San Bernardino County HLB Quarantine Boundaries May Expand

CDFA Proposes Expansion of HLB Quarantine Boundaries for San Bernardino County

Effective January 6, 2020, the Department is expanding the San Bernardino County Quarantine Boundary. A map of the proposed boundary can be found at https://www.cdfa.ca.gov/plant/hlb/regulation.html#maps.

Regulated articles and conditions for intrastate movement under the quarantine can be found at Title 3 California Code of Regulations (CCR) section 3439. Pursuant to Title 3 CCR section 3439 any interested party or local entity may appeal a quarantine area designation.

Additionally effective January 6, 2020, the Department is expanding the ACP Bulk Citrus Regional Quarantine Zone 6 boundary in the San Bernardino County, Montclair area to mirror the recent expansion of the HLB quarantine area. A map of the proposed boundary can be found at: www.cdfa.ca.gov/plant/go/acp-quarantine#maps

Regulated articles and conditions for intrastate movement under the quarantine can be found at Title 3 California Code of Regulations (CCR) section 3435. Pursuant to Title 3 CCR section 3435, any interested party or local entity may appeal a quarantine area designation.

Process to Appeal the Proposed Expanded/Changed Boundary

The appeal must be submitted to the Department in writing and supported by clear and convincing evidence. The appeal must be filed no later than ten (10) working days from the date of this notification. During the pending of the appeal, the designated Quarantine Boundary under appeal shall remain in effect.

Mail Appeals to:

CDFA – Pest Exclusion

1220 N Street

Sacramento, CA 95814

California Ag Today2021-05-12T11:00:35-07:00January 6th, 2020|

Oriental Fruit Fly Quarantine Expands in Northern California

New Quarantine Measures 123 Square Miles

News Release Edited By Patrick Cavanaugh

A portion of Sacramento and Yolo Counties have been placed under quarantine for the Oriental fruit fly following the detection of 15 flies in and around the southern part of the City of Sacramento near the Lemon Hill community.

The quarantine zone measure 123 square miles, generally bordered on the north by El Camino Avenue; on the south by Laguna Boulevard, on the west by the Sacramento River; and on the east by Bradshaw Road. A link to the quarantine map may be found here: https://www.cdfa.ca.gov/plant/off/regulation.html.

To prevent the spread of Oriental fruit flies through homegrown fruits and vegetables, residents living in the quarantine area are urged not to move those items from their property. However, they may be consumed or processed (i.e. juiced, frozen, cooked, or ground in the garbage disposal) on the property where they were grown, or disposed of by double-bagging and placing in the regular trash bin, not green waste.

Following the principles of Integrated Pest Management (IPM), CDFA primarily uses the “male attractant” technique to eradicate this pest. Trained workers squirt a small patch of fly attractant mixed with a very small dose of pesticide approximately 10 feet off the ground on street trees and similar surfaces; male fruit flies are attracted to the mixture and perish after consuming it. This approach has successfully eliminated dozens of fruit fly infestations from California over the last several decades.

The Oriental fruit fly is known to target 230 different fruit, vegetable, and plant commodities. Damage occurs when the female fruit fly lays her eggs inside the fruit.

Small larvae generally enter the fruit at the stem end, although entry can be made anywhere on the fruit, particularly where two fruits touch. Larvae immediately bore to the center of the fruit and feed around the pit. After reaching maturity, they exit from the fruit and pupate.

While fruit flies and other invasive species that threaten California’s crops and natural environment are sometimes detected in agricultural areas, the vast majority are found in urban and suburban communities.

The most common pathway for these pests to enter the state is by “hitchhiking” in fruits and vegetables brought back illegally by travelers when they return from infested regions of the world or ship infested produce through the mail. Help protect California’s agricultural and natural resources; please Don’t Pack a Pest (www.dontpackapest.com) when traveling or mailing packages.

The Oriental fruit fly is widespread throughout much of the mainland of southern Asia and neighboring islands, including Sri Lanka and Taiwan, and it has invaded other areas, most notably Africa and Hawaii.

Residents with questions about the project may call CDFA’s Pest Hotline at 1-800-491-1899. Additional information may be found here: https://www.cdfa.ca.gov/plant/off/.

California Ag Today2021-05-12T11:01:53-07:00August 30th, 2018|

Huanglongbing Top Importance in Citrus

Huanglongbing Disease in Citrus is Top Problem

By Patrick Cavanaugh Farm News Director

Gary Schulz, President of the Citrus Research Board in Visalia, said the pest pressure in citrus comes down to three problems.

“You know, there’s three really. There’s Huanglongbing, Huanglongbing, and Huanglongbing, (HLB)” Schulz said at the recent California Citrus Conference in Visalia. “When I moved to California in 1990, I had an old-timer that was on my board. He said, ‘You know, in California, we have three major challenges: water, water, and water.’ Well, in the citrus research for pests and diseases, it’s really Huanglongbing.”

Gary Schulz

“If we’re talking about red scale or Phytophthora or lemon fruit drop, those are important challenges, but if HLB begins infecting our commercial groves and spreads as rapidly as it can without our attention and treatment or tree removal, the rest are moot,” Schulz said.

He discussed his hope for the future of the California citrus industry.

“I hope that in five years, we’ve solved HLB. That’s my personal goal. Somebody’s got to put the stake in the ground and put a date out there,” he noted.

Schulz said that Citrus Research Board has got a number of research programs that are all working side by side to find that solution, turn that key, and make that happen.

“It may be more than just one solution. We have a researcher at Washington State University in Pullman for example. They’ve earned a research grant from the USDA because of the creativity in putting their work team together and the fact that they bring a whole new fresh approach and fresh thought process to how to culture the bacteria that causes HLB disease. That’s huge in the science community and has never been done before,” Schulz said.

For more information go to http://citrusresearch.org/

California Ag Today2021-05-12T11:01:58-07:00October 17th, 2017|

Huanglongbing Discoveries in California

Recap of Huanglongbing Cases in California

News Release

Huanglongbing has now been confirmed in numerous communities in Los Angeles and Orange counties. These detections are disheartening, but the Citrus Pest & Disease Prevention Program, California Department of Food and Agriculture and county agricultural commissioners are taking aggressive steps to remove all diseased trees and educate homeowners about this critical threat to California citrus.

Here is a recap of the Huanglongbing activity in California to date:

Hacienda Heights:

HLB+ Trees = 2

HLB+ ACP = 1 (on the initial HLB detection site)

San Gabriel:

HLB+ Trees = 56

HLB+ ACP = 4 (on HLB+ tree sites)

Cerritos:

HLB+ Trees = 2

HLB+ ACP = 2 (1 on HLB+ tree site, 1 on a separate site)

Rosemead:

HLB+ Trees = 0

HLB+ ACP = 1

La Puente:

HLB+ Trees = 0

HLB+ ACP = 1

La Habra:

HLB+ Trees = 1

HLB+ ACP = 0

Anaheim:

HLB+ Trees = 11

HLB+ ACP = 8 (6 on HLB+ tree sites, 2 on separate sites)

Fullerton:

HLB+ Trees = HLB+ ACP = 1 (1 on HLB+ tree site)

In response to each and every HLB positive tree detection, CDFA conducts mandatory 800-meter response, which includes surveys and sampling of all host trees, treatments and removal of the confirmed HLB infected tree.

Nursery stock in quarantine areas is placed under USDA-approved screen facilities, where it is held and tested for two years, or it is destroyed. Outreach is done to homeowners and elected officials to educate them on the severity of the issue encourage them to help stop the spread of this devastating disease.

Patrick Cavanaugh2021-05-12T11:00:45-07:00June 26th, 2017|

Improved Huanglongbing Detection in Citrus Trees

Projects Underway for Better Huanglongbing Detection in Infected Trees

By Patrick Cavanaugh, Farm News Director

The big problem with Huanglongbing Disease (HLB), also known as citrus greening, is that an infected tree, despite having no visual symptoms, could quietly be a massive reservoir of HLB. The main vector, the Asian Citrus Psyllid (ACP), could easily pick up HLB from that tree and spread the disease throughout the orchard.

Currently, the main push to contain the possible spread of HLB is by controlling ACP. Yellow sticky traps are positioned near every commercial orchard in California, as well as near non-commercial trees in neighborhoods. Finding a psyllid on a trap triggers mandatory spray programs to help eliminate all psyllids in the area.

Neil McRoberts, associate professor of plant pathology, UC Davis

“Yes, one of the most critical questions in managing in HLB is the trees can be infected for a long time before you can visually see the ACP there,” said Neil McRoberts, an associate professor of plant pathology, University of California, Davis.

“There is a group of scientists, funded by the Citrus Research Board of California (CRB), working on different early detection methods. Those are methods where you would be able to tell the tree was infected before you could see the tree is infected,” said McRoberts.

The CRB funded field trials in Texas over the last few years that have narrowed the field of competitors to two or three techniques. The CRB will continue to fund the two leading contenders in that race to determine the leading early detection technology.

In the first technique, researchers analyzed all the microbes that live on a non-infected leaf surface and studied how that profile of microbes changes when the tree gets infected. Detecting a change in microbe profile could indicate the tree is not as healthy as it should be.

“Researchers take the microbes that live on an infected tree, extract the DNA from those microbes and run the DNA through a sequencer. The sequencer identifies which types of microbes are there,” he said.

McRoberts said sampling for microbes is easy. Researchers use an industrial-sized swab on the leaf surface. “You literally clean the leaf surface with the swab until it’s squeaky clean, put that swab in a bottle and send it to a lab. When it gets to the lab, they extract the DNA out of it and the rest of the process happens from there.

A female Tamarixia radiata laying egg on an ACP nymph. (Photo by J. Lotz). Courtesy of Citrus Research Board

In selecting which trees should undergo microbe swabbing, McRoberts noted that the ACPs tend to attack the groves from the outer edges, inwards. “At different times of the day, the light will be on different edges of the grove depending on where the sun is and how warm it is. You can target your sampling towards the places where you’re more likely to find it, but still, finding those initial little infections is tough.”

The second method is a technique called metabolic profiling. A newly infected tree starts to produce different proteins and other chemicals in response.

Still another research strategy is analyzing things that stay in the tissue. “There’s a change in the profile of metabolites in the tree. If you run those metabolites through a mass spectrometer, the mass spectrometer will spit out a profile. You can tell the difference between a healthy profile and an infected profile,” McRoberts said.

“This is how the dogs come into the picture. Everybody knows that citrus has an odor. When the trees are infected, the profile of the chemicals and the composition of that odor change. We can’t smell it, but a very sensitive electronic detector device can sometimes pick it up. Remarkably, dogs can pick it up. We think that’s what happening with the canine detectors; they’re picking up some change in the smell of the trees.”

McRoberts said that dogs are amazingly accurate in detecting trees with HLB disease. “The best that we can tell from the trials involving dogs, the false positive rate is less than 1 in 1,000. I’m very confident with the detector dogs,” McRoberts said.

Featured photo: Adult Asian citrus psyllid (Photo by J. Lewis). Courtesy of Citrus Research Board

Citrus Research Board of California (CRB)

UC Davis Department of Plant Pathology

California Ag Today2021-05-12T11:02:00-07:00December 2nd, 2016|

Gary Schulz Gives California Citrus ACP and HLB Update

California Citrus ACP and HLB Update from Gary Schulz

By Brian German, Associate Broadcaster

The Citrus Research Board (CRB) recently held their annual California Citrus Conference in Exeter, bringing together a variety of guest speakers and research presentations. The Conference focused on pressing Asian Citrus Psyllid (ACP) and Huanglongbing (HLB) issues, along with political action updates and current projects that are important to the citrus industry. Gary Schulz, president of the CRB, said “We have a 21-member board and we’ve been planning this event for the last 12 months. It’s been 4 years since we held the last conference,” noted Schulz.

Gary Schulz, president, Citrus Research Board

The CRB is responsible for overseeing the California Citrus Research Program (CCRP), a grower-funded and grower-directed program created in 1968 under the California Marketing Act. The CCRP’s purpose to enable California’s citrus producers to sponsor and support research that furthers the overall industry. Therefore, close to 70 percent of the CRB’s overall budget is allocated to research.

Schulz said the Conference “was a great, great day to have a good update on some of the dollars the Citrus Research Board has been spending on the growers’ behalf on research.” Schulz explained HLB represents the single greatest threat that citrus growers have faced worldwide.

For the past seven years, the USDA and Congress have allocated between $10 and $12 million dollars annually for ACP and HLB research operations. Advocacy groups and other supportive ag organizations have contributed the difference to reach an annual ACP and HLB research budget of close to $90 million dollars a year. We fund a lot of UC Riverside and USDA agricultural research, service researchers, plus research at UC Davis and the University of Arizona,” Schulz noted.

Schulz, who has many years of experience in California agriculture, having served as general manager of the Raisin Administrative Committee and CEO of the California Raisin Marketing Board, stated that CRB has a great working relationship with California Citrus Mutual (CCM). “Joel Nelson and CCM have worked very hard with the packers to assess themselves, put together a private foundation, and work with the university,” Schulz said.

Featured Photo: Adult Asian Citrus Psyllid (Source: The Citrus Pest & Disease Prevention Program)

Resources

California Marketing Act

Citrus Research Board (CRB)

California Citrus Mutual

California Ag Today2021-05-12T11:05:44-07:00November 18th, 2016|

ACP Spread in Bakersfield Area, Ingenious Research Proceeds

Ingenious Research Effort to Fight ACP Spread with Natural Predators

By Joanne Lui, Associate Editor

Beth Grafton-Cardwell, Cooperative Extension specialist, University of California, Riverside Department of Entomology

As we have reported in-depth before on California Ag Today, the Asian Citrus Psyllid (ACP) is a tiny, mottled brown insect that poses an ever-increasing threat to the state’s robust citrus industry, as well as to residential citrus trees. The pest can spread a bacterium known as Huanglongbing (HLP) that is fatal to citrus trees. The disease has nearly shut down Florida’s citrus industry.

Beth Grafton-Cardwell, cooperative extension specialist in integrated pest management, UC Riverside Department of Entomology, explained the significance of the recent ACP spread to Bakersfield. “That is really problematic because it’s mostly in the urban areas. It’s very difficult to find, to control and to stop that spread. It’s going to move out from that region into the local citrus orchards, and so there are lots of meetings and discussions right now to mobilize growers to get treatments to help protect their citrus orchards against the psyllid.”

#CitrusMatters

To contain the ACP problem, Grafton-Cardwell stated, “There are traps everywhere, but the traps are not terribly efficient. So, we really need to carefully examine groves and flush [new leaf growth] for the nymph form,” she said.

According to Agriculture and Natural Resources, University of California’s Statewide Integrated Pest Management Program:

Adults typically live one to two months. Females lay tiny yellow-orange almond-shaped eggs in the folds of the newly developing “feather flush” leaves of citrus. Each female can lay several hundred eggs during her lifespan.

ACP (Source: ACP UC IPM)

The eggs hatch into nymphs that are wingless, flattened, yellow or orange to brownish, and 1/100 to 1/14 inch long. Nymphs molt four times, increasing in size with each nymphal stage (instar), before maturing into adult psyllids. The nymphs can feed only on soft, young leaf tissue and are found on immature leaves and stems of flush growth on citrus.

The nymphs remove sap from plant tissue when they feed and excrete a large quantity of sugary liquid (honeydew). Each nymph also produces a waxy tubule from its rear end to help clear the sugary waste product away from its body. The tubule’s shape—a curly tube with a bulb at the end—is unique to the Asian citrus psyllid and can be used to identify the insect.

Grafton-Cardwell and other experts are concerned because once the ACP becomes established in urban areas, it is difficult to eradicate. “It starts spreading into the commercial citrus, and we’re off and running,” she commented.

In a ingenious effort to control the spread of the psyllid, trained teams of entomologists have imported Tamarixia radiata, a tiny wasp that naturally preys on ACP, from Pakistan to research and release in California. A cooperative effort of the University of California Riverside, Citrus Research Board, United States Department of Agriculture and California Department of Food and Agriculture, researchers are also exploring the effectiveness of another beneficial insect called Diaphorencyrtus aligarhensis to assist Tamarixia with control of the Asian citrus psyllid. To see where Tamarixia and Diaphorencyrtus have been released, visit this University of California’s website map at, “Distribution of ACP, HLB and Parasites in California,” and turn on the parasite layers.
Grafton-Cardwell said, “They’re going to inundate that area,” with natural ACP predators, “so hopefully that will push back a little bit.”

California Ag Today2021-05-12T11:05:46-07:00October 10th, 2016|

Breaking News: Cal Poly Opens New Greenhouse and Insect Rearing Facility

New Greenhouse Facility Opens to Save Citrus from Psyllids that Vector HLB

Facility to Rear Tamarixia Radiata, Natural ACP Predator

By Patrick Cavanaugh, Farm News Director

Scores of citrus industry leaders, citrus growers, scientists and CDFA officials attended the ribbon cutting event TODAY at the opening of a new greenhouse on the Cal Poly Pomona campus to rear Tamarixia radiata, a tiny parasitic wasp imported from Pakistan because it is an Asian Citrus Psyllid (ACP) nymph predator. ACP, in turn, is a serious nonnative citrus pest that can vector Huanglongbing (HLB)—a deadly citrus disease also known as Citrus Greening—that has devastated the powerhouse citrus

industry in Florida, threatens to ruin additional citrus economies, and is the biggest threat the California citrus industry has ever faced.

According to the United States Department of Agriculture Animal and Plant Health Inspection Service (USDA-APHIS), infected citrus trees “produce fruits that are green, misshapen and bitter, unsuitable for sale as fresh fruit or for juice. Most infected trees die within a few years.” ACPs have been detected in Alabama, American Samoa, Arizona, California, Florida, Georgia, Guam, Hawaii, Louisiana, Mississippi, Northern Mariana Islands, Puerto Rico, South Carolina, Texas and the U.S. Virgin Islands. Of those locations, the HLB disease has been detected in California, Florida, Georgia, Louisiana, Puerto Rico, South Carolina, Texas and the U.S. Virgin Islands.

ENTER: Tamarixia radiata

Use of the ACP predator, Tamarixia radiata as a biological control for ACP was discovered by Mark Hoddle, biological control specialist and principal investigator, UC Riverside ( UCR), Department of Entomology. The first release of Tamarixia was in December 2011 after USDA-APHIS cleared the natural enemy for release from the Quarantine Facility at UCR.

Mark Hoddle UC Riverside Department of Entomology

“Tamarixia can kill ACP nymphs in two different ways,” explained Nick Hill, a Tulare County citrus producer and Citrus Pest & Disease Prevention Program (CPDPC) chair. “The first is parasitism. In this instance, a female parasitoid lays an egg underneath a fourth or fifth instar—the larger and final developmental stage of the ACP nymph before becoming an adult—nymphs that are most preferred by Tamarixia for parasitism. When the egg hatches, the Tamarixia larva begins to feed on the under-surface of the ACP nymph. Eventually the larva completely excavates the body cavity of the ACP nymph and pupates inside the empty shell of its host.”

Hill explained the first releases of the tiny and harmless wasp will occur this fall in urban areas, “to help control ACP so that we do not have to do mitigations such as spraying in those areas. We hope to get to a point where we no longer need to go into people’s yards and ask if we can treat the trees.”

“The issue,” commented Valerie Melano, professor and chair, Cal Poly Pomona Plant Sciences and interim chair, Cal Poly Agribusiness & Food Industry Management/Agricultural Science, “is that we need to come up with the best possible ways to raise enough wasps for big releases to prey on ACP. We will have CDFA employees working in this green house, as well as student workers who have participated in our research program all along,” noted Melano.

Nick Hill, a Tulare County citrus producer and Citrus Pest & Disease Prevention Program (CPDPC) chair.

Hill added, “The idea is to get enough Tamarixia out there so they start reproducing themselves and they become self sufficient. This is tough to accomplish, but researchers think if they can get big numbers of the wasp into the urban areas, they can put a big dent in lowering the populations of ACP.”

Cal Poly Pomona Greenhouse

The new Cal Poly 5,040-square-foot research greenhouse, built in collaboration with Citrus Research Board and constructed through a $400,000 grant from the Citrus Pest & Disease Prevention Program, will house the second Tamarixia production program in California. CDFA’s Mount Roubideaux facility in Riverside houses current production. Both facilities will support the CPDPC biological control program that oversees releases in urban areas with high ACP populations.

The new greenhouse should produce a 1-1.5 million wasps. “It’s a very nice facility,” said Hill. “We are trying to boost the biological control program to produce four million Tamarixia a year.”

California Quarantine

The California Department of Food and Agriculture (CDFA) operates an extensive monitoring program to track the distribution of the insect and disease in both residential areas and commercial citrus groves. Results have determined quarantine zones, guided releases of biological control agents, and prioritized areas for a residential chemical control program. Nearly all of southern California is under quarantine for ACP, due to the fact that more than 15 residential trees have been discovered to be in infected with HLB.

The ACP quarantine in California includes parts of the following counties: Fresno, Kern, Kings, Madera, Monterey, San Benito, San Joaquin, San Luis Obispo, San Mateo, Santa Clara, and Stanislaus; and the following entire counties: Imperial, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, Tulare County, and Ventura.

Asian Citrus Psyllid Cooperative Program
California, Arizona, Baja California, and Sonora (USDA-APHIS). Visit our Citrus Diseases page to identify a plant infected by citrus greening, citrus canker, citrus black spot and sweet orange scab. If you detect an infected plant, report it immediately.

California Ag Today2021-05-12T11:05:51-07:00July 25th, 2016|

BREAKING NEWS: ACP QUARANTINES IN MERCED AND MONTEREY COUNTIES

ASIAN CITRUS PSYLLID (ACP) QUARANTINES IN MERCED AND MONTEREY COUNTIES

Quarantines are now in place in both Merced and Monterey Counties due to recent Asian citrus psyllid (ACP) detections. One ACP was detected near the City of Merced in Merced County and two ACP in one trap within the City of Salinas in Monterey County.

The quarantine zone in Merced County measures 123 square miles, bordered on the north by Kenney Avenue; on the south by W Dickenson Ferry Road; on the west by Shaffer Road; and on the east by

SAVE OUR CITRUS app is a free USDA iPhone to report and identify the four leading citrus diseases: citrus greening, citrus canker, citrus black spot and sweet orange scab. Report your symptoms, upload a photo and citrus experts will respond. ACP

E Yosemite Avenue. Monterey County’s quarantine measures 111 square miles and is bordered on the north by Pesante Road; on the south by the Salinas River; on the west by Castroville Road; and on the east by Gabilan Creek. The quarantine maps for both Merced and Monterey Counties are available online at: www.cdfa.ca.gov/go/acp-maps. Please check this link for future quarantine expansions in these counties, should they occur. Quarantines in new counties will be announced separately.

The quarantine prohibits the movement of citrus and curry leaf tree nursery stock, including all plant parts except fruit, out of the quarantine area and requires that all citrus fruit be cleaned of leaves and stems prior to moving out of the quarantine area. An exception may be made for nursery stock and budwood grown in USDA-approved structures which are designed to keep ACP and other insects out. Residents with backyard citrus trees in the quarantine area are asked not to transport or send citrus fruit or leaves, potted citrus trees, or curry leaves from the quarantine area.

ACP county-wide quarantines are now in place in Imperial, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, Tulare and Ventura Counties, with portions of Alameda, Fresno, Kern, Kings, Madera, Merced, Monterey, San Benito, San Francisco, San Joaquin, San Luis Obispo, San Mateo, Santa Clara, and Stanislaus counties also under quarantine.

The ACP is an invasive species of grave concern because it can carry the disease huanglongbing (HLB), also known as citrus greening. All citrus and closely related species, such as curry leaf trees, are susceptible hosts for both the insect and disease. There is no cure for HLB and once a tree becomes infected, the diseased tree will decline in health and produce bitter, misshaped fruit until it dies. In California, HLB has only been detected on residential properties in Los Angeles County. This plant disease does not affect human health.
Residents in the area who think they may have seen ACP or symptoms of HLB on their trees are urged to call CDFA’s Pest Hotline at 1-800-491-1899 or your local agricultural commissioner’s office (Merced County (209) 385-7431; Monterey County (831) 759-7325). For more information on the ACP and HLB, please visit: www.cdfa.ca.gov/go/acp.

California Ag Today2021-05-12T11:05:52-07:00July 14th, 2016|

Jasieniuk on Weed Evolution

Tracking Herbicide Resistance in Weed Evolution

By Emily McKay Johnson, Associate Editor

Marie Jasieniuk, professor and weed scientist at UC Davis College of Agricultural and Environmental Sciences, discussed her groundbreaking research, “I work on the population genetics and evolution of agricultural weeds and invasive plants,” she said. “We use molecular tools to look at the origins and spread of weeds. We also use molecular tools and genetic studies to understand the evolution of herbicide resistance in weeds,” Jasieniuk added, “to be able to propose management approaches that reduce the likelihood of further evolution and spread of resistant weeds.”

UC Davis Annual Weed Day 2016

Jasieniuk and her team identify the origins of invasive plants, and determine how they were introduced. “We study how they were introduced, how they have spread and whether they have been introduced multiple times. Again, if we understand how they’re spreading, we can do something to try to stop the spread,” she said.

Italian rye grass, a weed Jasieniuk is currently studying, is problematic because it is resistant to Roundup, a popularly used weed and grass killer by growers. “UC ANR Cooperative Extension specialist, now emeritus, Tom Lanini, and I sampled over 100 locations of Italian rye grass and tested them for resistance to Roundup ten years ago,” she said about the project, funded by USDA. “Last year, we re-sampled all of those sites, and we’re re-testing to see if there’s been an increase or a decrease or no change in resistance to glyphosate, to Roundup,” she said.

Roundup isn’t the only weed and grass killer available on the market. “We’re looking at resistance to three other herbicides,” she said. Working with growers to determine the most efficacious weed treatments that also reduce the likelihood of wood resistance to herbicides,” Jasieniuk explained, “We interview growers about their herbicide use, non-chemical approaches, and integrated management techniques to identify management practices that correlate highly with low or no resistance,” she explained.

Resistance management is found to be more effective with a rotation of various herbicides. “What you want to do is rotate different types of herbicides with different modes of action,” Jasieniuk said. “Perhaps do tank mixes and incorporate non-chemical approaches as well,” she added.

Eliminating weeds can be as simple as disking and digging them out with a shovel when there are only a few. “I think, in many cases, this would have done a lot to prevent new weeds from coming in and certainly resistant weeds from spreading,” she noted.

California Ag Today2021-05-12T11:05:53-07:00July 11th, 2016|