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What is IOCV?


IOCV Foundation

by James Merril Wallace
(original text provided by Jane Wallace)

The International Organization of Citrus Virologists

As information on the ravages of tristeza in South America and California reached other citrus growing-countries, it was recognized generally by citricultural scientists and growers that this disease posed a serious threat to citrus throughout the world. That brought many foreign government officials, scientists, and growers to the Riverside Citrus Experiment Station to learn about this problem and measures to be taken against it. Contacts with these individuals and with others during my travel in Mediterranean countries in 1954 and 1955 as well as the many inquiries that came by mail made it evident to me that some type of international organization was needed to disseminate information and encourage research on tristeza and other virus diseases of citrus. An opportunity to form such an organization came in 1957 on the occasion of the fiftieth anniversary of the Citrus Experiment Station. A local committee was appointed to plan special programs during that anniversary year. I was not a member of that committee but was invited in April to meet with them and discuss the desirability of planning a one-day program devoted to the station’s work on citrus virus diseases. At that meeting, I suggested an international conference, and having given considerable thought to that need, I was able to present a good case for it. My suggestion was received favorably, and I was asked to work out details for such a conference and present them a week later for committee action.

The next days were spent discussing this matter with colleagues who were engaged in one way or another in the study of citrus virus diseases and at another meeting with the university committee. I presented details for a conference to be held in November. With authorization to proceed, I formed an organizing committee, outlined procedures, and established priorities and a time schedule for the many things to be done. Because of the limited time to develop the conference, it was decided to have invitational papers only. That permitted us to select the subjects and speakers and to send special invitations to the latter to assist them in obtaining financial support from their institutions. With help from the campus public relations officer, Howard Cook, and long hours of efficient secretarial work by Mrs. Darlene Franke, a series of announcements were sent to about 300 individuals in the United States and foreign countries. This included scientists, citrus growers, nurserymen, and others with professional interest in citriculture. As registration forms were being received, members of the organizing committee worked on the many details that had to be considered. The conference opened on November 18 with more than 200 registered delegates. The majority of these were Californians, but there were large delegations from Arizona, Texas, and Florida. Twelve foreign countries were represented by twenty-one delegates. Thirty invitational papers were presented during formal sessions, and field trips were taken to the Coachella Valley and citrus areas of Ventura and Santa Barbara counties. At a business meeting, I proposed formation of a permanent international organization and presented my ideas regarding the need for it. That met with a favorable response, and, after much discussion, the delegates voted to form such an organization, which would meet at three-year intervals. At that point, Dr. T. J. Grant from the USDA Orlando, Florida Horticultural Field Station, moved that Dr. Wallace be acclaimed president or chairman of the proposed organization with power to select a name for it, appoint committees, and take other actions necessary to establish a permanent group or society with membership open to anyone working with or interested in citrus virus diseases.

Having spent the past six months planning for the Riverside conference, I was somewhat reluctant to accept the responsibility of developing the newly formed organization but agreed to do so because of my appreciation of the need to put citrus virus disease research on an international level. Thus, the International Organization of Citrus Virologists, IOCV, was born in November 1957. During the first three formative years, more than 200 individuals registered membership. The only formal office was that of chairman, and there were no dues. Committees proposed and appointed by me as chairman were:


  1. Time and place for next conference;
  2. Indexing procedures, diagnosis, and nomenclature of citrus virus diseases;
  3. Rootstocks and nuclear clones;
  4. Bibliography of citrus virus disease literature;
  5. Liaison with other plant scientific societies;
  6. Publication of proceedings;
  7. Membership and financing.

Inasmuch as the IOCV was founded at that time, the Riverside meeting was considered to be the first conference of the organization. Proceedings were published by the University of California in a volume titled Citrus Virus Diseases. Containing thirty-five papers, this quite well brought together in a single volume all that was known about citrus virus diseases in 1957. By 1960, when a second conference was held in Florida, committees had begun functioning and the new organization drew 97 delegates representing sixteen different countries. Fortyseven papers were presented and published in the proceedings. The fact that these largely reported new research findings was proof of the impact our new organization had brought to the study of citrus virus diseases. Additionally, the second successful conference established IOCV as a permanent organization with an important role to play in citrus growing-countries. That it was accomplishing its objectives became more and more evident as subsequent years’ conferences were held in Brazil, Italy, Japan, Swaziland, Greece, and Australia. Besides providing for formal reports on research studies and firsthand field and laboratory observations in the host countries, preconference and/or postconference tours permitted travel to neighboring countries. For example, the conference in Italy in 1966 was followed by visits to southern France, Corsica, Spain, and Morocco, and that in Japan in 1969 included a postconference tour to Taiwan, Hong Kong, and the Philippines. Recognizing the international standing of IOCV, countries hosting conferences spared no efforts to provide well-planned formal programs, excursions for field study, and enjoyable nonscientific activities for visiting delegates.

Further evidence of the impact IOCV has had on citrus virus disease research is the fact that following the sixth conference, a total of 346 research papers were published in the conference proceedings. Prior to 1957, no citrus virus had been isolated or mechanically transmitted. By 1975, several viruses had been isolated and characterized, and herbaceous hosts of some had been discovered. Discovery that the causal agent of citrus exocortis disease, having no characteristic protein coat, is a newly discovered disease-causing agent, a socalled viroid, may be of great significance in determining the cause of some diseases of both plants and animals as well as the control of these diseases. Another outstanding research development has been the discovery that stubborn disease is caused by a mycloplasma that infects numerous herbaceous hosts and is transmitted by several species of leafhoppers. The stubborn organism can be grown on artificial media. IOCV members have been responsible for development of much of the present knowledge on plant disease mycoplasmas. The cause of the disastrous citrus disease known as “greening” has been determined to be caused by an organism much like that causing stubborn disease but not a true mycoplasma.

In addition to these and other important developments in this field attributable to the existence of IOCV, this organization has been responsible for development of strong programs of research in all countries where citrus is an important crop. IOCV has sponsored the printing of a citrus virus disease bibliography containing more than 2,000 abstracts of publications that is being kept up to date. An outstanding accomplishment has been the preparation and duplication of an extensive collection of color slides of citrus virus and virus-like disorders. These can be removed for projection and a text covering pertinent information accompanies each group of slides. The first edition of 300 copies was disposed of immediately, and a second revised edition was printed. The accomplishments of this relatively small international organization have far exceeded the dreams I had for it. Not the least of the dividends it has paid are the closer friendships formed between individuals attending conferences and the opportunities it has provided for travel. The host countries have arranged pleasant social affairs and tours that gave visiting delegates an opportunity to experience the customs and way of life of their people. Extensive postconference tours to other countries added to those experiences. These extras have made IOCV conferences family affairs in that many delegates are accompanied regularly by members of their families. In my experience, no other international organization can boast of the closeness and camaraderie found in IOCV. It is my hope that it will continue to find strong leadership, not only to continue to solve citrus disease problems but to continue to bring together people of different cultures and philosophies and encourage in its small way understanding and goodwill among men.



(by Chet Roistacher)

These are times of great and important changes in citrus virus, viroid and procaryote diseases, considering their ability for rapid dissemination by man and vector with many new developments in research, diagnosis and control. New diseases are continually appearing and some are extremely devastating i.e. citrus sudden death in Brazil which has killed over 4 million trees in a very short period of time. Currently, a new form of huanglongbing (ex-greening disease) is spreading rapidly in Brazil. Its vector Diaphorina citri is now present in Mexico, Florida and Texas and threatens to spread to many countries of Central America and the Caribbean islands. The witches' broom disease of limes has destroyed the lime industry in Oman and is devastating the small fruited lime industries in the United Arab Emirates and in Iran. Citrus variegated chlorosis in Brazil and Argentina is a very serious problem and appears to be spreading into Central America. The costs of controlling the citrus leprosis disease can limit citrus production in many areas and leprosis now appears well established in Central America. Citrus chlorotic dwarf in Turkey is the first whitefly transmitted disease of citrus. There are more than 10 totally new diseases of citrus which have appeared throughout the world in recent years. New severe stem pitting strains of tristeza are spreading and huanglongbing continues to limit the life of citrus trees to 5 to 8 years in many countries of Asia. Citrus blight is spreading and taking a severe toll of citrus in many countries and its cause is still unknown. The brown citrus aphid `Toxoptera citricida' is now present in perhaps all of the islands of the Caribbean, in many countries of Central America, in Mexico, Florida, Texas and the Madeira islands. With increased air travel this primary vector of CTV may eventually find its way into all citrus producing countries. It's presence in the Madeira Islands has caused severe destruction of the citrus there and the BrCA is now present in northern Portugal and Spain. With its entry, all trees on the sour orange rootstock may be killed as has been its history in the past. New and severe tristeza outbreaks are now occurring in Italy and in Greece.

The IOCV is the one organization dedicated to the study and control of diseases of citrus by personal contact, publications, international cooperation and the dissemination of knowledge in the fight against citrus virus and virus like diseases. In addition to the 15 proceedings of IOCV plus periodic newsletters, there are books and handbooks available through IOCV in cooperation with FAO such as "Virus and virus like diseases of citrus in the Near East" by J.M. Bove; a "Handbook for detection and diagnosis of graft transmissible diseases of citrus" and a " Historical Review of the Major Graft transmissible Diseases of Citrus" both by C. N. Roistacher. Also, in 2000, the American Phytopathological Society has edited a revised version of "Compendium of Citrus Diseases", with the contribution of many IOCV members. The Sociedad Española de Fitopatología has published a monograph in Spanish "Enfermedades de los Cítricos". The or websites contain not only some of the previously mentioned books, but is a vast resource containing over half a million literature citations, over 40,000 color slides in JPG or GIF format, and a glossary of over 30,000 terms. On this website there are now over 125 slide shows and over 50 of these slide shows are on various citrus virus and virus-like diseases. These slides or slide shows can readily be downloaded and are being translated into French, Spanish and Portuguese. Now, a new website for IOCV is being launched through the courtesy of I.V.I.A., Spain that, in addition to general information on IOCV and its newsletters and proceedings, will contain a revised version of the IOCV Color Handbook of Virus and Virus-like Diseases of Citrus.

And finally, there is available "Citrus Health Management" - L. W. Timmer & L. W. Duncan, Editors - (1999) - 223 pp paperback, 64 color plates - Designed to aid in developing a successful plant health program, with special emphasis on current Integrated Pest Management practices. Management practices cover not only the interrelationship between plant, pathogen and the environment, but also describe several economic and environmental issues related to citrus health. This combination creates a holistic treatment of citrus health management. Following the detailed management methods explained in Citrus Health Management will help produce healthy and profitable citrus crops.

IOCV is a unique organization and we welcome your membership and participation!


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