History of International Nurseries
In the 1950s a stem rust epidemic attacked wheat in the USA and Canada. About 60% of the wheat harvest in the US was destroyed in 1953, and about 75% in 1954. The culprit was a new pathogenic race called 15B, which was resistant to all genes present in existing commercial varieties. A similar race spread widely in Latin America. In response to the epidemic, the US Department of Agriculture requested that seven nations (Mexico, Colombia, Ecuador, Peru, Chile, Argentina, and Canada) join forces in testing 1000 lines selected from the wheat world collection.

The Office for Special Studies, CIMMYT's predecessor, was an active participant in the effort, and new lines of wheat were exposed to  stem rust in Mexico. The results of the First International Stem Rust Trial exceeded all expectations. New sources of resistance were found for the 15B race, some of which may still be present in commercial varieties today. An added benefit of this trial was the creation of a network through which lines and introductions could be tested and distributed to developing countries.

In 1960 the first international spring wheat yield nursery was distributed by the Office for Special Studies to 12 countries from Canada to Argentina. In response to the expressed interest of other wheat-producing countries around the world, in 1964 CIMMYT created the International Spring Wheat Yield Nursery (ISWYN) that included lines adapted to high and low latitudes.

In 2001, the International Wheat Improvement Network (IWIN) at CIMMYT prepared 2,766 sets of 40 different bread wheat, durum wheat, triticale, and barley nurseries. Seed shipments were sent to a network of 619 wheat scientists from 117 countries around the world.

Purpose and Objectives of IWIN
The International Wheat Improvement Network acts like a diplomatic corp for the CIMMYT Wheat Program. IWIN is the annual contact point between the CIMMYT Wheat Program and a global network of wheat research cooperators who evaluate wheat, triticale, and barley germplasm. CIMMYT's improved germplasm is dispatched, through nurseries targeted to specific agro-ecological environments, to this network of researchers. Data from these trials are then returned to CIMMYT, catalogued, analyzed and made available to the global wheat improvement community. The ultimate beneficiaries of the fruits of this network are farmers who will receive improved bread wheat, durum wheat, triticale, and barley varieties.

Calendar of Seed Preparation and Distribution at IWIN

June, Year 1. Seed is planted in El Batan. Field plots are repeatedly treated with systemic fungicides, and harvested seed is disinfected with a sodium hypochlorite solution. Seed from each line is inspected by CIMMYT's Seed Health Unit (SHU) and approved for quarantine multiplication in Mexicali.

July, Year 1. Nursery request forms are sent to IWIN cooperators. The global distribution list is finalized in January, Year 2.

November, Year 1. Seed is sent by air from El Batan for quarantine multiplication in Mexicali. Mexicali is recognized by the Mexican Government (NOM-001-FITO-1995), the North American Plant Protection Organization (NAPPO), and the European Plant Protection Organization (EPPO) as a Karnal bunt-free area. Mexicali field plots are repeatedly treated with systemic fungicides, visually inspected, and sampled for more diagnostic pathogen testing.

June-December, Year 2. Mexicali seed is harvested and returned to El Batan in sealed trucks. Internal seed from each line (>5,000 lines) is inspected by the SHU. Seed health certification is required before seed is cleaned, washed, treated, dried, and packaged.

IWIN seed preparation methodology:

• Seed is washed with detergent and high pressure water for 2 minutes.

• It is then rinsed with a pressure hose for 6 minutes.

• The seed is submerged in a "jacuzzi bath" of 1.2% sodium hypochlorite solution for 3 minutes, and rinsed with high pressure water. Excess moisture is removed with compressed air.

• The seed is covered with a mixture of fungicides and placed in an oven to dry at 28-30^o C for 1.5 hours.

• Dry seed samples are placed in new bags and stored in a sterile room.

• As trials are prepared, envelopes are filled with the appropriate seed and arranged in boxes.

• Field books, a phytosanitary certificate, and appropriate paperwork are included in each box.

January-December, Year 3. Nursery shipments are dispatched by express air couriers, or air freight, to cooperators in more than 120 countries.

January­December, Year 4. Data are returned to CIMMYT-Mexico by IWIN cooperators, entered into the IWIS database, analyzed, and returned to cooperators on CD-ROM. They can also be made available in real time via web access (pending future application).

Role of the Seed Health Unit in IWIN
CIMMYT's Seed Health Unit (SHU) certifies all wheat, triticale, and barley germplasm to be exported by CIMMYT in international nurseries based on: 1) field inspection of the nurseries during the growing cycle, 2) multiple greenhouse and laboratory tests on harvested seed, and 3) seed washing and application of chemical treatment to the seed before shipping.

All IWIN shipments are accompanied by 1) a CIMMYT health certificate issued by the SHU, 2) an international phytosanitary certificate issued by the Government of Mexico, and 3) a declaration of value.

Facts and Figures

Role of IWIS in IWIN
The International Wheat Information System manages and integrates diverse information pertaining to bread wheat, durum wheat, triticale, and barley. IWIS provides each line with a unique identifier. Using the IWIS identifier, scientists can pinpoint a particular line despite its numerous names, trace its family tree, and explore what is known about it.

IWIS allows researchers to:

• Search and download data using quick, user-friendly options;

• Gather information from genebanks, laboratories, and field tests and apply it to plant breeding;

• Through the unique identifier, trace the ancestry of individual lines and estimate the degree of relatedness among them;

• Update family trees as ancestry data become available.

The immediate beneficiaries of IWIS are scientists in NARSs and other institutions who can access information needed for breeding and other research activities.

IWIS is accessible on-line through the CIMMYT-Mexico LAN and via periodic CD-ROM publications. Web access capabilities is planned for the near future.

IWIN Trials Available from CIMMYT

The following IWIN trials are currently available for distribution to collaborators globally from CIMMYT-Mexico.

August, 2004