From the Archives: Citrus Greats - Walter T. Swingle

Similar to any scientific field, early researchers paved the way for the current researchers. This post will acknowledge just one of the many monumental discoveries made in the citrus industry. Starting with Walter T. Swingle, he was a botanist sent to Florida from Washington, D.C. He was originally sent to Florida with the goal of researching the citrus disease plaguing groves at the time. During his time in Florida, he became a part of some of the early research concerning hybrids and hybridization. Swingle is specifically credited with creating the Tangelo, a cross between a tangerine and a pomelo.

Hybridization is a beneficial tool because it allows researchers to combine the most desirable characteristics of two different species to create an entirely new species. This is different from genetically modified organisms, or GMOs, because the genes in GMOs have been altered or enhanced while hybridization takes advantage of the natural traits found in each plant species. This can be done by collecting a sample of the DNA found in each species, unwrapping it, and pairing them with one another to create a DNA helix that has one strand from species A and one strand from species B.

Herbert J. Webber worked alongside Swingle to perfect their hybridization techniques. The pair published several papers, books, bulletins, and pamphlets together discussing the research they had conducted and providing growers with helpful information to aid in the efficiency of growing citrus groves. Webber and Leon D. Batchelor then published The Citrus Industry. This book detailed the history of the citrus industry, botany, and methods used to breed citrus. Citrus growers used these books to aid in their growing techniques and to learn more about the citrus industry. Although not mentioned, there are numerous other researchers and scientists who played a fundamental role in the advancements of the Florida Citrus Industry.

Walter T. Swingle was inducted into the Florida Citrus Hall of Fame in 1962 as part of the inaugural class: https://floridacitrushalloffame.com/inductees/walter-tennyson-swingle/.

Written by Tanzy Zviitwah, Florida Citrus Hall of Fame Fellow
In partnership with Florida Southern College’s McKay Archives Center
Spring 2024

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Sources:

Johnson, Alexander. “How Does Plant Hybridization Work?” ScienceOxygen, September 14, 2022. https://scienceoxygen.com/how-does-plant-hybridization-work/.

Mack, Thomas B. Citrifacts II: A Portion of Florida Citrus History. Bartow, Florida: Associated Publications Corporation, 1998.

From the Archives: Citrus Canker

Citrus canker is caused by a bacteria that eats the flesh and leaves of fruit. This bacteria is not harmful to humans and the fruit is still edible. However, the fruit is now difficult to sell due to the ugly sores that are created by the canker bacteria. This bacteria can also cause fruit to drop from the tree prematurely stopping it from ripening.

In the early 1900s, there was a widespread outbreak of canker throughout Florida. Frank Starling was hired by the Florida Citrus Growers and the Citrus League to see if he could aid in the battle against canker. Between 1913 and 1933, the state of Florida spent approximately $1.3 million in their attempts to eradicate canker. During this battle against canker, infected trees were burnt down to ensure that they could not spread the bacteria to other trees in the area. It is speculated that the canker bacteria traveled to the States via citrus seedlings from Japan.

There was a reemergence of citrus canker in the 1980s, and it was declared eradicated in 1994. However, there was a report of canker in Miami-Dade County the following year, in September 1995. Before the eradication efforts were successful, a hurricane spread the bacteria to several other counties. By 2005, $2.1 million worth of commercial grade citrus had been destroyed. In 2006, the eradication efforts were forced to stop because it had become impossible to eradicate canker due to how widespread it had become.

Currently, canker is still active in citrus groves with the majority of infections taking place between April and July. Growers have learned how to deal with the bacteria; applying copper containing products periodically to produce has been known to deter canker in citrus. Although, it should be noted that copper is not a guaranteed deterrent to the bacteria. As there are no known cures to the bacteria, these methods will have to be sufficient for the time being.

Written by Tanzy Zviitwah, Florida Citrus Hall of Fame Fellow
In partnership with Florida Southern College’s McKay Archives Center
Spring 2024

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Sources:

Dewdney, M. M., M. Zekri, P. D. Roberts, and J. D. Burrow. “Homeowner Fact Sheet: Citrus Canker.” UF IFAS Extension, University of Florida, June 4, 2018. https://edis.ifas.ufl.edu/publication/PP116. 

 

Mack, Thomas B. Citrifacts. Bartow, Florida: Associated Publications Corporation, 1992.

From the Archives: Soil Science Foundation

In 1939, the Soil Science Foundation was started by a group of farmers in Dade City who were looking to come up with solutions that they were facing with their various crops; the Soil Science Foundation is credited with several scientific accomplishments. Their first headquarters was a small building on the campus of Florida Southern College, and they did not relocate off campus for 10 years.

When the Foundation started, they were running experiments on the fertilization of sandy soils at the Short Grove in Lake County. Sandy soils do not hold nutrients well, meaning fertilization is necessary to ensure that crops are able to obtain the necessary nutrients for growth. However, over fertilization can be harmful for plants as it will change the pH of the soil, suffocate the soil, and cause root damage. The goal of the experiments being run by the foundation was to determine the necessary amount of fertilizer.

During this time, the Foundation also researched the sustainability of Florida flatwoods for citrus planting. Florida flatwoods make up a large portion of Florida’s landscape. Flatwoods are ideal for citrus cultivation because of their sandy moist soils. Citrus does well in sandy soils because it provides good drainage, which prevents root damage from taking place. Planting in flatwoods also helps with irrigation because of the water deposits that are typically found within these flatwoods. However, there may be some disadvantages to planting citrus on these lands. During wet seasons, the soil can become overly saturated due to the water deposits already existing in the soil, they are at risk to develop frost that can cause freeze in citrus, and cultivating citrus in these regions could negatively impact the environment and decrease the biodiversity of the region. The goal of the experiments targeting citrus cultivation on the flatwoods was to determine if using the flatwoods would result in significantly better yields.


To learn more about the Soil Science Foundation, please check out the Soil Science Foundation Records at the McKay Archives: https://www.flsouthern.edu/getattachment/96400c75-e443-47c6-9fc7-690feef0137c/Soil-Science-Foundation-Records-Finding-Aid.pdf.

Written by Tanzy Zviitwah, Florida Citrus Hall of Fame Fellow
In partnership with Florida Southern College’s McKay Archives Center
Spring 2024

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Source:
 

Mack, Thomas B. Citrifacts. Bartow, Florida: Associated Publications Corporation, 1992.

From the Archives: Cattle Feed

In the 1900s, growers began to feed cattle the leftover pulp, peels, and seeds that were left behind after the desirable parts of citrus fruit had already been canned for production. Because pulp has a high liquid concentration, it went bad faster than the cattle could eat it. This left much of the feed to rot out in the pastures. This led researchers to run feed tests to determine if the citrus by-products were providing any nutrition for their cattle. This research found that only the pulp had any actual nutritional value that would be beneficial to the cattle while both the peel and seeds did not have any value to them.

Upon this discovery, there was a race to patent citrus pulp as feed. Everyone wanted a chance at reaping the rewards for this invention. The Pratt Food Company was one of the first plants that popped up in Tampa with the sole purpose of processing citrus waste. After this, several other companies opened branches that were responsible for dealing with citrus waste.

In order for the pulp to be fed to the cattle, it had to be dried. Reducing the liquid concentration in the pulp allowed the growers to store the pulp for later use without it going bad due to the liquids being held inside the pulp. There are many advantages to using dried citrus pulp for feed. Citrus pulp is a very bulky carbohydrate meaning cattle do not need to eat a lot of it and pulp is high in calcium. However, pulp is low in phosphorus, one of the major nutrients that cattle need, meaning it must be supplemented with other forms of feed to ensure that cattle stay healthy. Citrus pulp is still being used for feed today; however, it is not used for milking cows as it can cause a decrease in milk production.

Written by Tanzy Zviitwah, Florida Citrus Hall of Fame Fellow
In partnership with Florida Southern College’s McKay Archives Center
Spring 2024

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Source:
 

Mack, Thomas B. Citrifacts. Bartow, Florida: Associated Publications Corporation, 1992.

From the Archives: Big Freeze

During harsh winters, citrus groves will freeze over - killing the trees to the ground. The first big freeze was in 1835, which was extremely discouraging to early growers. One can understand why Central Florida became a hub of citrus production in the United States, with the optimal climate it's a no-brainer! The optimal climate for citrus production is warm areas with ample sunshine, and 55-100 degrees Fahrenheit is the best range for citrus growth. There are few varieties of citrus that are able to grow in colder temperatures below 50 degrees, but even then, they cannot withstand temperatures lower than 45 without freezing.

When a freeze takes place, the fruit will drop from the tree either instantly or slowly over a period of time. The juices inside of the fruit become frozen making them unideal for selling. Crystals of ice will also form inside the plant tissues throughout the actual tree. During severe cases of freeze, the tree may die; in less severe cases, the tree may be damaged, but it will survive. In the years following a freeze, the trees and branches of affected areas may continue to die; it is difficult to determine the extent of damage done to a grove after a freeze has taken place.

After the freeze has taken place, it is important to monitor the state of the grove, especially for later care of the region. There are several tactics that can be used to ensure the plant is able to recover post freeze which include minimizing pruning, applying less fertilizer (depending on the current state of the tree), and minimizing irrigation.

Overall, a freeze can be extremely detrimental to a grower as it can kill the entire grove of current plants. If not killed, affected plants will need additional care in the months and years following a big freeze.

Written by Tanzy Zviitwah, Florida Citrus Hall of Fame Fellow
In partnership with Florida Southern College’s McKay Archives Center
Spring 2024

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Source:
 

Mack, Thomas B. Citrifacts. Bartow, Florida: Associated Publications Corporation, 1992.

From the Archives: Citrus Families and Citrus Labels

Crate labels have a long-standing history in the Florida Citrus Industry illustrating important objects, people or landscapes to the specific brand and grower’s association. This can be seen in many labels that illustrate different family members of Citrus company owners. 

One example of this is the Baby-Ade label. The label features a baby with an orange and a tropical landscape. The baby on the label is a part of the Lee family - the father of Elizabeth Lee Barron. The Baby-Ade brand was a part of the Lee family corporation out of Tampa, Florida. This citrus company grew and processed oranges, grapefruits, and tangerines. Many of the other Lee family members were also featured on their company’s label including Aunt Miriam, Aunt Rosemary, Aunt Rowen Katherine, and even the family dog named Juno, also known as “Goo Goo.” 

Citrus label families have even seen cross over into the Florida Citrus Queen competition. The Prevatt family featured Ruby Prevatt on their Ruby label. The Ruby brand was a part of the Lake Region Packing Association and was owned and operated by the Prevatt family. Ruby Prevatt was a part of the 1939 Florida Citrus Queen competition and was sponsored by the Tavares Woman’s Club. She is also the daughter of Florida Citrus Hall of Fame inductee Jennings Bryant “Babe” Prevatt.

Label advertisement and artwork played a large role in promoting the citrus industry. The ability to implement family members or scenes into the labels allows for a greater connection to customers and the importance of citrus in the family diet. 

All of the labels mentioned above and more can be viewed in the McKay Archives Citrus Label digital collection at https://archives.flsouthern.edu/digital/collection/labels/search/page/1. 

 

Written by Emily Allen, Florida Citrus Hall of Fame Fellow
In partnership with Florida Southern College’s McKay Archives Center
Spring 2024

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Sources:

Calise, Gabrielle. “A Tampa Librarian Wants to Save Florida’s Vanishing Citrus Labels — And Her Family History.” Tampa Bay Times (St. Petersburg, Florida), March 16, 2021. https://www.tampabay.com/life-culture/history/2021/03/16/a-tampa-librarian-wants-to-save-floridas-vanishing-citrus-labels-and-her-family-history/. 

[Miss Ruby Prevatt]. The Orlando Sentinel (Orlando, Florida), January 22, 1939.

From the Archives: Traveling Citrus in Egypt

In 1992, Dr. Prevatt visited the Nile Delta region of Egypt as a citrus expert for six weeks in May and June. During this time, he worked with the Agricultural Cooperative Development International program; the goal of this program was to create a line of dialogue between Egyptian and American farmers and researchers. Prevatt was selected to be the citrus expert because of his background knowledge in citrus. The main objective of his role was to help the growers in the region of interest with any issues they may be facing regarding their crops.
 

Upon arrival, Prevatt was tasked with determining what the major problems in the area were. He concluded that the region was plagued with poor irrigation, Phytophthora foot rot and psorosis were killing trees, lack of a hedging program, excessive use of chemical fertilizers, and closed plantings.
 

At the time, farmers had begun growing citrus in a region referred to as the “New Lands.” This area is made up of sandy desert soils. Other regions where citrus production takes place have silt soil. This means that the same farming practices cannot be used in both regions due to the differences in the soil. Silt soil is a combination of sand and clay. It is an extremely fertile type of soil because it is very good at water retention. Due to the aforementioned fertility of silt, it does not need to be fertilized often. Silt soil is one of the ideal soils for citrus production due to its loose form and drainage properties; Prevatt comments on the effects over-fertilization is having on the crops. For centuries, the Nile River would flood and deposit more silt on its banks. This flooding was later controlled by the production of the Aswan Dam in 1968. Sandy soil is made up of fine particles and is loosely packed. Due to this loose packaging, sandy soil tends to need to be fertilized because it does not hold on to nutrients well. Besides this, it is a good soil for citrus production as long as it is fertilized to ensure there are adequate nutrients present.
 

However, the biggest problem with citrus production in the New Lands is the lack of water. The Egyptian government was attempting to install canals and waterways to aid in agriculture. Due to a lack of funds and resources, the installation of these irrigation systems was not an easy one. Regardless, Dr. Prevatt made attempts to give help where applicable. Dr. Prevatt comments on an interaction he had with a farmer in Cairo. Upon meeting this farmer for what Prevatt thought was the first time, the farmer exclaimed “I know you” to Prevatt. After some discussion, they realized that the farmer had visited Florida Southern College years ago as part of a citrus exchange program. The Agricultural Cooperative Development International program has helped people all over the world and given people the opportunity to visit places they may have never seen.

Written by Tanzy Zviitwah, Florida Citrus Hall of Fame Fellow
In partnership with Florida Southern College’s McKay Archives Center
Spring 2024

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Source:
 
Mack, Thomas B. History of the Citrus Institute, Florida Southern College, 1947-1993. Lakeland, Florida: Florida Southern College, 1993.

From the Archives: Traveling Citrus in China

In 1986, Dr. Prevatt had the opportunity to visit China with 52 students from the Florida State Horticulture Society. During this trip, they experienced both Chinese culture and traditions while having the opportunity to learn about their governmental policy and produce.
 

The first leg of their trip was spent doing tourist-like activities and going to see major historical sites, including the city of Shanghai. Shanghai is a heavily populated city on the port of the Yangtze River, and it runs under an integrated society meaning the government ensures that all its people have work.
 

The group also took a trip to “The Garden City of the World” during this trip, and they were in awe of the artistry that was on display. Prevatt comments on how the people made intricate designs using different plants, rocks and the occasional waterfall.
 

Tourism was not the only goal of this trip; the group moved on to learn more about the various horticulture techniques used in China. Mandarin is the primary citrus grown in China. Most of the land in China has poor drainage meaning the soil does not dry out easily post irrigation. This can be disastrous to produce because it stops plants from being able to take up oxygen through the roots. To combat this, citrus trees are only grown on high beds of land - this helps in making drainage more efficient. Prevatt noted that the Chinese tend to do most farm work by hand with very little machinery to help.
 

This trip was made possible due to the help and cooperation of the U.S. China Exchange Center; they linked the group with a native tour guide to help them get a full experience of the area. Not only were they able to have one-on-one interactions with the farmers, but they also got to see countless historical sites. China is currently the leading producer of citrus in the world making up 28.77% of the world's citrus.

Written by Tanzy Zviitwah, Florida Citrus Hall of Fame Fellow
In partnership with Florida Southern College’s McKay Archives Center
Spring 2024

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Source:
 
Mack, Thomas B. History of the Citrus Institute, Florida Southern College, 1947-1993. Lakeland, Florida: Florida Southern College, 1993.

From the Archives: Citrus Queens and Miss Florida Citrus

The Florida Citrus Queen pageant took place at the Florida Citrus Festival for the first time in 1924, so this year marks 100 years since the start of the competition. However, this first competition had a very different set up compared to the pageants that followed in the years to come.

Young men and women applied to be crowned as the Citrus King and Queen; Polk County residents then had the opportunity to vote for who they thought should be crowned. Both rulers were crowned at that year’s Citrus Festival and were featured as part of the citrus industry parade. Dorothy Williamson was crowned the first Citrus Queen and Harvey Henderson was crowned Citrus King. This was the only time a King would be crowned.

Following the 1924 competition, another queen was not crowned until 1930 when Ruth Snyder became Citrus Queen. However, the competitions that followed were very different from the first one. Women applied to be a part of the contest where they participated in a series of pageant events. The winner was then picked by a panel of judges. This choice was based on their talents, elegance, and philanthropic endeavors.

As the competition continued, the title began to come with numerous responsibilities and tasks. The Citrus Queen was the face of the citrus industry; she made radio, television, and newspaper appearances informing the public about the interests and concerns that the citrus industry had at the time. The competition took a break in the early 2000s and started back up again in 2015. The pageant is still running currently and will soon be celebrating its 100th anniversary at the Miss Florida Citrus Pageant on March 2, 2024.

Written by Tanzy Zviitwah, Florida Citrus Hall of Fame Fellow
In partnership with Florida Southern College’s McKay Archives Center
Spring 2024

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Sources:

Mack, Thomas B. Citrifacts. Bartow, Florida: Associated Publications Corporation, 1992. 

1963 Florida Citrus Queen contestants at the Florida Citrus Exposition in Winter Haven. 1963. State Archives of Florida, Florida Memory. https://www.floridamemory.com/items/show/343554.

From the Archives: Traveling Citrus in Europe

For five weeks in 1982, Professor Mack, along with six students, toured the common markets in Europe. The goal of this adventure was to see firsthand how citrus, among other fruits, was handled and marketed in major importing hubs in Europe. They visited a total of 7 countries including England, Belgium, The Netherlands, Germany, Switzerland, Spain, and France. 

While in England, they had the opportunity to see how apples were grown, produced, and sent out all over the continent. During their 4 week-long road trip across Europe, they spoke with buyers, marketers, and importers of Florida citrus specifically. They had the unique experience of seeing how these markets work behind the scenes. 

The goal of traveling to Spain was to observe the citrus growing styles and the research that was being done on citrus. Today, Spain is the leader in citrus production making up 56% of citrus production in Europe. Spain is well suited for citrus growth for a multitude of reasons, especially the climate as they have hot dry summers. However, this is paired with relatively cold winters, low humidity, and little rainfall, making irrigation a necessity. Although irrigation may be difficult, they are still able to produce large amounts of fresh fruit every year. 

This trip was not only spent learning about produce and how it is grown or marketed. Students had down time to learn more about the cultures and see historical land sites and monuments. In 1983, Mack orchestrated another tour of Europe; however, this one was not nearly as detailed as the tour the year before had been. Both tours gave students memories that most people can only dream of, and the memories they gained will hopefully last a lifetime. 

 

 

Written by Tanzy Zviitwah, Florida Citrus Hall of Fame Fellow
In partnership with Florida Southern College’s McKay Archives Center
Spring 2024

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Sources:
 

Díaz, Sergio. “Citrus Fruit: A Leading Sector Despite the Complicated Context.” CaixaBank Research, October 4, 2022. https://www.caixabankresearch.com/en/sector-analysis/agrifood/citrus-fruit-leading-sector-despite-complicated-context.

 

Mack, Thomas B. History of the Citrus Institute, Florida Southern College, 1947-1993. Lakeland, Florida: Florida Southern College, 1993.

 

From the Archives: Traveling Citrus in Mexico

Dr. Rubert Prevatt and Professor Tom Mack spent a month in Texas in the 1980s. During this time, they crossed the border into Mexico to learn more about one of the world's top citrus producers. The goal of this trip was to observe how they were combating the different obstacles they faced due to the climate in Mexico.  They visited the Campo Agricola Experimental Station where they were able to view all the experiments that were currently being practiced.

The regions where citrus is grown are notoriously arid, extremely dry, and to combat this, they use flood irrigation. This is an extremely wasteful irrigation style as it uses significantly more water than other irrigation methods. During flood irrigation, the land flood gates are opened allowing a large body of water to flow into the area this creates several disadvantages: 80% of the water is being lost as run off or evaporation, all sections of land do not receive the same amounts of water, which may cause anaerobic conditions in the soil. Because the soil is over saturated with water, this can cut off access to oxygen making respiration difficult for plants. Plants are only able to take up oxygen through their roots, but if there is no oxygen in the soil, the plant becomes void of oxygen.

The farmers at Campo Agricola were working on implementing a different irrigation system that would be more cautious of how they used the available resources. Their main focuses were seeing if they could use less water during the flooding and if they could use sprinkling or drip irrigation; as you can imagine, this method uses significantly less water than flood irrigation. With all the issues they face, one would not expect the Mexican citrus industry to be as big as it is. Mack comments on how he foresees the industry continuing to improve as the years pass. Mack was correct in his views, citrus production in Mexico has been steadily increasing over the years. Currently, Mexico produces 7.7% of the world's citrus.

Written by Tanzy Zviitwah, Florida Citrus Hall of Fame Fellow
In partnership with Florida Southern College’s McKay Archives Center
Spring 2024

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Source:

Mack, Thomas B. History of the Citrus Institute, Florida Southern College, 1947-1993. Lakeland, Florida: Florida Southern College, 1993.