Dr. Georgios Vidalakis

: Professor & UC Extension Specialist in Plant Pathology

: Department of Plant Pathology & Microbiology University of California, Riverside

Dr. Vidalakis completed his undergraduate studies in 1998 at the Agricultural University of Athens, Greece with concentration in plant protection and environment and specialization in plant virology. He became the director of Citrus Clonal Protection Program (CCPP) in the summer of 2005 a year after earning his Ph.D. from the Department of Plant Pathology at the University of California, Riverside, where he was the recipient of the Special Dean’s Fellowship Award for the duration of his doctoral studies. Funded by the Citrus Research Board, California Citrus Nursery Board, California Department Food and Agriculture, and the United States Department of Agriculture, Dr. Vidalakis has developed a diverse research and extension program that is serving all citrus producing states in the US via the citrus germplasm services of the National Clean Plant Network (NCPN) for specialty crops and the CCPP.

As an Extension Specialist Dr. Vidalakis has been working directly with the citrus industry, growers and nurseries, at a state and national level. His service to the citrus industry include, but is not limited to, the organization of industry supported events (e.g. Meeting the Challenge of the Asian Citrus Psyllid in Nurseries), participation in key industry organizations and committees (e.g. Citrus Research Board Committees) as well as state and national panels and workgroups (e.g. Recovery Plans for the National Plant Disease Recovery System).

As a researcher, Dr. Vidalakis has developed a program focused on the study of graft-transmissible pathogens of citrus with emphasis on viruses, viroids, and bacteria. Mixed viral infection and their effect to biodiagnosis of citrus diseases as well as the biological activity, molecular properties and intrapopulation structure of citrus viroids have been part of his work. He is also focusing on citrus diseases, such as Huanglongbing (HLB), and citrus associated microbes and their potential beneficial impacts on citrus production as well as the optimization of the functions of citrus germplasm programs, which include: diagnostics (bioindexing and laboratory), therapy (shoot tip grafting and thermotherapy), production, and distribution of citrus propagative materials (foundation blocks and variety management).

Dr. Vidalakis is also participating in several national and international programs. He is one of the founding members and the Chair of the NCPN-Citrus and he is a member of the Laboratory Accreditation Board STAR-D of the USDA National Plant Diagnostic Network (NPDN). He is a member of the Viroid Study Group of the International Committee on Taxonomy of Viruses (ICTV) and the 2019 Chair Elect of the International Organization of Citrus Virologists (IOCV), while he just completed a 10 year tenure as the Secretary of IOCV.

Dr. Graham H. Barry

: XLnT Citrus


Dr. Graham Barry has been involved in the South African Citrus Industry for the past 27 years, and is now the owner of XLnT Citrus, a company focusing on the development and implementation of novel and innovative citrus products and services, and provides independent technical and strategic consultation services to stakeholders in the Citrus Industry.

Graham attended the Univer­sity of Natal, South Africa, where he obtained a BSc(Agric) degree in 1987. After working as an Extension Officer for the South African Co-operative Citrus Exchange in Paarl from 1990 to 1991, Graham was transferred to Outspan Citrus Centre in Nelspruit where he provided direction and leadership to the South African citrus cultivar development programme, including the identification, global sourcing, importation, and evaluation of new citrus cultivars to meet export market requirements. In the process he developed a rapid cultivar introduction system, thereby reducing the period of introduction and evaluation of new citrus cultivars in South Africa to less than four years (from import to fruiting). He also developed planting guidelines for citrus producers throughout Southern Africa to optimize production of high quality export fruit based on market prospects, production trends, and climatic suitability of cultivars to production regions. In 1995, Graham completed his MSc(Agric) thesis at the University of Natal on cross-pollination of Citrus spp., and thereafter studied at the University of Florida (USA) towards his PhD dissertation on factors affecting citrus fruit quality which he obtained in 2000. From 2001 to 2007 Graham was seconded by Citrus Research International to the Department of Horticultural Science, University of Stellenbosch, where he provided research leadership to CRI’s Crop Load and Fruit Quality Management programme, and conducted applied research on citrus fruit quality enhancement with emphasis on rind colour, sugar accumulation and acid metabolism resulting in the graduation of five MSc(Agric) students over a period of five years.

During the past 16 years, Graham has dedicated much of his time to citrus cultivar development for private enterprise, the South African citrus industry and for a private Spanish company where he lead the development of a state-of-the-art private citrus breeding, introduction and evaluation company, providing strategic direction to plan and implement the project.

Ian S. Tolley, OAM

: Managing Director, Tolley’s Nurseries Pty. Ltd

: Tolley’s Nurseries Pty. Ltd.

Ian Tolley is an internationally recognised specialist in nursery production technology and orchard planning and management. Early professional training in Civil Engineering and Surveying provided a sound base for consultancy planning.
A horticultural generalist, he offers an intensive, practical approach to both orchard and nursery, together with a broad-scale overview.

Ian initiated and developed the micro-budding technique of citrus, and he led the container-growing of citrus under cover, both techniques widely adopted around the world.
He has produced of a constant stream of inventions relating to orchards and nurseries, and is widely recognised for his applied irrigation and general technological innovation, together with introduction of new mechanisation to orchards and nurseries.

Recognised by the international horticultural industry as a leading practitioner, Ian has been involved in orchard management and consultancy in Australia over the past 60 years. He has promoted economic adoption of high density horticultural crops, and for over 40 years urged recognition of a need for a new conservation strategy for water managementTolley’s Nurseries Pty. Ltd. consultancies with individual growers and consortiums, in orchards and nurseries include USA (Florida & California), South Africa, Fiji, Indonesia, Malaysian States, including Terengganu. Over several years Ian acted as Lead Consultant UN – FAO Citrus Rehabilitation in SE Asia, in association with GTZ (International German Aid Group) in the planning to restructure the citrus industries of Thailand and Egypt.

  1. Awarded one of the initial Churchill Fellowships, he has continued to travel widely, studying world citrus and nursery production techniques.
    1995. Awarded an Order of Australia Medal for services to community, horticulture, and the citrus industry in particular.
    1999. Received the prestigious IPPS International Award of Honour, the first given outside USA.

World-wide contacts are ongoing in exchanges of propagation technical information, & friendships.

A lecturer on production and technical aspects of horticulture, Ian is a regular ABC Commentator on horticulture and gardening. A prolific writer, he shared authorship of the SA Botanical Garden Handbook “Citrus for Everyone” 1999, & a revised edition in 2009. In 2007 he acted as technical advisor to “Outstanding in their Field- 50 years of Riverland Field & Gadget Days” by Noelle Tolley & Mark Thomson. Ian’s major work of “Commonsense Citrus” was published in May 2017. □ 

Klaus Bederski

: The Topara Fruit Tree Nursery

A graduate in Pomology,   University of California, Davis in 1959 with a Masters Degree in Citriculture, University of Florida, Gainesville in 1960, Klaus returned to Peru and has been involved in fruit growing activities ever since. He was asked to initiate and manage a fruit tree nursery specializing in citrus in 1962. The venture was successful until it was expropiated during a Land Reform law in the 1970´s. By that time, Klaus had acquaired land of his own for the purpose of establishing pecan orchards and starting a new fruit tree nursery.

Topara Farms in 2017 grows, processes and exports pecans, avocados and Capsicum varieties to U.S. and German markets under a family business scheme now directed by his son Stefan. The Topara Fruit Tree Nursery provides true-to-type trees whose vigour and root systems are appreciated by growers. Topara Farms, nursery included, are certified organic since 2001. Becoming organic has been one of his greatest challenges and has also been one of his most rewarding experiences.

Klaus has been a member of, and has participated in all congresses of ISCN since 1985. He also participates in congresses of IOCV, ISC, World Avocado Society.

Paul Fourie

: (Plant Pathology and Genetics

: Southern African Citrus Improvement Scheme (SACIS)

After obtaining a B.Sc.Agric. (Plant Pathology and Genetics) at University of the Orange Free State, Bloemfontein, Paul Fourie obtained BSc.Hons., MSc.Agric and PhD(Agric) degrees in Plant Pathology from Stellenbosch University in South Africa. He started his professional career as a grapevine pathologist, and from 2007 as a citrus pathologist. He is currently the manager of the Southern African Citrus Improvement Scheme (SACIS) at Citrus Research International (CRI), the research and technology service provider to the southern African citrus industry. The SACIS is the primary citrus propagation material source in Southern Africa and >80% of SA’s rootstock seed and >95% of budwood is supplied from its Citrus Foundation Block outside Uitenhage in the Eastern Cape province to certified nurseries and growers. As plant pathology researcher he is associated with Stellenbosch University’s Plant Pathology department as extraordinary professor. His research focuses on fungicide application technology in citrus orchards and packhouses and Citrus Black Spot epidemiology. He has been directly involved in the student training of 7 PhD students and 22 Masters students, his scientific outputs include 69 scientific articles, 93 international and 134 national congress presentations. Paul resides on the Citrus Foundation Block farm with his wife Sonja and two daughters, Emma and Kara. Between work and school, the Fourie’s enjoy the great outdoors and the ocean as much as possible.

Graeme Sanderson

: Research Horticulturist

: NSW Department of Primary Industries, Dareton

Graeme Sanderson entered employment with NSW Department of Primary Industries in 1977 which has involved research nursery propagation of a range of agricultural crops.
In 1996 he began his current role of horticultural evaluation of local Australian citrus mutations and new citrus variety introductions to Australia. Graeme currently leads the ‘National evaluation of new citrus varieties’ project funded by Horticulture Innovation Australia (HIA).

His team is undertaking the independent horticultural evaluation of the majority of new citrus introductions to Australia with new varieties added to the program as they exit Australian Plant Quarantine. The aim of the work is to rapidly propagate and independently evaluate their horticultural performance under Australian growing conditions.

Tim Herrmann

: Manager

: Auscitrus, Dareton NSW, Australia.

Tim was born and raised a fourth generation mixed horticulture farmer in South Australia’s Riverland. After completing a Bachelor of Applied Science in Agriculture (Horticulture) he started work at the Loxton Research Station as a nurseryman/technical assistant before moving on to manage the Plant Quarantine Station nursery in Adelaide, then on to other private sector nursery and irrigated horticulture employment.

In 2004 Tim took on the position as Manager of Auscitrus, the Australian citrus seed and budwood scheme. Tim was given the task of moving the scheme from its long established location on a NSW DPI Research station, to a new facility on a greenfield site owned and operated by Auscitrus, where he is still employed as Manager.

Roger Smith

: General Manager

: TreeSource Citrus Nursery

Roger Smith is the founder and General Manager of TreeSource Citrus Nursery in Woodlake, California.
He is a 4
th generation citrus farmer that joined the citrus nursery profession in 1988 where he worked for Michaelis Nursery.
He was hired to build TreeSource in 1998 and the company has grown to be one of the largest propagators of citrus in the U.S. with propagations of 1.1 million trees annually.

TreeSource grew container and Field Grown trees until 2013 when the operation moved all trees into Insect Resistant Screenhouses and greenhouses. TreeSource has a reputation of innovation and has brought many new technologies and concepts into the citrus nursery business such as automation, citrus liners, under canopy irrigation, systems for dense plant production, growing environment optimization, and much more.
Roger has been a member of ISCN since 1991 and served as Secretary-Treasurer from 2005-2014 and in now serving President-elect.

Dr Tahir Khurshid

Dr Tahir Khurshid is a citrus plant physiologist and has leaded several projects in Australia and overseas. Dr Khurshid mainly works with rootstock evaluation program at Dareton and has 18 years’ experience in this field.  Recently Dr Khurshid has released 6 rootstocks for the Australian citrus industry.  Dr Khurshid has worked for 10 years in overseas projects funded by the Australian Aid program.  The program included nursery development, irrigation management and crop management and to build the capacity of scientists, extension officers and growers in Pakistan.

Dr Khurshid is also an expert in citrus phenology, crop regulation, canopy management and heat unit mapping.  Dr Khurshid has been involved in advising and making recommendation for the specific varieties based in regional climatic conditions using Heat/Chill Unit Mapping expertise.  Dr Khurshid is a national authority on citrus flowering work and also provide national consultancy on heat unit work in a range of fruit crops.  Dr Khurshid has published a range of articles in refereed and industry journals and speaks regularly in national and international conferences, field days and workshops.  Dr Khurshid is a visiting professor at the Maejo University Chiang Mai, Thailand.


Nathan Hancock

: Citrus Quality and Market Information Manager

: Citrus Australia

Nathan Hancock is the Citrus Quality and Market Information Manager for Citrus Australia, the Industry Representative Body for citrus in Australia. Nathan has worked in the horticulture industry for 17 years and the citrus industry for the past 10 years beginning in Western Australia where he was the industry development officer for the Department of Agriculture and Food Western Australia.

In his six years with Citrus Australia Nathan has been instrumental in the adoption of new maturity and quality standards in the national industry and has been the driver behind improved industry statistics including the citrus tree census, national plantings database, production forecast model and the online export application system.

Horacio Mederos Acosta

: Translator-Interpreter

Horacio Mederos Acosta is a Cuban citizen born in June 1959, that holds a Bachelor degree in English language (Translation and Interpretation) granted by the Foreign Language College of Havana’s University in 1983.

After graduation, Horacio incorporated to the Citrus Experiment Station of Jagüey Grande, Matanzas province, Cuba, as Translator-Interpreter and Science Assistant which made possible his specialization in agricultural terminology, mainly that of citrus and other fruit crops.

In 1994, he was elected member of the Secretariat of Information and Communication of the Inter American Citrus Network (IACNET), a technical collaboration network from the FAO whose General coordination has been in Cuba since then.

His link to this network for 26 years, has contributed to his participation in workshops, round tables, congresses and events in general, sponsored by IACNET, both in Cuba and abroad.

In his curriculum vitae there are 12 publications, 13 postgraduate courses on Linguistics, Translation and Citrus; the participation in 85 national and international events related to citrus, either as member of the Organizing Committee and Translator-Interpreter.

His contact with the International Society of Citrus Nurserymen (ISCN) was in 2014, when the X Congress of this Society was held in Mazatlan, Mexico.


Christiano CESAR Dibbern GRAF.

: CITROGRAF Citrus Nursery , RBC- Royal Buds Cítricos Brazil

Agronomist and nurseryman, Owner of Citrograf Mudas, company with 50 years producing seedlings (citrus plants) in the state of São Paulo and Bahia. In their four nurseries, can produce more than 1.5 million plants a year. 
First Protected Nursery in Brazil (1997) and the only one with ISO 9001-2015 Certification. General Director of RBC – Royal Buds Citricos, company responsible for export, import and development of new varieties.

Erick Valle

: Production Manager

I have been working in the green industry since 1992. Graduated from Cal Poly Pomona with a degree in Horticulture with an emphasis in nursery management. While attending college, I worked at the Horticulture unit were my passion for plants begin.
I learned to grow different plants while attending there and this eventually lead to an opportunity to work in a nursery growing palm trees. After, growing palms trees for a few years, I decided to try to learn other crops that were a little more challenging such as poinsettia, tulips, anthuriums, bromeliads, and other tropical foliage plants. I have been growing citrus for about 4 years and it has been a fun and challenging crop to grow.
My other passions besides plants are running and hiking.