Food and Fertilizer Technology Center - publications

Dec. 24, 2009

Establishment of Pathogen-Free Citrus Germplasm Repository for the Improvement of the Citrus Industry in the Aspac (Year 3)

Citrus greening disease (Huanglongbing or HLB) and other virus diseases such as citrus tristeza closterovirus (CTV), citrus tatter leaf cappilovirus (CTLV) and citrus exocortis viroid (CEVd) have been causing considerable damage to fruit yield and quality, and have become serious constraints for the citrus industry in the Asian and Pacific (ASPAC) region in recent decades. These systemic diseases are effectively controlled by integrated measures of disease management such as: 1) establishment of virus-free citrus cultivar repository, which is of primary importance in preventing prevalence of the diseases; 2) precise and rapid disease indexing techniques indispensable for management of pathogen-free (PF) nursery system through health certificate of PF seedlings; 3) establishment of shoot-tip micrografting technique for obtaining PF germplasm foundation; and 4) performance of health management for preventing reinfection of PF trees in the field through IPM of vector insects. These integrated techniques have been well-developed and adopted for the improvement and development of the citrus industry in Taiwan. Hence, citrus growing countries in the ASPAC look forward to Taiwan's technological support to prevent growers' losses due to citrus greening and other virus diseases.

Under this three-year special project, to rehabilitate the citrus industry in ASPAC countries, an advanced Taiwanese technology package will be transferred first to Cambodia, and then to other countries in the region. The technology package shall include establishment and application of pathogen-free citrus foundation, and disease-indexing technique for controlling serious epidemic of citrus greening (HLB) and other virus diseases. Specifically, the project shall have the following activities:

  • 1) Survey of citrus greening and virus disease incidence in ASPAC countries;
  • 2) Conduct of technical consultation among growers on health management in the citrus-growing areas of the region;
  • 3) Training-workshop on virus indexing and shoot-tip micrografting technology;
  • 4) Collection and virus-elimination of the most important citrus cultivars (more than 15) selected from participating countries in the region for the establishment of pathogen-free citrus germplasm repositories to be made available to every country as a way of promoting promote regional technical cooperation; and
  • 5) Establishment and management of pathogen-free citrus nursery system in the ASPAC region.

Highlights of Year 3 Implementation

On the final-year implementation of this three-year project which aims to rehabilitate the citrus industry particularly in Cambodia, the first Phytopathology Laboratory was established in the country's Royal University of Agriculture (RUA). The facility is expected to intensify RUA's research capacity to fight the devastating citrus greening (HLB) and other citrus virus diseases and to train young scientists in the areas of disease indexing, production of virus-free nursery foundation, and healthy management to prevent re-infection. RUA has also completed construction of a net-house for virus-free repository and disease-free nursery production. Under the coordination and expertise of Dr. Hong-Ji Su, NTU Professor Emeritus and FFTC consultant, trainings on shoot-tip micro-grafting technology for virus-free germplasm foundation and propagation/cultivation of disease-free seedlings were also conducted during the three-year project implementation.

Also under the project, Dr. H.J. Su was invited to give lectures and presentations in a variety of international conferences/seminars/workshops to widely disseminate advanced and practical technologies on HLB management. Some of these events include: the international seminar on "Influence of Global Climate Change on the Diseases and Insects in Citrus" held in Jeju, Korea; the USDA-ARS' International Research Conference on HLB, as a keynote speaker on Research and healthy management of citrus HLB in Taiwan; technical guidance on Improvement of antibiotic injection technique for chemotherapy of HLB at Kasetsart University, Thailand; and lecture on Epidemic, detection and health management of citrus HLB (greening) and CTV disease for citrus rehabilitation at the Department of Agriculture, Thailand. In addition, the project team also visited other Asian countries namely the Philippines, Malaysia and Vietnam to conduct surveys of citrus orchards for HLB infection, as well as to provide on-site and laboratory trainings.

In 2008, the Asia-Pacific Association of Agricultural Research Institutions (APAARI/FAO), in cooperation with the Asia-Pacific Association on Agricultural Biotechnology (APCoAB), also supported the publication of a booklet entitled Production and cultivation of virus-free citrus saplings for citrus rehabilitation in Taiwan written by Dr. H.J. Su. The booklet is now widely used as a technical guide in the management and control of HLB by the various stakeholders of the citrus industry in the ASPAC.

As a concluding activity, FFTC Director Dr. Jen-Chyuan Lee, joined by Dr. Fu-Hsiung Lin of the Rural Development Foundation (RDF), Taiwan ROC and Dr. H.J. Su, visited Cambodia primarily to assess the project's impact and achievements in the last three years. They had an observation tour of the Phytopathology Laboratory of RUA, established through a series of technical and financial support and instrument donation under the project. The team also visited a field demonstration of pathogen-free (PF) citrus seedlings being managed by RUA in cooperation with the Ministry of Agriculture of Cambodia. The field demonstration is envisioned to promote the use of PF-seedlings among farmers and growers by showcasing the superiority of such planting materials in terms of fruit quality and yield.

Establishment of Pathogen-free Citrus

Germplasm Repository for the Improvement

of the Citrus Industry in ASPAC (Year 3)

This three-year (2006-2008) project was carried out in Taiwan ROC, Cambodia, and other ASPAC countries.

Cooperating organizations: Royal University of Agriculture (RUA), Cambodia; National Taiwan University (NTU)

Sponsor: Rural Development Foundation (RDF), Taiwan ROC

For further information, contact:

Dr. Hong-Ji Su, FFTC Technical Consultant

Index of Images

  • ac2008l1.jpg

    Figure 1 (Left) Mr. Vung Setha of RUA gives an orientation-briefing of the new RUA citrus net-house to FFTC Director Dr. J.C. Lee, Dr. H.J. Su and Dr. F.H. Lin (from rigth to left). (Above) Visit to the RUA Phytopathology Laboratory established through the project's technical and financial support.

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