The 10th World Avocado Congress will take place April 2 – 5, 2023 in Auckland, New Zealand. The event will bring together industry members from across the globe and include field day sessions, as well as in-person academic sessions. Those sessions will cover the following topics:
To maximize profits in the early navel orange market, growers need to have large fruit size and sufficient yellow-orange color and a high enough sugar-acid ratio to meet or exceed the legal minimum harvesting standards. Growers of early-maturing navel oranges in Kern County use different strategies to produce these oranges. Some growers irrigate at full evapotranspiration rates nearly up to harvest with the belief this will maximize fruit size, while others begin deficit irrigating a month or two prior to harvest to maximize development of sugar and color to promote earlier maturity. Little information exists in the literature to assist growers in making decisions related to producing early maturing navels such as Beck, Fukumoto and Thompson Improved. To determine the effects of late season irrigation stress, I, along with two University of California co-researchers Blake Sanden and Dr. Mary Lu Arpaia, participated in an experiment to elucidate some of the trade-offs that relate to irrigation strategies and early navel fruit production. The research was conducted from 2006 through 2008 in a cooperating grower’s Beck orchard at the extreme southern end of the San Joaquin Valley. Our generous and patient cooperating growers were George and Colby Fry.
Three different irrigation treatments, defined as low, mid and high, were developed based on the relative amounts of irrigation water applied to the test plots. Each plot consisted of 10 trees in a central row, bordered by ten similarly irrigated trees in the two adjacent rows. Each treatment was replicated five times. The same irrigation treatment was applied to the same plots for the first two years, while in the third year the low treatment was changed to the high treatment to provide information on how rapidly the trees would recover from stress. The different irrigation treatments were administered by using irrigation emitters with different flow rates and by differentially shutting off water to some treatments as needed to achieve desired stress levels. Between growing seasons, the top three feet of soil profile was refilled with water during the winter and differential irrigation began in early August. Measurable differences in tree shaded stem water potential among treatment usually were noted by early September. In the second year of the experiment (2007), the low and mid-irrigation treatments applied approximately 38 and 71 percent, respectively on average, of the water of the high treatment. Water potential measurements made mid-day on shaded, interior leaves demonstrated that good separation was achieved among the three differential treatments. In 2007, for example, shaded stem water potential measurement in early September were about -9, -12, and -18 bars for the high, mid and low irrigation treatments, respectively and at harvest in mid-October were -12, -18, -24, respectively. Neutron probe measurements also demonstrated that trees differentially depleted available water stored in the soil as the season progressed (data not shown). In 2007, differences in applied water among the treatments were large. Including the increased quantity of water applied to refill the soil profile in the winter, 3.55, 2.58 and 2.11 acre feet of water on a per acre basis, were applied to the high, mid and low irrigation treatments respectively, from October 30, 2006, to harvest, October 15, 2007. Rainfall was minimal.
Again, using 2007 as an example, as the level of applied water decreased, soluble solids (i.e. sugars) and titratable acid, were greater at harvest, although the sugar acid ratio was not different (see Table 1).
Rows in the experimental orchard were oriented east and west. Fruit on the south side of the tree had higher soluble solids concentration and sugar/acid ratio than fruit on the north side of the tree, regardless of irrigation treatment. Fruit juiciness, either measured as weight of juice to weight of fruit (see Table 1) or volume of juice per weight of fruit (results not shown) were not different among irrigation treatments, suggesting the increase in sugars and acid was the result of osmotic adjustment and not fruit dehydration. We were also interested in seeing if the differential irrigation treatments influenced eating quality of the fruit. To test this idea, we provided fruit from the highest and lowest irrigation treatments of 2007 and 2008 to volunteer panelists at the UC Kearney Ag Center and asked if they could detect any differences between the fruit. Results from both years showed that the panelists could not detect differences between the two irrigation treatments. This suggests that the increase in soluble solids in the low irrigation treatment was not sufficient to influence eating quality.
In 2007, yield and grade decreased as the amount of applied water decreased (see Table 2).
Fruit in the high and mid irrigation treatments peaked on size 56 per carton and on size 72 per carton in low treatment (data not shown). The decrease in fruit grade at pack-out appeared to be largely due to a more oblong shape. The negative yield, fruit size and grade effects measured in the low and mid treatments in 2007 were probably the cumulative result of deficit irrigation in Years 1 and 2 and not just Year 2 alone. Reduced rates of irrigation hastened development of fruit color compared to the high irrigation treatment (see Table 3) and this occurred every year.
The deleterious effects on yield, and grade on the trees in the low-irrigation treatments suggested that not much would be gained by continuing this level of stress for a third season in the same plots. In 2008, the low irrigation treatment was replaced by a high irrigation treatment and, at harvest, yield by weight and fruit numbers were not different from the control high-irrigation treatment. This observation demonstrated that the Beck navels rebounded quickly from the low irrigation stress of 2006 and 2007. The mid-level irrigation stress of 2006 and 2008 was less severe than that of 2007, and yield and fruit quality was not as adversely affected as in 2007.
This study provides information on some of the trade-offs that might be expected among fruit yield, size, grade, sugar and color in relation to reduced irrigation as harvest approaches. More detailed information from the trial can be found at the following link: https://doi.org/10.21273/HORTSCI.46.8.1163. How growers respond to this information will depend on their approach to profiting in the early navel market and how much water will be available for irrigation. If reducing water use is the primary goal of the grower, while minimizing effects on yield and fruit quality compared to fully irrigated orchards, work by Dr. Goldhamer, UC irrigation specialist, demonstrated that regulated deficit irrigation in the mid-May through mid-July time period would be the best strategy. The authors gratefully acknowledge the Citrus Research Board for its financial support of this project. — By Craig Kallsen, UC Cooperative Extension Farm Advisor, Subtropical Horticulture & Pistachio, Kern County
Following an extensive call for nominations, the Hass Avocado Board (HAB) named the recipients of its 20th Anniversary Recognition awards at the September Board Meeting and commemorated their service with a presentation and award recognition ceremony. The accolades acknowledge individuals for their outstanding commitment and achievements in “Making it Happen” for HAB by establishing and building the organization over the past two decades.
“Growing U.S. consumption of fresh avocados to more than 2 billion pounds per year since the establishment of the Hass Avocado Board in 2002 came thanks to the hard work of many talented, dedicated people from around the world,” said Salvador Dominguez, HAB Chairman. “Today, it is our honor to recognize several individuals for their prominent participation in our incredible success, for being relentless in their pursuit to “making it happen” for the benefit of the whole avocado industry in the United States.”
The criteria for recognition included having served the Hass Avocado Board as a board member, committee member, special subcommittee member, being affiliated with HAB, the California Avocado Commission (CAC) and the Importer Associations or being HAB staff.
After evaluating submissions, the 20th Anniversary Task Force of HAB , selected the following recipients:
The contributions from these individuals stand out on their own merit as well as underscore the HAB Effect, the ability for avocado industry members to accomplish things they would not be able to do without the collective power of HAB. By leveraging resources, expertise and passions strategically pulled together by HAB, Making it Happen Award recipients delivered strategic assets that propel growth such as world-class category data, industry-leading nutrition research and proven marketing campaigns.
Thirteen UC Davis scientists or former affiliates are among authors from eight countries who contributed to research articles for theJournal of Economic Entomology’sSpecial Collection: Research Advances in Spotted-WingDrosophila suzukii Management.
The recently published Special Collection showcases 14 articles.
Native to Asia, the agricultural pest is a worldwide threat to the berry production industry, which includes raspberries, blackberries, blueberries, strawberries, and cherries. The tiny insect, about 1/12 to 1/8 inch long, invaded the continental United States in 2008.
“All of the papers were by invitation of the co-editors of the special collection—Jana Lee,Cesar Rodrigue-Saona, and me,” said journal editor-in-chiefFrank Zalom, a UC Davis distinguished professor emeritus and recall professor in the Department of Entomology and Nematology. Zalom’s research includes the spotted-wing drosophila.
Lee, formerly with the UC Davis laboratory of the late chemical ecologist Steve Seybold, is a research entomologist with the Horticultural Crops Research Unit, U. S. Department of Agriculture, Agricultural Research Service, Corvallis. Rodriguez-Saona, who received his doctorate from UC Riverside, is an Extension entomologist with the Department of Entomology, Rutgers University, the State University of New Jersey.
In addition to Zalom and Lee, the UC Davis-linked authors include Joanna Chiu and Antoine Abrieux (Joanna Chiu lab); Zain Syed and Kevin Cloonan (Walter Leal lab); Gregory Loeb (Rick Karban lab); and Kelly Hamby, Hannah Burrack, Fatemeh Ganjisaffar, Brian Gress, Nicole Nicola and Mark Demkovich (Zalom lab).
Overall, the Special Collection includes authors from Austria, Brazil, Canada, Italy, Spain, Sweden, United Kingdom, and the United States that represent perspectives from universities, federal and state laboratories, growers, and pest product companies, according to the editors.
One paper, Spatio-temporal Variation of Spinosad Susceptibility in Drosophila suzukii (Diptera: Drosophilidae), a Three-year Study in California’s Monterey Bay Region, is from the Zalom lab and includes co-author, molecular geneticist and physiologist Joanna Chiu, professor and vice chair of the Department of Entomology and Nematology.
The work of molecular geneticist and physiologist Joanna Chiu, professor and vice chair of the UC Davis Department of Entomology and Nematology, is included in the Journal of Economic Entomology’s special collection targeting research on the spotted-wing drosophila. (Photo by Kathy Keatley Garvey)
UC Davis Department of Entomology and Nematology communication specialist Kathy Keatley Garvey provided the cover photo of the spotted-wing drosophila feeding on a raspberry.
Since 2008, “D. suzukii has become a key economical pest of raspberries, blackberries, blueberries, strawberries, and cherries in the United States and worldwide,” the editors wrote in theirintroductory remarks. “Not surprisingly, the number of publications has proliferated from 29 publications as of 2010 to 978 additional publications between 2011 and 2021 from a Web of Science search for ‘Drosophila suzukii.’ While many publications are available, this special collection will highlight advances in D. suzukii pest management since its U.S. invasion. We solicited papers by open call and received 66 abstracts, and selected 14 papers covering: 1) review, 2) monitoring and risk, 3) behavioral control, 4) biological control, 5) cultural control, and 6) chemical control.”
The collection is meant to serve “as a key reference point for entomologists across many institutions (e.g., academia, government, and industry) on important advances in D. suzukii pest management,” according to theEntomological Society of America. “The articles in this collection will also provide scientists information on potential research gaps that will help guide future research directions on this important pest. The goal is to preserve and catalog articles on various aspects of D. suzukii pest management, i.e., monitoring, cultural control, chemical control, behavioral control, and biological control, that will be shared among entomologists.”
USDA’s National Agricultural Statistics Service, Pacific Regional Field Office recently completed the California Mandarin Objective Measurement Survey. A sample of 293 Tango and W. Murcott Afourer Mandarin varieties were randomly selected proportional to county and variety bearing acreage. Results show an average fruit set of 596 fruit per tree and an average fruit size of 1.344 inches in diameter for these varieties. This compares with the 2021 average fruit set of 290 fruit per tree with an average fruit size of 1.363 inches in diameter and the 2020 average fruit per tree of 945 with an average fruit size of 1.488 inches in diameter. This survey was conducted for the first time in 2020.
Fruit counts were made from two trees per orchard, and fruit diameter measurements were taken on the right quadrant of four trees surrounding the two sampled trees.
The North American Raspberry & Blackberry Association (NARBA) will be gathering in person for their annual meeting to be held January 22-24, 2023, in Tampa, Florida. After two years of virtual conferences, the group will move the conference to the Sunshine State for the first time. The event will be held at the Hotel Alba Tampa. Visit the hotel website for more information on the hotel’s great amenities, including free wi-fi, outdoor pool, wellness center, and two in-house dining options as well as many walkable Tampa attractions and dining. Visit https://www.raspberryblackberry.com/2023-narba-conference/ for more information.
Conference sessions will feature top experts and experienced growers. Topics include caneberry breeding and varieties, pest and disease management, production research, new technology and industry updates, new grower resources, and marketing. Over 50 speakers from around the world are included in the multi-track format. Time for Q&A and networking will be part of all sessions.
Attendees will have the opportunity to register for the conference tour which will include field and nursery visits for an up-close look at the emerging raspberry and blackberry industry in Florida and a visit to the University of Florida Gulf Coast Research Center to learn about advances in berry research. The tour will include refreshments, networking with speakers and views of the beauty of the Florida Gulf Coast.
Registration for the conference, tour and the hotel block are OPEN NOW! A detailed listing of speakers and courses will be posted in October 2022 on https://www.raspberryblackberry.com/2023-narba-conference/ Early registration is recommended to ensure attendees have first choice for desired room types and sessions.
The North American Raspberry & Blackberry Association is a membership association of growers large and small, researchers, suppliers, and others in the caneberry industry.
For further information and updates about the 2023 NARBA annual conference please contact Darcy Kochis at info@raspberryblackberry.com.
The initial 2022-23 California Navel orange forecast is 76.0 million cartons, up 19% from the previous year, according to the USDA National Agricultural Statistics Service’s Objective Measurement Report. Of the total Navel orange forecast, 73.0 million cartons are estimated to be in the Central Valley. Cara Cara variety Navel orange production in the Central Valley is forecast at 8.0 million cartons. These forecasts are based on the results of the 2022- 23 Navel Orange Objective Measurement (O.M.) Survey, which was conducted from June 17 to September 1, 2022. Estimated fruit set per tree, fruit diameter, trees per acre, bearing acreage, and oranges per box were used in the statistical models estimating production.
This forecast includes production of conventional, organic, and specialty Navel oranges (including Cara Cara and Blood orange varieties).
Survey data indicated a fruit set per tree of 351, up 47% from the previous year and w e l l a b o v e the five-year average of 315. The average September 1 diameter was 2.106 inches, below the five-year average of 2.194 inches. The Cara Cara orange set was 307 with a diameter of 2.147 inches.
SURVEY SAMPLE
A sample of 785 Navel orange groves was randomly selected proportional to county and variety bearing acreage, and 717 of the groves were utilized in this survey. Once a grove was randomly chosen and grower permission was granted, two trees were randomly selected. The Navel orange sample included conventional, organic, Cara Cara, and Blood orange groves.
For each randomly selected tree, the trunk was measured along with all connected branches. A random number table was then used to select a branch, and then all connected branches from the randomly-selected branch were measured.
This process was repeated until a branch was reached with no significant limbs beyond this point. This randomly-selected branch, called the terminal branch, was then closely inspected to count all fruit connected to this branch, as well as all of the fruit along the path from the trunk to the terminal branch. Since each selected path has a probability of selection associated with t h e p a t h , a probability-based method was then applied to estimate a fruit count for the entire tree.
In the last week of the survey period, fruit diameter measurements were made on the right quadrant of four trees surrounding the two trees of every third grove. These measurements were used to estimate an average fruit diameter per tree. Of the 717 utilized groves, 8 were in Madera County, 109 were in Fresno County, 425 were in Tulare County, and 174 were in Kern County.
SURVEY HISTORY
A Navel Orange Objective Measurement Survey has been conducted in the Central Valley every year since the 1984-85 crop year, except for the 1991-92 season due to a lack of funding. The data from the first two years were used for research purposes in developing crop-estimating models. The Cara Cara forecast was undertaken at the request of the California Citrus Advisory Committee.
As citrus growers in the west dreadfully anticipate the arrival of the citrus killing disease Huanglongbing, researchers in the already severely impacted state of Florida are making significant strides in learning how to combat this disease.
Early results from a groundbreaking, large-scale citrus trial looking for solutions to the devastating citrus greening disease have given early hope for growers in the Indian River District. The new UF/IFAS research shows tree size does not seem to affect citrus susceptibility to greening.
In the trial, researchers are testing which citrus rootstock and scion combinations will tolerate citrus greening, a deadly global citrus disease that nearly decimated the Florida citrus industry.
Martin Zapien on one of the Millennium Block citrus cultivar trial planting days in 2019.
Martin Zapien, a graduate student at the University of Florida Institute of Food and Agricultural Sciences Indian River Research and Education Center (UF/IFAS-IRREC), presented data from the Millennium Block citrus cultivar trial in Fort Pierce, Florida. At his thesis defense, the information Zapien represented was research from a 20-acre grove with grapefruit, navel orange and mandarin cultivars on a wide range of newly released and commercial rootstocks. Planted in 2019, the trees grow in a region where citrus greening is now endemic.
Lorenzo Rossi, UF/IFAS plant root biologist and Tom James, a local citrus industry veteran, supervised Zapien’s research. Advisors on the project were UF/IFAS plant improvement team faculty Fred Gmitter, Jude Grosser and William Castle.
Nearly 80% of Florida’s grapefruit crop is produced by Indian River District growers, who export their crop to Europe and Asia. That’s why scientists study the fruit so closely, said Rossi.
“One of our objectives is to evaluate and compare the early performance of several new grapefruit hybrids grown on three commercial rootstocks under citrus greening conditions,” said Zapien.
In the first two years of growth, the researchers compared UF rootstocks and scions by measuring tree growth and the trees’ ability to tolerate citrus greening. They expect to collect yield and fruit data after the third year, Zapien said.
Rossi said data sets were specific to tree size, bacteria amount, the severity of citrus greening symptoms such as irregular yellow patches in the leaves, and leaf and soil nutrient concentrations.
“We have seen many rootstocks that promote large and small tree size, but we have not seen any correlation between tree size and susceptibility to citrus greening,” Zapien said.
But so far, the research does not support a theory that tree size affects citrus greening susceptibility, but there is a trend in small trees showing less citrus greening symptoms, Zapien said.
Zapien said published research findings prove that high-density plantings produce higher fruit yields by increasing yield efficiency — fruit number per green foliage. The researchers will evaluate if the trees correlate with the published work or if the larger trees in the test grove produce more fruit.
‘Ray Ruby’ grapefruit on UFR-15 rootstock promotes vigorous trees — the trees show the largest canopies and are already flowering. But for UF/IFAS researchers to recommend a particular rootstock and scion combination, more data are required. The experimental grove must be examined for up to four more years before UF/IFAS scientists can make reliable recommendations.
“All trees in the Millennium Block are infected with citrus greening. However, some trees are thriving,” Zapien said. “Trees on sour orange have shown significantly fewer disease symptoms than trees on x-639 and US-942 rootstocks, but we have to consider that sour orange’s drawback is the susceptibility to citrus tristeza virus.”
As to citrus greening severity, ‘Star Ruby’ grapefruit showed only 4% symptoms in the green foliage. In contrast, ‘US Seedless Surprise’ symptoms were 24%. The other varieties fall between the two.
“The data we compiled is nascent as the trees were only two years old at the analysis,” said Zapien. “University researchers will continue to monitor the top performer combinations to determine if the early findings are consistent.”
With research in the UF/IFAS-IRREC experimental grove, Zapien completed a master’s degree in horticultural sciences. Zapien recommends that researchers improve sampling methods to assess the bacteria as the trees mature to advance the research. Zapien and his colleagues will evaluate flowering patterns to determine when the fruit is ready to harvest and reveals market windows. A long-term goal is to measure the yield or the amount of marketable fruit each tree produces. — By Robin Koestoyo, University of Florida, Institute of Food & Agricultural Sciences
Citrus growers may have a new tool to help them slow the presence of citrus greening in already diseased trees. While there is no cure for Huanglongbing (HLB), researchers at the University of Florida Institute of Food and Agricultural Sciences found that injecting a benign Xylella fastidiosa EB92-1 bacteria biocontrol into infected citrus trees over a period of six years reduced the incidence of trees with severe HLB symptoms. The potential result is providing growers with a strategy to keep trees alive and productive longer even when infected with the citrus greening bacterium.
Donald Hopkins, an emeritus professor of plant pathology at the UF/IFAS Mid-Florida Research and Education Center, conducted three trials in central and eastern Florida with commercial groves of Valencia orange and Rios grapefruit trees at different maturity stages. All of the trees tested positive for citrus greening disease at the beginning of the trial but had varying ranges of symptoms from asymptomatic, mild to severe. Trees in the trials included young 2-year-old and mature (greater than 20-year-old) trees.
“Using EB92-1 provided a level of control of HLB in two mature citrus tree trials and in a trial initiated in young 2-year-old trees,” said Hopkins. “This biocontrol strain has the potential to prevent or delay severe symptoms of HLB and prevent the loss of production both in mature and young citrus trees.”
All trees in the trials remained positive for HLB throughout the six-year trial. The injections of EB92-1 did not prevent or reverse infection of HLB. But key findings indicated that trees that were treated had less increase in symptoms than untreated trees. Injected trees also had increased yield than untreated trees. In mature trees, results from the trials indicated that the most effective control of HLB may require once-a-year treatment for at least the first 2-3 years. Retreatment may be required yearly for best biocontrol.
Using EB92-1 especially combined with nutrition, fertilizer and pesticide best management practices could prolong the life and productivity of citrus trees.
Hopkins believes that the biological control of HLB by EB92-1 is not from direct competition with the HLB pathogen since the EB92-1 bacterium operates in a tree’s xylem and the HLB bacterium colonizes the tree’s phloem. Rather the impact in more likely an instance of induced resistance. Induced resistance occurs when a plant’s resistance mechanism is activated by infecting a plant with a pathogen, such as the benign strain EB92-1. In this case, injecting EB92-1 provided some control of HLB in a tree’s tissues not infected with EB92-1 resulting in a slowing of HLB symptoms.
This research was published online in Plant Disease, the journal of the American Phytopathological Society (APS). The project was partially funded by the United States Department of Agriculture HLB Multi-Agency Coordination (MAC) group and UF/IFAS. This treatment is patented and licensed to an external company but is not currently available to growers. The trials continue in central and eastern Florida. — By Ruth Borger, University of Florida, Institute of Food & Agricultural Sciences
Through support from the USDA Huanglongbing Multi-Agency Coordination Group (HLB-MAC) the Citrus Research Board (CRB) is initiating a California focused Citrus Research and Field Trials (CA-CRaFT) project. The overarching goal of CA-CRaFT is to demonstrate the effects of additional mitigations on Asian citrus psyllid control within commercial citrus groves across the various citrus growing regions in California. This project will measure psyllid levels within treated groves as a year-by-year measurement and relative to the regional psyllid levels. The additional mitigations are expected to help reduce psyllid populations and inform growers of best practices. The project results will be shared on a regional, statewide, and national basis.
To be considered for the program, growers should be actively following current UC IPM guidelines and interested in working with the CRB to test the effect of additional psyllid control methods
Producers may choose one or more of the following mitigations:
Preventative Mitigations
Barrier mesh fencing
Living windbreaks
Trap crops
Threshold-based Mitigations
Biological control agent releases
Pesticide treatments (border sprays, psyllid repellents, ant control)
Priority will be given to CA citrus groves with ongoing psyllid pressures and/or in proximity to major psyllid risk factors (i.e., transportation corridors, residential areas).
Compensation will be provided based on mitigations adopted.
Informational webinars will be held on September 8 and September 14, 2022. To learn more and register, please click on the respective links below.
Registration for the conference, tour and the hotel block are OPEN NOW! A detailed listing of speakers and courses will be posted in October 2022 on 
As citrus growers in the west dreadfully anticipate the arrival of the citrus killing disease Huanglongbing, researchers in the already severely impacted state of Florida are making significant strides in learning how to combat this disease.