Powdery mildew is an early season disease and growers should have a strategy in place as to how to manage it. Viticulture Farm Advisor Rhonda Smith talked about this at the recent Sonoma Grape Expo. Watch this interview with Rhonda as she offers some considerations for growers moving into the 2018 growing season.
Ithaca, New York, (April 2, 2018) – New clues to how the bacteria associated with citrus greening infect the only insect that carries them could lead to a way to block the microbes’ spread from tree to tree, according to a study in Infection and Immunity by Agricultural Research Service (ARS) and Boyce Thompson Institute (BTI) scientists.
Citrus greening, also known as “huanglongbing,” is a serious disease dramatically affecting citrus production across the world. Trees with this disease all die after only a few years. Citrus greening has been detected in every citrus-producing county in Florida, throughout the southern citrus growing states and in isolated spots in southern California. There is no effective prevention or cure.
The disease is associated with the bacterium Candidatus Liberibacter asiaticus, CLas for short, which is spread from tree to tree only by a tiny insect vector—the Asian citrus psyllid. If CLas cannot infect the psyllid, its ability to spread citrus greening is halted.
With the long-term goal of disrupting this CLas-Asian citrus psyllid interaction, research molecular biologist and BTI professor Michelle Heck, with the ARS Emerging Pests and Pathogens Research Laboratory, and BTI researcher Marina Mann focused on an important point: not all psyllids spread CLas equally well.
To be spread by the Asian citrus psyllid (ACP) effectively, the bacteria must pass through the cells lining the insect’s gut and multiply. Scientists in Heck’s lab had previously shown that the gut cells of adult ACP show severe stress responses when infected by CLas. The cell nuclei become fragmented, and some cells react to the point of dying, allowing the bacteria to move out of the psyllid and into the tree.
Now, the researchers have found that, unlike adult psyllids, young psyllid nymphs appear to be resistant to the effects of exposure to CLas, and their nuclei rarely reach the same level of disruption. This means CLas cannot enter psyllid gut cells to multiply.
The next step will be to identify the mechanism for this resistance in the nymphs so that it might be manipulated to also halt the spread of CLas by the adults. An important clue lies in how psyllid nymphs interact with symbiotic bacteria in their gut, especially Wolbachia pipientis.
Many insects are hosts for Wolbachia and often depend on these bacteria for important benefits—much like how human health depends on gut bacteria. In their study, Mann and Heck showed that in psyllid nymphs, Wolbachia and CLas are commonly found within the same cells.
The authors hypothesize that, in accommodating the beneficial bacteria, the nymphs also let in more CLas. This is supported by their finding that CLas levels in psyllid nymphs are strongly correlated with Wolbachia levels. Though this link remains to be tested directly, understanding its mechanism could yield an important target for disrupting CLas-psyllid interaction.
“CLas exploits the way nymph and adult psyllids differ in their guts to gain entry into its insect vector,” Heck said. “We may be able to use this new foothold in our understanding to develop ways to block transmission by insects in the citrus grove.”
If this works, “citrus growers will be in a much better situation in terms of disease control and saving the U.S. citrus industry,” said Dan Dreyer, Chairman of the California Citrus Research Board, which funds this and other research aimed at developing a management strategy for citrus greening.
“There are still many unanswered questions about CLas, how it is acquired and transmitted via the Asian citrus psyllid, and how it causes the disease,” continued Dreyer. “The more we learn about CLas and its vector, the closer we will get to moving citrus production past the threat of citrus greening.”
The Agricultural Research Service is the U.S. Department of Agriculture’s chief scientific in-house research agency. Daily, ARS focuses on solutions to agricultural problems affecting America. Each dollar invested in agricultural research results in $20 of economic impact.
What if you could have a pistachio variety that you could harvest earlier to reduce the chances of having Navel Orangeworm damage and concern for Aflatoxin levels? Well, the new early ‘Gumdrop’ pistachio is here. At the Annual American Pistachio Growers Conference, Bob Klein from the Pistachio Research Board talked about this new variety that is now available to growers on a small scale. Read more about it in Pacific Nut Producer Magazine.
With all the new tree nut orchards being planted in California, it’s important to remember that weed management is a priority, and it starts even before the planting process. Watch this brief interview with UCCE Farm Advisor Kurt Hembree as he explains, and read more in Pacific Nut Producer Magazine.
The recent early Spring freeze hit various Ag commodities all over the state, and the extent of the damage so far is unknown. Fortunately, most vineyards were still dormant at the time; however, some early white wine grapes, such as Chardonnay, had begun budbreak when the freeze hit. Watch this interview with Temecula grower JD Harkey, who shared how some of the vineyards fared. Read more in the April issue of American Vineyard Magazine, coming soon!
Modesto, Calif., (March 22, 2018) – In the next month, Almond Board of CA will host four “In the Orchard” workshops featuring Irrigation and Nitrogen Budgeting and Compliance. Hosted by the Almond Board of California, in conjunction with local irrigation companies, these workshops will provide an update on the Irrigated Lands Regulatory Program, a demo of automated and optimized irrigation infrastructure, and an overview of the California Almond Sustainability Program (CASP) online tools to assist growers’ increasing needs.
With the ever-changing regulatory environment, these topics are more timely than ever. Continuing Education Credits for Self-Certified Growers (from CURES) are being applied for. Beyond meeting with industry experts and learning the latest and greatest updates, this short, half-day workshop will allow you to learn about the tools being offered to help understand these hot topics.
Four workshops will be hosted in the almond-growing region on the following dates:
Lunch is complimentary. Call for location details.
Attendees can RSVP to, Rebecca Bailey, at rbailey@almondboard.com or 209-343-3245.
Davis, Calif., (March 22, 2018) – Monitor for rodent activity and use bait stations before the growing season to prevent problems, UC ANR scientists recommend.
Roof rats are running rampant in California orchards this year, according to UC Agriculture and Natural Resources scientists.
“In pistachio and other nut orchards, roof rats are burrowing and nesting in the ground where they’re chewing on irrigation lines, causing extensive damage,” said Rachael Long, UC Cooperative Extension advisor. “They are also nesting in citrus trees, feeding on the fruit and terrifying field workers when they jump out as people are picking fruit. The chewing pests are also girdling citrus limbs, causing branch dieback.”
The wet winter of 2017 led to lots of weed seeds for rats to eat. “Last season, rats were also nibbling on pomegranates, avocados, and other fruit and nut crops, rendering them unmarketable,” Long said.
Holes in the ground around the base of pistachio trees throughout a Yolo County orchard puzzled the grower.
“We looked for ground squirrels, but never saw any,” Long said. “We set up game cameras, but only got birds and rabbits. We put rodent bait in the holes, but the digging didn’t stop.”
Long, the pest detective, cracked the case by consulting Niamh Quinn, UC Cooperative Extension human-wildlife interactions advisor based in Irvine. “She informed us that the damage we were seeing was from roof rats.”
Burrowing roof rats sounds like an oxymoron. While roof rats generally don’t burrow in urban environments, their country cousins have been known to burrow.
“It’s not true that they don’t burrow,” Quinn said. “When I worked as staff research associate for Roger Baldwin, UC Cooperative Extension wildlife specialist, that is mostly what we studied, burrowing roof rats in orchards.”
Control measures – Baldwin said, “It seems to be a good year for rats in a number of different areas and crops throughout the state. I’ve received more questions and comments about rats this year than perhaps the last 10 years combined. As for bait application, putting bait down burrow systems for rats doesn’t usually work too well, so I’m not surprised that approach didn’t work. Growers will likely have better luck with bait stations in the trees.”
Because the rats climb, Baldwin suggests attaching bait stations to tree branches.
“In addition, elevating the bait stations will eliminate access to bait for many protected mammal species, such as kangaroo rats,” Long said. “The bait diphacinone grain can be purchased from some ag commissioners’ offices. This is what Roger Baldwin said they tested and it worked.”
As for the bait stations, they should be designed so that there isn’t any spillage for nontarget animals to eat, Long said.
When roof rat outbreaks occur, rodenticides are often needed to prevent crop damage. However, timing is critical as diphacinone use is highly restrictive and not allowed during the growing season, which is beginning as the weather warms.
“Check the product label for application instructions,” Long reminds growers. “It’s the law.”
Identifying the pest – One way for growers to identify whether they have roof rats is by the size of the burrows. The nocturnal pests are active above ground in trees and below ground.
“Roof rats can forage away from their nest, so you won’t likely find signs of their activity, such as rat droppings outside their burrow, to help identify them,” Long said.
Ground squirrels are active during the day, so they are more likely to be seen, dig holes about 4 inches in diameter and forage above ground near their burrows. Vole and mouse holes are 1- to 2-inches in diameter. Roof rat holes are typically 3 to 4 inches in diameter and might have nut shells in front of them, for example pistachio or almond shells. Rabbits will feed on seedling crops, but do not dig burrows.
Roof rats are prolific breeders that reproduce year-round, according to Baldwin. Females typically have three to five litters per year with five to eight young, enabling their populations to rapidly increase. The omnivores feed on a wide variety of plant and animal materials, allowing them to adapt to any environment, including urban and agricultural lands.
“Rats are sneaky and hard to spot,” Long said. “If you see damage, including digging in the soil but no wildlife, suspect rats.”
For more information on controlling roof rats, download Quinn and Baldwin’s free UC ANR publication 8513, Managing Roof Rats and Deer Mice in Nut and Fruit Orchards at http://anrcatalog.ucanr.edu/Details.aspx?itemNo=8513.
For more information about ground squirrels, download the free UC IPM Best Management Guidelines http://www.groundsquirrelbmp.com or UC IPM Pest Note http://ipm.ucanr.edu/PMG/PESTNOTES/pn7438.html.
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You can read the PDF version of the March Issue of California Fresh Fruit Magazine HERE!
Modesto, Calif., (March 20, 2018) – Big news this week: the judicial officer who was tasked with reviewing the entire California Federal Milk Marketing Order (FMMO) hearing record ratified it. This officially clears the way for USDA to release the final decision for a California FMMO. USDA did not mention how long it would take to release the final decision once the record has been ratified, but in theory, it could be any day now. After a disappointing delay, we are looking forward to the final decision. Making a choice to change or not to change a pricing system that has been in place for 50 years is not a decision many take lightly. To shed light on the implications, WUD will extensively discuss details of USDA’s decision at its annual Convention on March 28. More specifically, I will provide pricing and pooling scenarios and answer questions you may have. This is of course pending USDA’s decision. If for some reason it is further delayed, I will still provide information on the draft recommended decision. It is important to get information out, because once the final decision is released, the referendum process will start. That referendum period will only last between 30 and 45 days. This is a very short time frame to reach out to the producer community and explain all the details of this complex system.
As a reminder: the work of the judicial officer was required after a Supreme Court case called into question the appointments of administrative law judges (ALJ) in federal agencies. USDA announced last month the FMMO process for California could be significantly delayed until the court cases causing the delay were heard. This likely would have been around June. Hearing producers’ disappointment, USDA found a workaround and announced a solution during an industry conference call just weeks after the original delay announcement (appointing a judicial officer to review the FMMO hearing record). This officer is not subject to the appointment clause that applied to the ALJ that presided over the California FMMO hearing. Therefore, his review would prevent potential legal challenges down the road should the Supreme Court decide administrative law judges’ appointment was not constitutional.
By Annie AcMoody, director of economic analysis
Santa Rosa, Calif., (March 19, 2018) – In Sonoma County, our rich agriculture heritage is continually under attack from community members and elected officials who do not understand farming. There has never been more of a need for strong advocacy, education and communication on behalf of farmers. Sonoma County Farm Bureau’s board understands this and is making changes at Farm Bureau to provide leadership in defending and promoting local agriculture.
For the future of farming, the board believes that it is critical for Sonoma County Farm Bureau to refocus on its core mission of protecting agricultural lands, promoting agriculture and its products, educating the public and uniting in support of local agriculture.
Over the last year, we have been on a path to re-energize this mission. Starting with the grand opening of the new office and meeting space, Sonoma County Farm Bureau is becoming the go to place for ag groups to meet in support of local agriculture. This office space has been a vision of the board for the past few years and it is exciting to watch the space become a hub for conversations, meetings, workshops and even ag celebrations. And we are only getting started. More improvements are ahead that will support the collaboration of agriculture.
We have also been making leadership changes to our staff. I am happy to share that the board has offered the full time executive director position to our Interim Executive Director Tawny Tesconi. On March 1, Tawny assumes the full-time position. Over the last 75 days as interim director, she has done more for our mission than the progress we saw in the last couple of years.
Tawny’s extensive background includes being a Sonoma County native, growing up in agriculture, participating in 4-H and FFA as a kid and a 30-year career in fair management and public service. We are confident that she is the right leader at the right time for Sonoma County Farm Bureau.
Under Tawny’s leadership, we have hired a new executive assistant / office manager, Samantha Piehoff, and Tawny has also been working with the current staff to ensure operating efficiencies, deliver better service and offer more value to Farm Bureau members. We are excited to see how Sonoma County Farm Bureau will thrive under new leadership and clear direction.
Moving forward, we are fully committed to our mission and will stay focused on three key priorities:
With the Board of Directors’ and Tawny’s great leadership, I look forward to a stronger and much more relevant Sonoma County Farm Bureau in the near future.
Written By: Steve Dutton, President, Sonoma County Farm Bureau
