Determining Planting Density

 APRIL 15, 2024 ECONOMICS,  PLANTING

As growers grapple with planting new blocks in the HLB era, there has been considerable discussion about planting densities to optimize growth and yield. John Chater, assistant professor of horticultural sciences with the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), has been working with growers in evaluating new varieties and rootstocks as trees are planted.

TRENDING HIGHER

He says most growers are trending toward higher densities when compared to the historical standard. But he adds the trend toward pushing densities higher has plateaued for now. 

“There must be a sweet spot for density when considering cultivar selection, site conditions and cultural practices,” Chater says. “With HLB, there are often less fruit per tree, so it perhaps makes sense to have more trees per acre to maximize production. The nutrient requirements of plantings with higher densities need to be worked out, as do the water factors. How planting more trees per acre affects drought conditions (considering tree stress) and nutrient uptake in the field can be important factors to consider.”

However, one factor that could push tree densities much higher would be planting super-high-density groves to set them up for mechanical harvest. There are a few experimental groves in the state that are testing this concept; learn more.

ECONOMICS OF DENSITY

A UF/IFAS study in 2022 evaluated three planting densities and their economics. The study compared 145 trees per acre (25 x 12 feet), which is a historical average, to 220 trees (22 x 9 feet) and 303 trees (18 x 8 feet) per acre. The study considered cost factors like irrigation, frost protection, fertilization and other production expenses. And the study assumed that the lifespan of groves has been reduced from 30 years to 20 years due to HLB.

When factors were considered and tabulated, the study found that the statewide average density of 145 trees per acre was not profitable under current market conditions. Despite the higher upfront level of investment required for planting 220 and 303 trees per acre, the study showed that under the assumptions and scenarios analyzed, those investments yield positive returns.

The study found that while in a higher-density grove trees produce somewhat less yield compared to trees in a lower-density grove. The higher number of trees contributes to a higher yield per acre. Therefore, planting higher-density groves could help offset some of the impact of HLB by decreasing the cost of production per box due to costs being allocated to a higher number of boxes. This ultimately results in an increase in profitability per acre.

The study’s authors noted limitations of their analysis: “First, because HLB was first found in Florida in 2005, it is not yet clear how trees will be affected by the disease in the future. Therefore, in our model, the impact of HLB on yield of trees that are 13 years old and older is a projection based on current data. Second, we did not include any potential impact of weather events such as freezes or hurricanes (and their effect on prices and yield) in our analysis. Third, potential future management strategies or solutions to HLB could involve planting (new) trees with resistant or tolerant traits to the disease, which could make an existing grove with trees that do not have such traits obsolete.”

According to Chater, most growers have taken the economics of higher density to heart.

“More than 200 trees per acre seems to be the more common number for growers putting in new blocks most recently,” he concludes.

Read the full economic study here.

CRAFT Program Promotes New Planting and Knowledge

7 The CRAFT program is responsible for nearly 10,000 acres of citrus plantings, including new blocks and resets. Since its founding in 2019, the Citrus Research and Field Trial (CRAFT) program has been responsible for the planting of just under 10,000 acres of new trees. This includes about 6,000 acres of solid-set groves and just shy of 4,000 acres of resets. CRAFT is a first-of-its-kind program and considered an innovation among funding agencies needed to support such efforts. The program’s first director, Kristen Carlson, won AgNet Media’s Citrus Achievement Award in 2022 for her efforts to get the program off the ground and running. CRAFT executive director Tamara Wood says the program has been very popular with growers since its inception in 2019. Tamara Wood worked alongside Carlson as the program was developed. In 2021, Wood took over as CRAFT executive director when Carlson retired. She says the program has been a success with tremendous support from funding agencies and growers. CRAFT has processed five cycles of project funding. Cycle 5 applications closed and are being evaluated with the CRAFT board slated to vote on proposed projects in March or April of this year. Carisa Keller was recently hired as the CRAFT scientific coordinator. She works with growers to help design their experiments along with the CRAFT technical working group to be sure projects will render reliable data. “Participation in Cycle 5 was tremendous. Between Cycle 5 and some carryover applications from Cycle 4, we had more than 220 projects applied for,” Wood says. “This will account for more than 14,000 acres of citrus. The buy-in from growers continues to be amazing. “We do have a large sum of funding for this cycle, but it will not be enough to cover all 14,000 acres, so there will be a wait list, but a large portion of the projects will be funded.” WHAT’S NEW Within the traditional CRAFT new planting program under Cycle 5, a new subset of projects was added to help evaluate trees currently in the Florida Department of Agriculture and Consumer Services (FDACS) Program for Expedited Propagation (PEP). The program’s aim is to speed up the development of trees that have garnered high interest in the grower community due to apparent tolerance to HLB. “The CRAFT board has already approved 11 of the PEP projects,” Wood says. “These plantings will look at comparisons of scions that FDACS and the Citrus Research and Development Foundation (CRDF) have identified as showing promise. These varieties include Parson Brown, Carney 1 and 2, Roble and Donaldson, which will be grown next to a standard Hamlin as a control check.”  A new program was added to CRAFT in 2022 for therapies applied to citrus plantings already in the ground. There have been two cycles of applications for the existing tree therapies program. Growers can choose from four therapies in this program: 1) trunk injection of oxytetracycline (OTC), 2) gibberellic acid, 3) 2-4D and 4) brassinosteroids. Wood says the most popular choice among growers has been the OTC treatment. Between the traditional planting and existing tree programs, there have been 1,303 projects approved. The majority of them are for existing trees. FUTURE FUNDING CRAFT has benefited from generous state and federal funding since its inception. Federal funds come from the HLB Multi-Agency Coordination Group. State funds come from CRDF. Last year, the state granted $35 million to the program. “I believe we will have funding support for another cycle of projects, but I think at some point, we will have to step back and ask when we stop adding new projects and keep moving forward with those already in place,” Wood says. “Each cycle funds a project for six years, so the costs can start adding up with each cycle. I don’t think we are quite there yet, so I do anticipate a sixth cycle.” Sponsored Content

Find UF/IFAS Citrus Resources Online

Daniel Cooper March 12 Citrus Conversations are a video series of in-depth faculty discussions on current topics of interest. By Michael E. Rogers Were you unable to attend a recent University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) event and want to hear what you missed? Many past presentations are available online. The UF/IFAS Citrus Research Website archives presentations made by UF/IFAS faculty at various meetings across the state. These can be found by scrolling down and selecting the “Presentations” drop-down tab to reveal the following options: Research Update Presentations – These recorded presentations are given by UF/IFAS faculty at various workshops conducted by UF/IFAS Extension. Citrus Conversations – These 20–45 minute videos are discussions with IFAS faculty that dig deeper into topics of interest which include CRISPR, trunk injection, plant growth regulators, etc. Citrus Expo Presentations – Presentations are available going back to 2018. The majority of these are PDF files, not recordings. Florida Citrus Growers’ Institute – Organized and hosted annually by the UF/IFAS multi-county citrus Extension agents, presentations are available back to 2019 as both recordings and PDF files. Florida Citrus Show – Held annually in Fort Pierce, this year’s show takes place on April 3. In addition to recorded presentations, the UF/IFAS Citrus Research Website also has links to selected Extension publications that are often available in print at UF/IFAS events. Links to these documents and other Extension resources can be found under the “Resources” drop-down tab, which provides the following options: Plant Improvement/Breeding – Summaries of more than 60 UF/IFAS and U.S. Department of Agriculture citrus rootstock and scion trials are available here as well as the latest version of the Florida Citrus Rootstock Selection Guide. Citrus Production Guide – Formerly known as the Florida Citrus Pest Management Guide, the annual Florida Citrus Production Guide has been expanded to include more horticultural practices that are crucial for managing citrus greening disease. Citrus Nutrition Guide – The latest edition of Nutrition of Florida Citrus Trees includes updated recommendations for HLB-diseased trees. Citrus Research Summary Booklet – Updated annually since 2021, this publication provides short summaries of more than 70 ongoing UF/IFAS citrus research projects. Additional UF/IFAS online resources: Electronic Data Information System Citrus Research and Education Center Indian River Research and Education Center Southwest Florida Research and Education Center Citrus Agents Website Michael E. Rogers is director of the UF/IFAS Citrus Research and Education Center in Lake Alfred. Sponsored Content

Irrigation During the Dry Season to Increase Yield of HLB Trees

 MARCH 5, 2024 IRRIGATION,  TIP OF THE WEEK

By Tripti Vashisth and Mary Sutton

Prolonged water deficits can negatively impact flowering, fruit growth, crop load and fruit quality. Unfortunately, HLB-affected trees are more susceptible to water deficits than healthy trees due to extensive root loss. Observing HLB-affected trees throughout the dry season showed that severely symptomatic trees consistently had lower leaf water potential than mildly symptomatic trees. This suggests HLB-affected trees experience more water deficits as the disease progresses. For this reason, adequate irrigation during the dry season is imperative in preventing drought stress.

This is particularly true for the sweet orange variety Valencia because flowering and fruit maturation periods overlap with the dry season. Researchers hypothesized that more frequent but smaller applications of water would better support the water needs of HLB-affected trees throughout the year. In an experiment, irrigation on control trees ran every other day for two hours (grower standard). Irrigation on the experimental trees ran three times every day for 20 minutes at a time. Both sets of trees received the same amount of water over time, but the experimental trees received water more often and in smaller amounts.

Trees receiving the frequent irrigation consistently had higher soil moisture content and mid-afternoon leaf water potential. This suggests the experimental trees were being maintained at a more well-watered state. The experimental trees also had significantly higher bud, fruitlet and leaf production during the spring flush. In fact, in 2023, the control trees saw a drought-stress-induced flowering event in late May that was not observed in the experimental trees. This all culminated in higher yields (more than double) at harvest over the two-year course of the study.

Tripti Vashisth is an associate professor, and Mary Sutton is a Ph.D. student — both at the University of Florida Institute of Food and Agricultural Sciences Citrus Research and Education Center in Lake Alfred

PGRs for HLB-Affected Trees: An Update

Daniel Cooper February 23 Using the plant growth regulators (PGRs) cytokinin in spring, gibberellic acid (GA) in summer and 2,4-D in late fall can be helpful for HLB-affected trees, horticulturist Tripti Vashisth reported. Her PGR update came during a Feb. 21 OJ Break. Multi-county citrus Extension agent Chris Oswalt hosted the event at the University of Florida Institute of Food and Agricultural Sciences Citrus Research and Education Center in Lake Alfred. Vashisth, who works at the center as an associate professor, said the combination of cytokinin in spring and GA in summer increased yield by approximately 90 pounds per tree in a grower trial. Vashisth noted that the grower in that trial has very little fruit drop. She noted that 2,4-D doesn’t seem to be helpful when fruit drop isn’t an issue. GIBBERELLIC ACID Repeated applications of 10 ounces per acre of GA plus an adjuvant reduces fruit drop and improves yield and canopy growth, Vashisth said. She added that GA will keep fruit green and said a 2- to 4-month gap should be left between the last application and harvest. When an appropriate gap is given between the last application and harvest, GA doesn’t reduce Brix, she said. Vashisth recommended GA applications be made on Hamlin oranges from August to November and on Valencia oranges from September to December. GA applications should be avoided from January to May. Vashisth said spring (March to May) GA applications enhance fruit set, and enhanced fruit set is not desirable with current tree conditions. 2,4-D Repeated applications of 2,4-D counteract the abscission signal, thus enhancing fruit retention, Vashisth reported. She emphasized that proper timing of applications is critical; applying 2,4-D too early or too late won’t help. BEST OF BOTH WORLDS Combining GA and 2,4-D gives the “best of both worlds in reducing fruit drop,” Vashisth reported. She said small fruit drops first, and 2,4-D can stop small fruit from dropping “whereas GA keeps fruit growing longer, thus reducing the drop.” If severe fruit drop is a problem, it’s recommended to use 2,4-D plus GA. “Otherwise, a summer-fall spray of GA is recommended,” Vashisth stated. Learn more from Vashisth about PGRs for HLB-affected trees.

Tips for Trunk Injection of Oxytetracycline

Daniel Cooper February 13 By Ute Albrecht and Ozgur Batuman The following are important tips to follow for proper trunk injection of oxytetracycline as a citrus therapeutic. APPLICATION TIMING The tree hydration status is important for uptake and distribution of the injected formulation. Therefore, ensure that trees are well watered before performing injections. Injections should be performed after the harvest and in compliance with the 180-day preharvest interval. To ensure efficient uptake and distribution, inject when the leaves are fully expanded. Avoid injecting during leaf flush to prevent leaf deformations. For optimal uptake and distribution, injections are best performed during spring or early summer and during mid- to late morning (9:00 a.m. to 12:00 p.m.), when transpiration rates are highest. To achieve the best results, inject trees as soon as possible after preparing the formulation. This will minimize degradation from heat and UV and help preserve the product’s efficacy. INJECTION TECHNIQUE Before performing injections, measure the diameter of the tree trunk to determine the appropriate dosage and size of the injector. Choose the smallest drill bit recommended for the trunk diameter. Find a site on the tree trunk with no existing damage or disease. The label recommends injecting in the rootstock, but this may not always be possible. Inject in line with the crotch of the scaffold branches, especially if the tree trunk is short. Do not inject right beneath a major scaffold branch as the formulation will then only move into the part of the canopy that is supported by that branch. Use a sharp brad-point drill bit. Do not drill/inject deeper into the trunk than necessary. For bearing trees, the depth should not exceed 1 inch when using the large FlexInjectTM injector and a 17/64-inch drill bit. The deeper (older) wood is less metabolically active than the newer wood and therefore less effective in compartmentalizing the wound caused by the injection. Injecting too deep will also hinder effective distribution throughout the tree. ADDITIONAL ADVICE Implement good tree care, including proper irrigation and nutrient management, to support tree recovery after injection. Continue to manage psyllid populations with insecticides. Trunk injection of oxytetracycline is no replacement for psyllid control! Maintain detailed records of the trunk-injection process, including date, type of injection material used, dosage and any observations made during and after the treatment.   If possible, mark the trees with failed injections. This may be an indication of citrus blight. If the number of failed injections in the block is high, consider testing the trees for citrus blight by injecting water with a syringe. If blight is confirmed and the trees are not in good health, replace those trees and do not attempt injections again. Follow the label instructions. The label is the law. Ute Albrecht (ualbrecht@ufl.edu) and Ozgur Batuman (obatuman@ufl.edu) are associate professors at the University of Florida Institute of Food and Agricultural Sciences Southwest Florida Research and Education Center in Immokalee. Sponsored Content

Crop Transformation Center Takes Aim at HLB Resistance

The University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) has established itself as a leader in new technological frontiers like artificial intelligence (AI). In fact, the school has the 15th most powerful computer in the world. The HiPerGator, as the computer is called, will assist in AI development and on many other technological fronts. Another frontier where UF/IFAS is doubling down is the use of gene editing and CRISPR to breed better and more resilient plant varieties. These technologies can transform plants to be resistant to diseases, have improved nutritional values, enhanced capability to withstand environmental conditions and more. To better organize and prioritize these research efforts, the university launched the Crop Transformation Center last year. The center was given a $2 million boost by University of Florida President Ben Sasse. Other support has come from the Florida Department of Citrus and the Citrus Research and Development Foundation. The $2 million will cover two years of research and facility upgrades. In that time, UF/IFAS staff will build out the infrastructure needed for the center, including greenhouses, growth chambers, supplies and personnel. Simultaneous to building facilities and hiring staff, scientists are already conducting research. Charlie Messina, the director of the new center, brings both academic and private industry experience to the job. Prior to joining UF/IFAS, he was employed by Corteva where he worked with the company’s gene-editing and crop-improvement groups. Charlie Messina joined UF/IFAS in 2022 and became director of the Crop Transformation Center last year. “After many years in the private sector, I wanted to get back to working with students. In January 2022, I was appointed professor in the UF/IFAS horticultural department as part of the university’s overall AI initiative,” Messina says. “Then I was approached about leading the Crop Transformation Center and leveraging my experience in industry and academia to think differently about how we can help Florida growers deal with real problems on their farms. How can we bring the best of both worlds — the industry side of focusing on solving problems combined with all the talent and intelligent machinery we have at UF/IFAS? That is what we are hoping to do through the center.” TARGETING HLB The Crop Transformation Center’s first big target will be HLB. It will organize and enhance research aimed at developing new citrus varieties resistant or tolerant to the disease. “We have some of the best scientists in the world working on citrus here at UF/IFAS,” Messina says. “The more that I talk to them, the more impressed I am. My job (as director) is to work them to help growers and get those solutions in their hands more quickly.” Messina describes the center’s methodology as an end-to-end approach. At one end, you start with the grower’s problem. At the other end, you start working on the science of the solution, regulatory clearances and educating the public about why the solution is needed. He says all this work needs to be happening in unison, not in silos, which often is the case in academia. “We need to provide the right solution to the right problem, rather than to have an academic idea and let’s see if it works and is useful,” he says. “Here we are targeting a very specific problem or goal and have everyone on the team working to get the solution to the grower. This is what makes the Crop Transformation Center unique.” TURBOCHARGING EFFORTS “The center will allow us to much more effectively employ biotechnology tools to increase the speed and accuracy of our plant breeding,” says Scott Angle, University of Florida provost. “We already have the nation’s leading university plant-breeding program, and the center will turbocharge those efforts. We’ll start with citrus because that is a commodity in crisis.” Scott Angle (left) has been a proponent of bringing in the expertise of private sector talent like Charlie Messina (right) to move research from the lab into the grove more quickly. While the Crop Transformation Center is new, citrus plant breeding utilizing advanced technological approaches is well underway. That work stretches from traditional breeding to CRISPR and transgenic modification to impart resistance to HLB. One such project is the work being conducted by Nian Wang, a molecular geneticist with UF/IFAS, who is utilizing CRISPR technology to develop HLB-resistant citrus varieties. Wang has created several gene edits that appear to impart resistance to the disease. Those selections are headed to groves for field trials soon. “The center will provide a broader framework for what Dr. Wang is working on and make sure it flows more smoothly toward helping solve the grower’s problem,” Messina says. “That is the case with all the scientists working on their projects to transform citrus plants. “When we look at this transformation, we want to use the varieties that the farmers are already familiar with. We want to be as close to the tree the growers know how to grow as possible. For example, we can take an early Valencia, do the gene editing and make the plant have a better immune system (against HLB). And we can assist this research through its development and field trials while also working on templates to help move things through the regulatory process more smoothly.” Research by Zhonglin Mou, UF/IFAS professor of microbiology and cell science, is also being supported by the center. His work is developing transgenic HLB-tolerant varieties. He has modified five Hamlin varieties and one Duncan grapefruit variety. These lines were planted in field trials starting in 2019. While they have become infected with HLB, so far they show low symptoms of the disease. Fruit quality data will be collected over the next couple of seasons. Requests to deregulate and release these lines are underway with an estimated timeframe for approval of two-plus years. WORKING WITH REGULATORS Eric Triplett, UF/IFAS chair of microbiology and cell science, is playing a key role in developing a process to move these gene-edited and modified citrus plants through the regulatory process. “We want to be proactive and have started working with the U.S. Environmental Protection Agency and other regulators to develop the right presentation (of data and safety) to move these genes through the approval process as quickly as possible,” Messina says. “There are well established procedures for other crops, but we are developing the best approach for these transformations in citrus.” With the center up and running, Messina says the push now is to move these technologies from an academic exercise to something growers can plant in the grove. “The sooner we test these trees in field conditions, the better. That’s happening with transgenic trees now and with Dr. Wang’s CRISPR trees soon. Then, if these trees perform like we hope they will, the next steps will be achieving the approval from regulators and getting the technology in commercial trees.” Messina says that could take another few years, but the framework is in place to make it happen more quickly now through the center’s efforts. OTHER CROPS COMING While citrus is the first target, the Crop Transformation Center will be working on other important crops in Florida, including blueberries, strawberries, broccoli, sugarcane and more. About the Author Frank Giles Editor-in-Chief, AgNet Media Publications Sponsored Content

By Tripti Vashisth 

Huanglongbing (HLB) severity is associated with small fruit sizes and lower fruit numbers at harvest. Moreover, small fruit are more likely to drop and drop earlier during preharvest fruit drop. Unfortunately, management practices suggested to increase fruit size or reduce drop have had mixed results.

So, before looking for ways to increase fruit size and number, it is necessary to first identify when and why differences in size and retention occur. To do this, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) researchers followed fruit on mildly and severely HLB-symptomatic trees from bud to harvest.

RESEARCH RESULTS
Mild trees had a higher rate of flowering and fruit set, which suggests HLB affects fruit number early on. Mild trees have a denser canopy with more fruiting wood and better source-to-sink ratio available for flower and fruit production. Maintaining canopy density should be a priority in maintaining fruit numbers. While HLB-affected trees are more susceptible to drought stress, mild trees experience less water deficits. This may contribute to their improved flowering and fruit set as these processes correspond with the Florida dry season.

UF/IFAS researchers are currently investigating irrigation practices to further mitigate this susceptibility. An experimental treatment involved irrigating three times daily for twenty minutes each while the control involved irrigating every other day for two hours. The experimental schedule increased bud production and fruit set while improving yield at harvest. Trees under the control regime experienced a late burst of flowering consistent with drought stress. This was not seen in the experimental schedule, which suggests that frequent, smaller doses of irrigation maintain trees in a well-watered state. 

TAKE-HOME MESSAGES

• Canopy density largely limits flowering, fruit set and final fruit numbers. 
• Mildly affected HLB trees experience less water deficits than severely affected trees.  
• Frequent, small doses of irrigation increase bud production and fruit set leading to improved yield.

Acknowledgment: This is a UF/IFAS Citrus Initiative project funded by the Florida State legislature.

Tripti Vashisth is an associate professor at the UF/IFAS Citrus Research and Education Center in Lake Alfred.

Use of PGRs to Reduce Preharvest Fruit Drop

Daniel Cooper Dec 4 By Brandon Page The effects of HLB on the Florida citrus industry are widely known and well understood by those who depend on the citrus industry for their livelihood. It has been over a decade since the real impact of HLB was recognized. The first indication of HLB I recall seeing was a significant loss of foliage and unprecedented fruit drop in the later part of 2012 in many groves in Central Florida. I did not know it at the time, but the fruit drop and foliage loss I was seeing would become universal in the industry and something every grower would have to address. Indeed, a recent report from the U.S. Department of Agriculture National Agricultural Statistics Service, shows that the estimated fruit drop in 2022–23 was as high as 76% for early oranges and 70% for Valencia oranges. GROWER EXPERIMENTS BEAR FRUIT Several experimental therapies have been implemented to address preharvest fruit drop, many of which provided little to no impact. But, in the past three years, several growers began experimenting with exogenous applications of plant hormones, products commonly known as plant growth regulators (PGRs). There is a lengthy list of plant hormones which can be bought and applied, but most growers have focused on the use of gibberellic acid and synthetic auxin. Reports from numerous growers indicated successful treatments that resulted in a reduction in preharvest fruit drop. CRDF PROJECT DETAIL At the direction of the Citrus Research and Development Foundation (CRDF) board of directors and Research Management Committee (RMC), CRDF staff reached out to several of these growers to design a research project which would help identify the best use of the PGRs. Several commonalities began to appear in their various PGR programs. Consequently, a list of nine treatments was formulated that would be evaluated against an untreated control (see Treatments Tested sidebar). In 2022, the CRDF board and RMC settled on evaluating the PGR treatments at six sites (three Hamlin and three Valencia) spread throughout the three primary ecoregions (Ridge, Southwest and East Coast) of the Florida citrus industry. A complete scope of work was developed and put out to bid for public and private researchers. All spray applications were applied with a Rears Pak-Blast air blast sprayer. The spray volume for all treatments was 200 gallons per treated acre. The rate for the 435 spray oil was 2% v/v, and the rate for the Kinetic organosilicon surfactant was 0.05% v/v. The timing of the spray application in Treatments 3, 4 and 5 was July, September and November for Hamlin sites. The same spray schedule was used for the Valencia sites with the addition of 0.7 ounces per acre applied in late December. The timing of the spray applications for Treatments 6, 7 and 8 was August and October for both the Hamlin and Valencia trial sites. Treatment 9 was applied at the first sign of fruit color break for each scion. Treatment 10 was applied to the Hamlin sites in September and to Valencia sites in November. Treatments 1–8 were applied during daytime normal working hours. Treatments 9 and 10 were applied at night. John Curtis of Better Crops LLC was selected to conduct the research for this project. Spray applications began in July 2022 and followed the predetermined treatments. The trial work concluded in April 2023. Unfortunately, Hurricane Ian severely impacted the Hamlin Ridge and East Coast sites. TRIAL RESULTS This project focused on evaluating yield, fruit quality and fruit drop. There were significant differences identified at each trial site. The uniformity of data was better in the Valencia sites than in the Hamlin sites because of the negative impact of Hurricane Ian. Treatment 8 produced the most consistent reduction in fruit drop across all trial sites, regardless of hurricane impact. Treatment 8 is a mixture of Citrus Fix and 435 spray oil (2% v/v). A key takeaway from this trial is the effect a surfactant or horticultural spray oil has on the efficacy of the PGRs. Data suggests enhanced efficacy with synthetic auxin PGR use by mixing it with 435 spray oil. Fruit quality at the Valencia sites was uniform and conformed to current industry standards. The Hamlin fruit quality varied greatly. The Southwest Hamlin site produced excellent fruit quality data. The Ridge site generated fruit quality data that was in line with current industry averages for Hamlin. The East Coast Hamlin site was severely damaged by Hurricane Ian, and the fruit quality data, regardless of treatment, was well below industry standards. Treatment 10 was unique in that the two PGRs utilized for this trial were tank-mixed and sprayed together. Some growers had expressed concern or had no experience with tank-mixing two PGRs. There are examples of mismanaged PGR applications causing negative impacts on plant health and flowering in several crops. In this trial, no adverse effects on tree health or function were observed. RESEARCH CONTINUES The CRDF board and RMC approved a continuation of this trial for a second year at their July meetings. The trial hopefully won’t be impacted by a major storm. The same variables will be evaluated as in the first year, but a few modifications to the treatment list for the second year have been made. These modifications eliminated the least effective treatments identified in year one and expanded upon the tank-mix of gibberellic acid and synthetic auxin. Year two of the study will have five sites, not six. The Hamlin site in Okeechobee was almost a complete loss due to Hurricane Ian and will not be a part of the second year of this study. A comprehensive report on this research can be found at tinyurl.com/mrem9f5e on the CRDF on the CRDF website. Brandon Page is the field trials coordinator for CRDF.

Calling All Florida Citrus Growers for Survey

Jim Rogers Nov 7 There’s a lot going on in Florida citrus. New trunk-injection therapies have been approved to treat HLB as groves bounce back from last year’s hurricanes. It’s a good time to get a sense of the mood of growers as we start the new Florida citrus season. If you are a grower or a consultant/caretaker (who can answer generally on behalf of your growers), we’d like to ask you to take a few moments to respond to this brief survey. It won’t take a lot of your time, and your input will provide valuable insights on the state of Florida’s citrus industry. Results from the survey will be published in the January and February issues of Citrus Industry magazine. One of the key topics of the survey is grower participation in applying new HLB therapies. The survey asks for observations on how these therapies are impacting tree health. In addition, the survey seeks to answer how many growers are planting new trees and which varieties and rootstocks seem to be the most popular. The survey also allows growers to provide comments on where they believe the industry stands today and going into the future. We thank you for your participation and appreciate CYAN 365 for sponsoring this year’s survey! NOTE: Survey results will only be published in aggregate. Your individual results will not be published. Click here to take the survey. About the Author Frank Giles Editor-in-Chief, AgNet Media Publications Sponsored Content