The All In For Citrus Podcast

In November, academia from around the world gathered in Jeju, Korea, for the 2024 International Citrus Congress. A contingent of researchers from the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) attended the event.

Michael Rogers, director of the UF/IFAS Citrus Research and Education Center, was among the attendees. He discusses the trip in the November episode of the All In For Citrus podcast. Rogers describes citrus growing on the island of Jeju. There’s about 54,000 acres of citrus grown there with annual production of about 15 million boxes. There is no confirmed presence of HLB on the island.

HLB was a major topic of discussion during the event. Water availability was also a focus of the presentations. Many citrus production regions are facing water shortfalls. This is expected to get worse as the climate changes and more demand is put on water supplies.

Brazil is one of those regions dealing with water availability. The country’s last crop was reduced by about 20% due to drought stress. Brazil also has seen a spike in HLB infection rates, which is forcing growers to plant new groves north of the current main growing regions.

Mohammad Shahid, UF/IFAS assistant professor of horticulture, also joined the podcast to provide an update on the cold-hardy citrus region. Production continues to expand in the area with some 7,000 to 8,000 acres of citrus.

Also in the November episode, Flavia Zambon discusses a field day hosted at the UF/IFAS Indian River Research and Education Center in Fort Pierce, Florida. The field day featured a tour of the experimental Millennium Block, which is evaluating HLB tolerance of various rootstock/scion combinations. The block is one of the largest trials for HLB tolerance in grapefruit.

On Oct. 9, Hurricane Milton made landfall near Siesta Key, Florida, leaving a path of destruction in its wake. Some key citrus-growing regions felt impacts from the storm. While damage was spotty, fruit loss was significant for some. Now, the waiting game is on to see how much more fruit drops from the stress to trees caused by the storm.

The University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) quickly organized a webinar after the storm to provide growers with information about resources available to rehab trees and seek financial assistance. The webinar is the topic of the October All In For Citrus podcast.

Michael Rogers, director of the UF/IFAS Citrus Research and Education Center (CREC), shares highlights of the webinar and gives updates on what he was hearing and seeing in groves after the storm. He also discusses how CREC facilities and groves made it through the storm.

Chris Oswalt, UF/IFAS citrus Extension agent for Polk and Hillsborough counties, talks about the path of the storm and how it impacted various citrus-growing regions. He says the storm had a large wind field with 70 to 80 mph winds reaching well inland across Florida. He also draws some comparisons between Hurricane Milton and Hurricane Ian, which struck in 2022.

Tripti Vashisth, UF/IFAS associate professor of horticultural sciences, joins the podcast to provide guidance on the use of plant growth regulators to help reduce the amount of fruit drop in the wake of the storm. Applied in a timely manner, 2,4-D can reduce delayed fruit drop that could be caused by Milton.

To learn more about Hurricane Milton damage and resources available to help growers, don’t miss the October episode of All In For Citrus. The podcast is a partnership between UF/IFAS and AgNet Media.

Mark Ritenour, professor of postharvest technology with the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), joined the September episode of the All In For Citrus podcast to provide a recap of Packinghouse Day. The event was held Sept. 12 at the Citrus Research and Education Center (CREC) in Lake Alfred.

Based at the Indian River Research and Education Center in Fort Pierce, Ritenour has worked with UF/IFAS for 26 years. Much of his research has focused on the fresh fruit industry. That is also the focus of Packinghouse Day, which marked its 63rd year in 2024.

Ritenour said despite the sharp contraction of the fresh citrus segment in recent years, Packinghouse Day has maintained a loyal following of growers, packers and stakeholders who value the meeting and the opportunity to get together with industry peers.

The educational program touched on a wide range of topics. Scott McClure, with the Florida Department of Agriculture and Consumer Services, informed growers and packers about the services the agency offers to help prepare for food safety audits and other audits.

The meeting also addressed movement of fruit between states.

“There are agreements between Florida, Alabama and Georgia on the movement of fruit, but you must contact your respective departments of agriculture (and get clearance), along with preharvest grove inspections to get certificates to harvest the fruit and transport it across those boarders,” Ritenour said. “The good news is you can do it, and there are procedures in place (to accommodate the movement).”

There was a presentation from Paul Mears of the U.S. Department of Agriculture on the phytosanitary requirements of key export markets for fresh citrus. Other topics addressed included disease management and requirements to avoid the potential of pest movement in shipments. Ritenour discusses these presentations in the podcast.

A highlight of Packinghouse Day was the John T. Lesley Award of Excellence presentation. The honor was first presented in 1981 to John T. Lesley for “recognition of an individual for outstanding leadership and service on behalf of the Florida fresh citrus industry.” This year’s winner is Lindsay Raley Jr. of Dundee Citrus Growers Association.

Also in the podcast, Michael Rogers, CREC director, provides a rundown of a busy slate of citrus events planned for this fall. Don’t miss the September episode of All In For Citrus. The podcast is a partnership between UF/IFAS and AgNet Media.

The August episode of the All In For Citrus podcast features highlights from this year’s Citrus & Specialty Crop Expo. The event included two citrus educational sessions that covered a wide range of topics, including HLB management, other pest management topics and new varieties.

Michael Rogers, director of the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Citrus Research and Education Center, said the citrus research team relies on input from growers to develop the seminar program and tries to cover hot-button issues of the moment.

“Obviously, oxytetracycline (OTC) trunk-injection therapies are a real hot topic in the industry, so we had a couple of presentations at the Expo on the topic,” Rogers said. “We also heard about some research from our foundational programs on things like nutrient and irrigation management.”

Rogers added that a few speakers discussed longer-term research to deliver an HLB-resistant citrus tree. Among those speakers was Charlie Messina, who is the director of the UF/IFAS Crop Transformation Center.

Ute Albrecht, UF/IFAS associate professor of plant physiology, joined the podcast to discuss her presentation on research regarding OTC applications. She said growers have learned a lot about trunk injection in the past two seasons and they are applying that knowledge in the grove.

Albrecht discussed how citrus trees benefit from multiple trunk-injection sites to split applications and better distribute OTC benefits throughout a tree. This practice also helps reduce any phytotoxicity responses after applications, which were observed this year.

Manjul Dutt, UF/IFAS assistant professor of horticultural sciences, also joined the podcast to talk about his presentation at the Expo featuring early-season varieties that have shown improved tolerance to HLB. Chief among those varieties is Parson Brown, which is more than 100 years old and has captured grower attention due to its productivity despite HLB infection.

To hear more about these presentations from the Citrus & Specialty Crop Expo, don’t miss the August episode of All In For Citrus. The podcast is a partnership between UF/IFAS and AgNet Media.

As citrus growers try to stabilize production in the midst of endemic HLB, maintaining the industry’s infrastructure is critically important. Two key sectors of that infrastructure are citrus nurseries and juice processors.

In the July episode of the All In For Citrus podcast, Michael Rogers, director of the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Citrus Research and Education Center, discusses research efforts aimed at helping those two sectors.

“One of the vital parts of our industry is the citrus nursery segment, and right now, they are having a hard time moving plant material and getting orders,” Rogers says. “If these nurseries go out of business, we won’t have anywhere to go to get our trees. So, we feel it is really important that we help support them.”

Among the efforts to support nurseries is the promotion of growing dooryard citrus through the UF/IFAS Home Citrus Project. Dooryard citrus has been an important lifeline for nurseries as commercial demand has fallen off due to HLB.

“Homeowners typically have one or two trees in their yard and want to baby those trees,” Rogers says. “We have stepped back into the homeowner arena with some of our educational programs.”

The project is engaging with Master Gardeners to give them tools to teach about best practices when it comes to raising a citrus tree at home. A homeowner newsletter and a website dedicated to home growing are also part of the project.

On the juice processing side, Rogers discusses research by Yu Wang, UF/IFAS associate professor of food science. She has recently identified a compound in citrus peels that helps inhibit a bacterium in the human gut that can contribute to cardiovascular disease.

“In an average year, we generate 5 million tons of orange peel waste just from processing round oranges,” Rogers says. “About half of that goes to cattle feed, but the other half is basically thrown away at the processors’ expense.”

Wang’s research could lead to a dietary supplement to encourage heart health using orange peel as the source. This could give orange juice processors a much needed new revenue stream.

To hear more about efforts to support nurseries and processors, listen to the July episode of All In For Citrus. The podcast is a partnership between UF/IFAS and AgNet Media.

The educational seminars at the June Florida Citrus Industry Annual Conference covered a wide range of topics intended to give growers hope that progress is being made in the fight against HLB.

During the June All In For Citrus podcast, Michael Rogers, director of the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Citrus Research and Education Center, discussed presentations UF/IFAS scientists made at the conference.

“We had two of our faculty speak on topics of relative importance and things growers can incorporate in the grove now,” Rogers said.

Ute Albrecht, UF/IFAS associate professor of plant physiology, spoke about her latest research on trunk-injection therapy. She presented some new data collected over the past season.

“In general, what she presented was most of her trial sites are showing improvements in health metrics they are measuring in terms of canopy growth, overall appearance of the trees and some increases in fruit yields and maybe some Brix improvements in some locations,” Rogers said. “The results have not all been consistent, and she will tell you that not all trees are the same. There is a mixed bag of results out there. Every tree is a different individual, so they are going to respond (to treatments) differently. But over time, as the trees have received multiple treatments, we are hopeful those benefits will increase.”

Albrecht observed where growers do double-sided injections on the tree trunk, oxytetracycline (OTC) is distributed more evenly throughout the tree. Rogers said that might not be practical for growers in every grove and on every tree, but there is evidence it is beneficial.

Tripti Vashisth, UF/IFAS associate professor of horticultural sciences, presented her research on the use of plant growth regulators (PGRs). Rogers noted that PGR applications will be a key benefit when growers must take a break applying OTC next season per label requirements.

One new observation is that gibberellic acid applied via irrigation along with foliar applications provides better results than foliar applications or chemigation alone. 

“Where gibberellic acid was foliar applied and supplemented by chemigation was where she saw the biggest benefit in terms of fruit yield increases and tree health increases,” Rogers said. “That was new and interesting information.”

Get more details on this research and more in the June episode of All In For Citrus. The podcast is a partnership between UF/IFAS and AgNet Media.

Late spring and early summer are busy times for University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) citrus scientists. They are out in the field preparing new research projects for the coming season and assessing data from ongoing projects.

Michael Rogers, director of the UF/IFAS Citrus Research and Education Center, discusses some of that work during the May All In For Citrus podcast episode. He is particularly excited about some variety development work moving into field trials to be tested in the real-world environment to see how well trees resist HLB and perform in general.

Manjul Dutt, UF/IFAS assistant professor of horticultural sciences, will be planting some of his transgenic citrus varieties, which have shown resistance to HLB.

“These are replicated trials. And these varieties have not been in the field yet, so it is exciting to see those going out into the field,” Rogers says.

Another project progressing into field trials is work by UF/IFAS geneticist Nian Wang. He is using gene-editing techniques and CRISPR to develop citrus plants resistant to HLB. Work in the laboratory and greenhouse has been very promising. Now, these non-transgenic plants are going out into the field for the real test.

“We are going to be guardedly optimistic about them and watching them over the next few years to see how they hold up, perform and resist HLB,” Rogers says. “We will keep everyone updated on how they are looking. But for the first six or eight months, we don’t expect to have much to report. It is usually after about a year that we can start reporting on disease status, and then after about three years, we’ll start seeing and reporting on fruit and yields.”

Learn more about these research projects in the May episode of All In For Citrus. The podcast is a joint partnership between UF/IFAS and AgNet Media.

April was a busy month for citrus events. The Florida Citrus Show was held April 3 in Fort Pierce followed by the Florida Citrus Growers’ Institute in Avon Park on April 9. These events were a topic of discussion between All In For Citrus podcast host Frank Giles and Michael Rogers, director of the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Citrus Research and Education Center, during the April episode.

The Florida Citrus Show was held at the neighboring UF/IFAS Indian River Research and Education Center (IRREC) and U.S. Department of Agriculture-Agricultural Research Service U.S. Horticultural Research Laboratory.

Rogers shared some news regarding the IRREC in the podcast; a new center director has recently been named. Mark Kistler will take the leadership position in June. Kistler currently is professor and dean of the School of Agriculture and Natural Resources at Abraham Baldwin Agricultural College in Tifton, Georgia.

“Mark is a longtime Floridian originally,” said Rogers. “He grew up in Winter Haven. We are glad to see him coming back to lead that station as they move forward with their research plans.”

Rogers also provided some highlights from the Florida Citrus Growers’ Institute. The event covered an array of citrus production topics.

“We heard an update from Dr. Ute Albrecht on oxytetracycline trunk injections. She continues to see some promising data in her trials in terms of yield increase and possibly some Brix increase,” Rogers said. “They are still looking at how much fruit quality is impacted, but it is probably more of an overall tree health issue, as they are managing the HLB bacteria levels and seeing results that manifest in terms of leaf growth and how that affects fruit quality down the road. She also gave growers tips based on what she’s finding in her research.”

To hear more about April’s citrus events and to learn about ways to maximize citrus irrigation, don’t miss this episode of All In For Citrus. The podcast is a partnership between UF/IFAS and AgNet Media.

As winter transitions to spring, it is important to monitor irrigation needs in citrus. This is especially true in Florida, where nearly all trees are infected with HLB. Irrigation was a topic of discussion during the March episode of the All In For Citrus podcast.

Michael Rogers, director of the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Citrus Research and Education Center, says this is a key time to be thinking about irrigation and how it will affect next year’s yields.

“We’ve come out of a time where it has been relatively wet. It is not evenly distributed rain throughout the season, but for the central and south part of the state, we are anywhere from a little above normal to as much as 4 inches above normal rainfall,” Rogers says. “So, we’ve come out of a pretty good winter compared to past years. That is good news to help these trees recovery a little bit and deal with things post-hurricanes. But right now, we are approaching what is typically the driest time of year and when we start seeing the temperatures rise.”

According to Rogers, all of this occurs while bloom is happening, so now is a critical time for irrigation and not letting trees experience water deficits. Proper irrigation can be the key factor in setting the crop for the coming year.

With the root loss trees have experienced due to HLB, more frequent irrigation is even more important because there are fewer roots in the ground to absorb moisture. Rogers reviews some other key irrigation considerations during the episode.

Lauren Diepenbrock, UF/IFAS entomologist, also joins the podcast to talk about bugs and snails. She shares tips on scouting and management of the pests.

Don’t miss the March episode of All In For Citrus. The podcast is a partnership between UF/IFAS and AgNet Media.

Florida citrus growers are now well into their second application of oxytetracycline (OTC) via trunk injection to treat HLB. Per the label of both registered OTC products, after two applications, there is a one-year treatment pause.

So, growers will be formulating plans on what to do during the off-season for OTC-treated trees. That was the subject of discussion during the February episode of the All In For Citrus podcast. Michael Rogers, director of the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Citrus Research and Education Center, advised that a solid fertilizer program is going to be critical.

“We can’t stress enough the importance of nutrition when we are dealing with HLB. I know that sounds like a broken record because we are constantly saying that, but it really is the No. 1 thing that you can do to keep trees productive and healthy,” Rogers said. “In some of our research blocks, we really have had some excellent results with some of our more expensive fertilizer programs. After four or five years, these trees have really healthy root systems, the canopies are lush and green, and the Brix has been very high in fruit. This is where we’ve been using these expensive controlled-release fertilizer applications.”

The high cost of these nutrition programs can be difficult for growers to afford, so researchers are beginning to seek out which elements are most responsible for the great results evident in those blocks.

“We do know there are differences in the micronutrient and macronutrient amounts and how they are delivered to the tree,” Rogers said. “We have allocated some funds to seek out how we can develop the right blend of minor and major nutrients at a cost much lower to growers.”  

To hear more about this research and catch up with Flavia Zambon, who was recently named UF/IFAS assistant professor of production horticulture of citrus and other tree crops, don’t miss the February episode. Also in the podcast this month is a sneak peek at upcoming events, including the Florida Citrus Show.

The All In For Citrus podcast is a partnership between UF/IFAS and AgNet Media. Find all the episodes here.