A Century of Research with USDA in Miami
|A Century of Research with USDA in Miami|
Abstract. From its beginning as a plant introduction garden on 7 acres of rented land in downtown Miami, through 100 years of research efforts, this USDA-ARS station has persevered and focused on improving tropical horticulture. As South Florida has grown and changed, the needs and desires of the populace for agricultural commodities and ornamentals have kept pace. Originally envisioned as a facility for the importation, testing and distribution of plant material from around the world, this laboratory, since 1972 called the Subtropical Horticulture Research Station,has gradually shifted its focus as well as its location. Now occupying 197 acres of what was previously a bayside army aviation training center named for the first U.S. flier killed in France in World War I, Victor Chapman, the station currently has three missions. As a germplasm repository for numerous tropical species including mango, avocado, lychee, carambola, and sugarcane, one mission is to accumulate a collection of clones useful for breeding new cultivars better adapted to the needs of consumers and the local environment and for distribution to other research institutes. A second focus through much of the last 25 years has been studies on the Caribbean fruit fly, which invaded Florida in 1965 and attacks many fruits, requiring the development of quarantine treatments before susceptible commodities can be marketed outside the state. Coupled with this program has been a unit that has sought to improve the postharvest quality of locally-grown fruits and vegetables. In 1998 a unit associated with the restoration of the Everglades was also established that seeks to accommodate grower concerns into the restored ecosystem. Slated for closure only five years ago after moderate damage from Hurricane Andrew, the SHRS now begins its second century with renewed vigor and challenges for the years ahead.
One such explorer, Walter Swingle, had been developing new citrus varieties at a laboratory in Eustis, FL, for several years and undertook the establishment of a new subtropical laboratory and garden in Miami (Fairchild, 1938). Swingle convinced Henry Flagler, the man who opened South Florida to development when he brought his Florida East Coast Railroad south from Palm Beach, to give the USDA an acre of land along Biscayne Bay to be used for construction of a laboratory to study plant diseases. He also persuaded another historic Miamian, Mary Brickell, to give him six acres across Brickell Avenue from Flagler's plot for use as a plant introduction site (Fig. 1). The Department refused the gifts of land but accepted a lease arrangement in 1898 with Herbert Webber in charge. The history of USDA research in Miami had thus begun.
Much of the succeeding history of the early years of the plant introduction station in Miami has been described in previous papers (Fairchild, 1914, 1915, 1923, 1924, 1934, 1938; Popenoe, 1922). These tell of the work by early plant explorers, such as Fairchild and Wilson Popenoe, who searched the world for agricultural and horticultural crops hoping to diversify the diets and gardens of Americans in general and Floridians in particular. The material that the explorers would import, primarily seeds after recognition that other plant material harbored a greater risk of the introduction of new plant diseases (Pauly, 1996), would be grown, propagated, and distributed by horticulturists such as P. H. Rolfs and Edward Simmonds (Fairchild, 1933). When the facilities on Brickell Avenue proved too small, 25 additional acres of land were leased in 1914 from Charles Deering 7 miles north between NE 21st and 30th Streets on N. Miami Avenue in a section of the city called Buena Vista. It was soon recognized, however, that this property was also insufficient. With his connections in Washington, David Fairchild was able to secure a revocable permit from the War Department on a portion of a large property declared surplus along Biscayne Bay, 15 miles south of Miami and Coconut Grove. The former army air base of 850 acres seemed perfect for his dream of creating an "Ellis Island for plants" - a living collection or arboretum to benefit both teaching and scientific study . As he would continually declare, Fairchild sought "a piece of climate" not simply land, which was plentiful and cheap inland but more prone to cold temperatures. He wanted a place where sensitive tropical plants could be propagated and bred for resistance to colder temperatures prior to their introduction to areas of the U.S. farther north. The Army's Chapman Field Military Reservation was not shielded from the warm Gulf Stream by barrier islands and was one of very few locations thought to be frost-free. On April 26, 1923, the first trees were planted at the new USDA site (Burditt et al, 1973).
The U.S. Army Signal Corps' Cutler Aerial Gunnery Field had been renamed for Victor Emmanuel Chapman, the first American aviator to be killed in France in World War I, on November 15, 1918 (Kleinberg, 1985). Chapman joined the war effort in 1914, before the U.S. became officially involved. From the French Foreign Legion (Fig. 2) he was accepted in April, 1916, as a founding member into the American Escadrille, a famous squadron composed of American pilots fighting for France, more widely known by the name it received later in the war: the Layayette Escadrille. Many of the pilots were recent graduates of Harvard (as was Chapman), Princeton, and other prestigious universities. Although they could be reckless in the air, the shared danger of combat fostered deep loyalties among the fliers. On June 23, 1916, Chapman, off duty, was flying to a field hospital to visit and deliver fruit to an injured member of the squadron when he saw a group of three squadron mates depart on patrol toward the battle at Verdun. Not wanting to pass up an opportunity to engage the enemy, he turned to follow. In a short time the regular patrol crossed into German territory and encountered five German fighters. Outnumbered, the leading group of Americans withdrew to French lines after a brief combat, unaware that Victor Chapman was rushing to their assistance. Chapman found himself alone among the five Germans, and his plane was shot down behind the German lines near the ruins of the French town of Beaumont (Mason, 1964). A body presumed to be that of Victor Chapman was recovered after the war, but dental records didn't match; nevertheless, the body was placed in a grave under his name in the American Cemetery at Suresness. Consequently, the remains in that grave at Suresness were not later removed to a memorial to the Lafayette Escadrille built at Villeneuve Park in St. Cloud outside Paris, and the crypt bearing Chapman's name remains empty (Gordon, 1991).
Soon after leasing a portion of Chapman Field in 1923, USDA horticulturists began propagating their accessions for transfer to the new property (Fig. 3, top), and many of the plants from the Brickell and Buena Vista sites had been transferred to the new Plant Introduction Garden by the time a disastrous hurricane hit Miami in 1926. The period of great plant explorations continued unabated into the 1930's and 1940's; however, the portion of Chapman Field allotted to the USDA amounted only to 160 acres in 1935, and concern continued about running out of space. Fairchild and Robert Montgomery, a neighbor on Old Cutler Road who shared with Fairchild a special concern for plants and the development of a botanical garden in the area, sought to have the entire acreage given to the USDA. Instead, local aviation interests and the War Department continued to use part of the land for training exercises (Fig. 3, bottom), including bombing runs over the bay. One month before the entry of the U.S. into World War II the transfer finally seemed imminent, but this was put on hold over the war years. During those years Fairchild and others continued to send new plant material to this station, and the place was used at times by the military for survival training (U.S. Dept. Agr., 1945; Hodge et al, 1956). From August of 1942, the army air facilities at Chapman Field were made available to the Embry-Riddle Corporation, which was contracted to train civilian and military pilots (Brown, 1994).
Throughout the decades, plant explorations have continued to bring in new specimens for propagation and distribution, but the focus of research has changed over the years. Early introductions sought to improve the diet of Americans, and tropical fruits, including many new cultivars of avocado and mango, were introduced, some of which were well-adapted to southern Florida and became widely planted. Concurrently, flowering and shade trees, including the white geiger, the Hong Kong orchid, the flame-of-the-forest, the African tulip tree, and many Ficus species, and palms were introduced to beautify city streets and gardens. Other introductions, such as a variety of rubber-producing plants (Loomis, 1953), bamboo and medicinals, sought to benefit industry. In the 1950s and into the 1960s, as in the previous decades, this station was closely associated with both agriculture and ornamental horticulture, and new plant introductions, as well as cultivars developed here, were freely distributed to local nurseries and garden clubs (Hodge et al, 1956; Miller, 1956; Shrum, 1959). Research at this station during the third quarter century has been reviewed by Burditt et al (1973).
A departmental reorganization in 1972 renamed the USDA's facility at Chapman Field the Subtropical Horticulture Research Station (SHRS), and research station-wide was administered through the Subtropical Horticulture Research Unit. In the latter part of this decade two horticulturists were employed. Mr. Paul Soderholm continued to evaluate and breed ornamental plants and maintained the germplasm collections. He spent many years breeding new varieties of the ornamental shrub Dombeya, and several selections released into commerce from the station can be seen growing around the Miami area. Mr. Soderholm retired in the early 1980s, and the ornamental program languished thereafter. Maintaining a station of this size with living examples of thousands of plant specimens became increasingly expensive, and ornamental plantings deteriorated as invasive trees and vines spread into plots.
Dr. Robert Knight, Jr., from the 1970s through much of the 1990s, continued the tropical fruit crops program, working with many tropical fruit species. He selected for improved characteristics in avocado, mango, lychee, carambola, and passion fruit. Work with lychee resulted in selections that fruit more consistently and have better fruit quality than commercially grown varieties, and seed he collected in Malaysia gave rise to the ‘Arkin' carambola. His research with hybridization of Passiflora incarnata and P. edulis led to the development of ‘Byron Beauty', an ornamental passion vine for the temperate zone. Other tetraploid hybrids from this work are being tested in Georgia for cold tolerance and maintenance of fruit quality. Dr. Knight also produced Passiflora ‘Incense', a hybrid of P. incarnata and P. cincinnata, which is now planted in parts of the temperate zone in the U.S. and Europe.
With the arrival of Dr. R.J. Schnell in 1987, the direction of plant science research changed. The collections at Chapman Field were formally designated as part of the National Plant Germplasm System (NPGS), and Chapman Field was designated as a National Germplasm Repository (NGR). The NPGS is a collection of USDA research stations around the country with the mission to preserve the biological diversity within agriculturally important plants. The SHRS has responsibility for the maintenance, preservation, characterization, and enhancement of mango, avocado, lychee and longan, annona, carambola, tropical citrus, banana and plantain, and other tropical fruit species. Responsibilities also include maintenance of a world collection of sugarcane and related grasses as well as a large collection of the forage grass Tripsacum.
In 1987 a temporary molecular genetics laboratory was established to aid germplasm research at the same time that a new facility was being planned which would house all plant science investigations. In its state of the art facilities the next year, research progressed at a rapid rate using molecular markers to characterize the germplasm collections. The aim of this research has been to remove duplicate genotypes, to establish estimates of genetic diversity among clones, and to begin to produce genetic linkage maps. Significant progress was made in all these areas.
The NGR-Miami has been important to the cacao industry of Central and South America throughout this period. While the U.S. does not produce any cacao, significant quantities of milk, sugar, peanuts, almonds, and other materials produced in the U.S. go into the making of chocolate products. The station is one of two quarantine facilities for cacao in the western hemisphere that serve to keep diseases from moving into the area. The NGR-Miami has been involved with the genetic analysis of cacao using molecular markers and selection for resistance to the Witches' Broom pathogen. Dr. Cathy Ronning received her Ph.D. based on studies of the molecular genetics of cacao while working at SHRS under the direction of Dr. Schnell. She was the first graduate student to receive a doctorate while working at this location.
On August 23, 1992, Hurricane Andrew passed over the southern tip of the Florida peninsula. The SHRS was in the northern eye-wall of the storm and suffered a significant amount of damage. Assessments made several months after the storm revealed a loss of approximately 30% of the fruit tree and sugarcane germplasm and 50% of the ornamental germplasm. Even with these considerable losses the NGR-Miami was still the largest of the clonal repositories in the U.S. system. Most of the fruit crop and sugarcane germplasm was reintroduced from backup locations, but the ornamental collections were not replaced. This was the first major natural disaster occurring at a field gene bank in the U.S., and it took over two years to fully recover from this storm. At the time of the storm, the staff of the SHRS numbered approximately 36 (Fig. 5).
Citing the costs of restoring the station and its plantings after the hurricane, as well as urban encroachment around the station and into the farming areas that made reestablishment of tropical fruit production questionable, the SHRS was slated for closure by the USDA in 1994. By this time, however, much of the station's reconstruction had been completed, and local agriculture was rebounding. Concern over the loss to tropical agricultural research galvanized the scientific community to support the station. Within the local community, Mr. Frank Smathers, a retired banker and amateur horticulturist, tirelessly lobbied state representatives and Congress to keep the SHRS open. Subsequently, station personnel and representatives from Fairchild Tropical Garden, the National Tropical Botanical Garden, Florida International University, the University of Florida, and the Dade County Parks Department developed an organization plan for a public-private partnership, and from neighborhood and local agricultural and research communities an advocacy group of 2,000 members was formed. A Memorandum of Understanding between ARS and the Friends of Chapman Field recognized the cooperation between the two parties in fostering and publicizing agricultural and horticultural research. In Congress, a House/Senate compromise kept the SHRS open through 1995, at which time a second attempt at closure was defeated by both the House and Senate. No further attempt was made to close the station during this decade; not only was the SHRS preserved, Congress appropriated several million dollars to upgrade the facility.
In 1994 Dr. Knight retired and Dr. Ronning was hired as a Post-Doctoral Research Associate. The molecular genetics work resumed with marker development and genetic fingerprinting for the mango, annona, and the lychee collections. A new molecular technique was developed for the detection of Avocado Sunblotch Viroid that has been accepted as a diagnostic test for the disease by the Departments of Agriculture in both the State of California and the State of Florida.
Another field of plant science research that has been represented at this station for a number of decades concerns the Market Quality of tropical fruits and vegetables. The Department of Agriculture has shown an interest in postharvest quality of tropical fruits since a lab was established in Homestead, Florida, in 1953 (Carmichael, 1955). Initially the Krome Avenue lab, staffed by Drs. T. T. Hatton and John Popenoe, developed maturity standards for avocado and lime, then within two years began studies to improve the market quality of avocado and mango fruits by determining optimal storage and ripening conditions. In 1956 this market quality lab was moved to the Plant Introduction Station in Miami (Burditt et al, 1973), and in 1957 Drs. Aristotle Pappelis and Carl Campbell joined the staff as research plant physiologists. All four men had departed the station before 1971 when Dr. Donald H. Spalding, a research plant pathologist, arrived to study postharvest quality of tropical fruits and vegetables. Through 1987, Dr. Spalding studied methods to improve storage of these commodities and reduce decay and the quality changes induced by quarantine treatments against the Caribbean fruit fly. Among other projects, he tested modified storage atmospheres and low-pressure storage for fruits including mangoes and avocadoes and evaluated the effects of fumigants, irradiation, and heat on mangoes and grapefruit.
This work was continued in 1989 by Dr. Ray McGuire who worked with the entomologists to develop specific quarantine treatments against the fruit fly in grapefruit, navel orange, mango, guava, lychee, and longan, and against weevils and scale insects in sweetpotatoes and limes, respectively. By this time, the most commonly used fumigant, methyl bromide, was being displaced, and heat, cold, or gamma irradiation were the alternatives most generally proposed.
Two other projects of Dr. McGuire included the development of biological control of postharvest grapefruit decay using antagonistic yeasts and postharvest treatments of lychees to maintain color and reduce decay. By re-formulating the coatings applied to grapefruit during postharvest processing, he was able to improve survival of the yeast antagonists whose populations increased in cold storage at the same time that fruit became more susceptible to green mold decay caused by Penicillium digitatum. Two cooperative research and development agreements with private industry resulted from this work. Coatings were also used to influence the surface environment on the lychee pericarp. Because the red anthocyanin pigments in the pericarp are more brilliant under acidic conditions and anthracnose decay is reduced, cellulose and other coating materials were modified to increase the amount of acidity at the fruit surface and also to reduce fruit dehydration, resulting in a longer shelf-life.
A third program area, the entomology section, was established at this Miami research station in 1968 as a result of the establishment in 1965 of the Caribbean fruit fly in Florida. Because the fly would lay its eggs within a wide range of tropical fruit, not only was fruit quality reduced, but quarantine issues also became important when states like California and countries like Japan threatened to embargo fruit suspected of containing a pest that was not already present within their borders. Burditt et al. (1973) gives some of the accomplishments of the early years of this program, which included learning how to rear millions of the flies on artificial diets for experiments on sterilization and other control techniques including trapping and bait attractants. Entomologists who served during this initial period included Fernando Lopez, Loren F. Steiner, and Donald von Windeguth.
During the mid-1970s research shifted to include investigations of quarantine treatments for commodities infested with the Caribbean fruit fly. In addition to von Windeguth, entomologists Clarence Benschoter, Dr. Arthur Burditt, and chemist Dr. Jimmy King conducted work during this period that included the development of ethylene dibromide, methyl bromide and cold as quarantine treatments and the investigation of fumigant residues on treated commodities. Large-scale fumigations were tested in a special facility constructed for this purpose, and many of these fumigation treatments were commercialized to ship Florida grapefruit to Japan. To aid in the development of quarantine treatment methods, USDA-APHIS-PPQ Methods Development assigned a research entomologist, Dr. Peter C. Witherell, to this location.
Through the early and mid-1980s, there was continued work on insect attractants, which included work by Dr. Peter Landolt with the papaya fruit fly, as well as studies on the host status of commodities investigated by Dr. Dennis Howard. In mid-decade research shifted to finding alternatives to ethylene dibromide, which was banned as a carcinogen in 1984 by the U.S. Environmental Protection Agency. One of the treatments developed during this period is the widely-used hot water immersion treatment for mangos developed by Dr. Jennifer Sharp; all mangos entering the United States from foreign countries use some form of this hot water treatment, as do Florida mangoes shipped to parts of the U.S. A cold treatment was developed for carambolas, and a hot water treatment was developed for guavas, by Dr. Walter Gould, which allow these fruit produced in Florida to be exported to large markets in the western U.S. that quarantine the Caribbean fruit fly now endemic in this state. Gamma irradiation was further refined as a treatment for a number of commodities including mangos, citrus and carambolas by von Windeguth. Dr. Guy Hallman investigated insects infesting a number of locally-produced commodities including canistels, black and white sapotes, and spondias, and he sought to refine quarantine treatments by modifying the internal atmospheres of fruits. Much of this quarantine work was subsequently described by Sharp and Hallman (1994).
From the late 1980s through the late 1990s heat treatments were further investigated to include the development, in cooperation with other USDA laboratories, of vapor heat and dry heat treatments. Hot air treatments were developed for citrus, mangos, carambolas, and other commodities by Drs. Gould, Hallman, Sharp, and Jim Hansen. Development of quarantine treatments for additional species of insects attacking subtropical fruits and vegetables was also begun. Heat, cold, or gamma irradiation were tested against sweetpotato weevil, banana moth, plum curculio, blueberry maggot, Diaprepes weevils, mealybugs, and others by Drs. Sharp, Gould, Hallman, and Jim Moss. Whereas the entomologists investigated insect mortality, Dr. McGuire examined quality changes within the various commodities resulting from quarantine treatments. After 1990 Drs. Gould and Mike Hennessey evaluated other fruits for possible removal from a list of hosts for the Caribbean fruit fly. Eventually, limes, lychees, longans, and mamey sapote were determined to be non-hosts, which made quarantine treatment unnecessary and opened new markets in western states for these Florida commodities.
During the period from 1968 to 1986 there were usually three entomologists and a chemist on staff at any given time, but by the late 1980s the number in the entomology program had risen to six scientists. Attrition and threats of station closure after 1994 brought the number down to one entomologist and a chemist at the end of 1998. Increases in tourism and shipments of tropical commodities, however, have continued to threaten American agriculture, especially that in Florida, with the establishment of exotic insect pests. A re-direction of the entomology unit will emphasize work outside the country to prevent the introduction of exotic pests to the United States and place less effort on the development of domestic quarantine treatments.
Until 1997, the entomology section, market quality, and plant science were three separate funding entities within the Subtropical Horticulture Research Unit of SHRS. With Dr. Sharp as Research Leader and Location Coordinator, the station had an annual budget at the time of more than $2,000,000. Market quality research and quarantine research were then incorporated into the Postharvest Quarantine and Quality Research Unit in 1997, with Dr. McGuire as Acting Research Leader, whereas the Subtropical Horticulture Research Unit from that time has focused solely on germplasm research, with Dr. Schnell as Research Leader and Location Coordinator. Also in 1998, the Everglades Agro-Hydrology Research Unit was established under Dr. Reza Savabi to investigate changes to local agriculture that would result from the restoration of a natural flow of water in the Florida Everglades. After 50 years of constructing dikes and canals to channel water away from developed areas and farmland, state and federal government had committed themselves to a restoration of the natural habitat, but this would displace some homeowners and lead to the flooding of many farms. The new unit is charged with understanding hydrologic processes in South Florida to help sustain the local agro-ecosystem and environmental quality; more directly, it seeks to produce maps of possible flooding and develop a model relating hydrology and crop growth in agricultural areas.
Cooperative programs in pest control.
The Animal and Plant Health Inspection Service (APHIS) of the USDA established the Beagle Brigade at SHRS in 1988 after searching for a location for regional training. The dogs are used at Miami's international airport to inspect cargo and passengers for illegally imported agricultural products that may harbor quarantined pests. The program has grown from one to six dog handlers and includes one kennel attendant, although training is now performed at national centers such as one in Orlando.
With offices first established in 1959 (Burditt et al, 1973), the Division of Plant Industry (DPI) of the Florida Department of Agriculture and Consumer Services is the longest-lived tenant at the SHRS. The office inspects and certifies plant nurseries; it also places insect traps within the community to identify new pests and conducts surveys to identify disease outbreaks that threaten the agriculture of Florida. Lou Lodyga is the current supervisor of the region extending from West Palm Beach east and west to the coasts and south to Key West. In 1965 a DPI employee first captured and identified an adult Caribbean fruit fly in Miami, resulting in the ARS quarantine program against this pest. Around this time lethal yellowing disease of coconut and other palms also appeared, and DPI made efforts to control the plant disease. With other strategies failing, an improved breeding program was begun within Florida's Division of Forestry, which established an office at SHRS in the 1980s. Mr. Bill Theobold supervised a program to develop disease resistance by crossing the Malaysian dwarf and the Panama tall palms to produce the resistant Maypan. Many resistant trees from this program were distributed to municipalities to replace street trees killed by the disease. The program ended in 1996.
Asiatic citrus canker, a disease of many citrus species caused by a quarantined bacterium, was discovered near Miami's international airport in October, 1995, and DPI was charged with surveying for the pest and its eradication. Failure to eradicate the disease would eliminate exports of fresh fruit from Florida to important markets such as California and Japan where the disease does not exist. An office at SHRS established in December, 1996, one of four around Miami-Dade and Broward counties, employs 25 people under the supervision of Khalil Abu-Rus to survey from SW 88th Street to SW 296th Street. If surveyors find trees that appear to be infected with citrus canker the suspect trees are rechecked by pathologists, and, if confirmed to be diseased, they are removed.
The threat of exotic diseases and insect pests wreaking havoc with Florida's agriculture has only intensified in recent years. Many new pests, such as the pink hibiscus mealybug, lurk on Caribbean islands waiting for an opportunity to invade. In the early years of this century it was fairly easy for men like David Fairchild and Wilson Popenoe to introduce new plant species to augment the diets and gardens of Floridians, but the Plant Introduction Station at Chapman Field provided a controlled environment prior to a general release to the public. Plant introduction and improvement continues at the SHRS, but our mandate to the public now also includes an analysis of the repercussions to the local ecosystem and research that promotes active exclusion of exotic pests in interstate and international commerce. After 100 years serving the needs of Florida growers and consumers, the USDA-ARS in Miami is poised to begin a new century of agricultural research.
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Unless otherwise mentioned, figures are property of the U. S. Department of Agriculture and from the archives of the Subtropical Horticulture Research Station, Miami, Florida.