low level of calcium in the fruit and a lack of water balance in the plant. Most of our soils have plenty of available calcium so there is no need to add more. Fluctuations in irrigation and/or heavy application of nitrogen are often the culprits in this condition. To reduce blossom end rot, monitor soil moisture to make sure the root zone neither dries out nor remains saturated. Follow recommended rates for vegetable fertilizers, using organic fertilizers.

Improvement in irrigation practices usually results in the problem going away. Rather than watering on a schedule, you should check the soil to determine its moisture level. Either by digging down into the soil without disturbing the roots or using a moisture meter, check to make sure the entire root zone is moist but not soggy. Use mulch around the plants to help maintain soil moisture, but make sure the mulch isn't right against the base of the plants.

Blossom end rot is not caused by a pathogen, so there are no pesticide solutions.

To reduce blossom-end rot:
• Use cover crops in the off season to increase water-holding organic matter in the soil.
• Irrigate before periods of hot weather.
• Don't disturb the root area.
• Don't over fertilize. Too much nitrogen during the early fruiting period can tie up calcium and make BER worse. Manure, especially poultry manure, can make it worse.

Vegetables affected by blossom end rot are still edible if they haven't begun to get moldy. Just cut away the discolored area.

More information about blossom end rot:
http://ipm.ucanr.edu/PMG/GARDEN/VEGES/ENVIRON/blossomendrot.html

Information about growing tomatoes in the home garden: https://anrcatalog.ucanr.edu/pdf/8159.pdf

 

Help Desk of the UC Master Gardeners of Contra Costa County (SEH)

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Second photo of blossom end rot

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Third photo of blossom end rot

Green Hall of Famer Oki retires after 29-year UC career

UCCE specialist's research prevents water pollution, reduces water use

When interviewed to become a University of California Cooperative Extension specialist in environmental horticulture, Lorence “Loren” Oki was asked what kind of research he wanted to conduct.

In response, he showed the hiring committee a photo of a residential gutter. “Water is a big concern, and I found very little research on runoff from homes,” said Oki, explaining that studying residential runoff is what “started his career” with UC Agriculture and Natural Resources back in 2002.

Although he remains active supporting growers and advising industry leaders, Oki retired from UC ANR in July 2023. Before joining ANR, Oki worked as a researcher for UC Davis' Department of Environmental Horticulture studying greenhouse irrigation in 1994, bringing his total time with the University of California to 29 years.

Oki, professor emeritus of Cooperative Extension at UC Davis, led many research projects that advanced the green industry which includes landscapes, nurseries and floriculture.

“Loren is the epitome of a specialist,” said Darren Haver, UC ANR's Research and Extension Center system director, who has worked with Oki for more than 20 years on projects that have  significantly improved urban water quality and water conservation efforts across California.

Research influences pesticide management statewide

With a $3 million grant funding a statewide study, Oki and Haver set out to characterize runoff from residential sources over a five-year period. They determined the volume of irrigation runoff from residential land use, as well as the pollutants in the runoff.

Oki and Haver, co-principal investigators, along with researchers from UC Davis and UC Riverside, discovered that the degradation products of the insecticide fipronil – commonly found in runoff water – were more toxic than its parent compound. The study led to an investigation of human pathogens and pathogen indicators in residential runoff, the first of its kind.

Another contribution was the early detection of a new pesticide used for ant control, enabling strategies to be put in place to prevent it from reaching local streams and creeks. Oki and Haver's work also persuaded the California Department of Pesticide Regulation to change pesticide labels to minimize the chances of pesticides moving off target during irrigation and rain events. 

These changes included preventing pesticide application before predicted rain and preventing irrigation after applications, keeping pesticides from impervious surfaces, and restricting applications on lawns and landscape beds within two feet of impervious surfaces and others.

Plant trials expand beyond California

Oki was also the principal investigator of the Climate-Ready Landscape Plants project, which may be the largest irrigation trial in the western U.S., and the UC Plant Landscape Irrigation Trials, the California component of that project. The UCPLIT trials originated in 2004 at UC Davis as a research project by Karrie Reid, retired UCCE environmental horticulture advisor for San Joaquin County, while she was pursuing her master's degree. In 2017, the irrigation trials were duplicated at the South Coast Research and Extension Center.

These projects evaluate landscape plants under varying irrigation levels to determine their optimal performance in regions requiring supplemental summer water. Throughout the trial, Oki identified many landscape plants, including rose cultivars, that remain aesthetically pleasing with little water.

Today, the trials have expanded beyond California as the Climate-Ready Landscape Plants Project at Oregon State University, University of Washington, University of Arizona and Utah State University.

Growing up in the nursery industry

In 2017, Oki obtained tenure, allowing him to expand his professional responsibilities to include production horticulture, specifically greenhouses and nurseries, an industry he was extremely familiar with. “I come from a nursery family,” Oki explained. “My grandfather started Oki Nursery in the early 1900s.”

During World War II, Oki's family was incarcerated in the Poston Relocation Center in Arizona and lost their homes and property. When they were released, they returned to the nursery industry to rebuild their lives. “After World War II, my father and uncle got more involved with my grandfather's work,” he said.

The Oki family played an instrumental role in technological development for nurseries in general. Oki Nursery, which was located in Sacramento, worked closely with IBM and was the first to use a computerized system in the industry.

Oki developed computerized scheduling for the bedding plants, poinsettias, chrysanthemums, bulbs and other crops.  He developed a method to calculate the cost of any crop grown by the nursery at any point in the crop cycle and computerized greenhouse environmental and irrigation controls. This may not sound impressive now, but that was in the 1980s.

“My father was known for being progressive and he also knew everyone at UC Davis,” said Oki. “He wanted to work with anyone who had an interest in doing something good for nurseries.”

Inducted into Green Industry Hall of Fame

In the 1950s, Oki Nursery partnered with researchers from UC Davis' agricultural engineering program and developed the overhead sprinklers commonly used in nurseries today. Until the 1980s, Oki Nursery was the largest nursery in Northern California. Before it shut down in 1993, Oki worked in the family business as a greenhouse manager when runoff became a growing concern.

“I remember getting served with a notice by the Regional Water Quality Control Board stating that we needed to prevent runoff because it was polluted with nitrate fertilizer, which was common in the nursery industry,” Oki said.

One of those efforts focused on using controlled-release fertilizer instead of applying fertilizer via irrigation as a liquid feed. “What we learned is that if we converted nurseries to controlled-release fertilizer, we could reduce the nitrate runoff,” he said. While a member of the Oki Lab, Bruno Pitton earned his Ph.D. studying nursery hydrology and the fate of nitrogen fertilizers in container crop production adding to the information on runoff and nitrate management. Pitton is now the environmental horticulture advisor for Placer and Nevada counties.  

In 2023, Oki was inducted into the Green Industry Hall of Fame, which recognizes individuals with a minimum of 20 years in the landscape, nursery or floriculture industry and who have made significant contributions to the field.

Having grown up in the industry, Oki said that his father taught him to never be afraid to try new things. “If you think you have an idea that might work, do the best you can to make it work. If it doesn't work out, then it doesn't work out. And that's OK,” he said.

Revitalizing space for greater impact

This mentality encouraged Oki whenever tackling new tasks, like rebranding the California Ornamental Research Federation, a space for education and collaboration, as UC Nursery and Floriculture Alliance.

In 2009, Oki and David Fujino, executive director of the California Center for Urban Horticulture, became co-directors of CORF, which catered to the cut flower industry. At that time, Oki and Fujino realized that nurseries generated much greater revenue in the state than cut flowers.

“It was a strategic decision to change CORF to UCNFA, which included floriculture and nurseries in the name,” Fujino said. Combined, nurseries and floriculture have consistently placed in the top five agricultural commodities in the state.

When reflecting on their partnership, Fujino said that working with Oki was a “natural fit.” “I couldn't have asked for a better partner, a better colleague and, ultimately, a better friend to have my back and work side by side,” he added.

Since UCNFA's launch, the two have worked to maintain the group's impact by hosting “Ask your Advisor” webinars to connect advisors to growers, as well as co-hosting large-scale events such as the annual conference for the International Plant Propagators' Society — an organization focused on greenhouse and nursery production education — for the Western Region, which Oki's father helped establish in the 1960s.

Encouraging a return to education

Gerry Spinelli, UC Cooperative Extension production horticulture advisor for San Diego County and member of UCNFA's administrative committee, described those who have learned from Oki as his sons and daughters. “When I meet someone that's learned from Loren or worked with him, that person instantly becomes my friend. That's the kind of effect Loren has on us,” Spinelli said.

Grant Johnson, UC Cooperative Extension urban agricultural technology advisor for Los Angeles and Orange counties, credits Oki for his master's degree in horticulture from UC Davis.

“Loren gave me a lot of direction as far as career choices and research interests. He instilled in me a dedication to life-long learning, just like he continues to do,” said Johnson. Before Oki became his professor, Johnson worked with Oki as a staff research associate at the South Coast Research and Extension Center in Irvine.

Another influential person in Oki's life is John Kabashima, emeritus environmental horticulture advisor for UCCE Orange and Los Angeles counties and fellow Green Hall of Fame inductee. Like Oki, Kabashima grew up in the nursery industry.

Oki, who earned a bachelor's degree in ornamental horticulture from Cal Poly San Luis Obispo and a master's degree in plant science from UC Riverside, decided to pursue a Ph.D. in ecology at UC Davis with Kabashima's encouragement.

While Oki was still working in his family's business, Kabashima said that Oki relied on UC ANR researchers for scientific information and felt like Oki wanted to be one of them. “I told him that he's a good nursery guy, but he's a better scientist,” said Kabashima. “His heart is in science.”

The two began working together as soon as Oki became a graduate student and have been colleagues and friends for nearly 40 years. “My favorite response from Loren whenever people ask him a question is, ‘It depends,'” Kabashima said. “It always leads to people opening up and giving more context. That's what Loren does, he gets you to think.”

Latest research in fire science focus of free webinar series

Wildfire, cultural and prescribed burns, plant flammability among topics covered

Interested in learning about some of the latest research in fire science and stewardship? Join the UC ANR Fire Network  for a series of free lunchtime webinars to explore fire science topics with colleagues from across the globe.

This four-part webinar series will address fire in land management, plant flammability, fire history and management and forestry and fuel profiles. 

Everyone is welcome to watch the Hot Topics in Fire Science and Stewardship Webinar Series. 

Restoring Fire to Meadows and Other Cultural Landscapes

Presenters: Alice Lincoln-Cook, California Indian Basketweavers Association; Brian Peterson, Fire Forward

• May 29, noon–12:45 p.m. Pacific Time
• Register by May 29: https://bit.ly/3Qksc0J 

How Can We Assess Plant Flammability?

Presenters: Jane Cawson, University of Melbourne; Max Moritz, UC Santa Barbara and UC ANR

• June 5, 3­–3:45 p.m. Pacific Time
• Register by June 4: https://bit.ly/3WetrlA

Nuances in Fire History and Management: Lessons from Oregon Presenters: Andrew Merschel, U.S. Forest Service Pacific Northwest; Chris Dunn, Oregon State University

• June 12, noon–12:45 p.m. Pacific Time
• Register by June 11: https://bit.ly/44fMU7u

Forestry and Fuel Profiles

Presenters: Don Radcliffe, University of Washington; Eric Knapp, U.S. Forest Service Pacific Southwest

• July 17, noon–12:45 p.m. Pacific Time
• Register by July 16: https://bit.ly/4aTqI5Q

For more information, visit https://ucanr.edu/sites/fire/Home_430/Events.  

 

 

How Plants Adapt to Their Environment

Next time you go for a walk in Upper Park, look closely at the different plants you see. Notice the enormous diversity of shapes, colors, and forms. There are trees, shrubs, perennials and annuals, all different shapes and sizes of leaves, and tremendous...

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