Pomelo Diplomacy

Through the pomelo, the quintessential Thai fruit, the U.S. and Thailand recently celebrated almost two centuries of collaboration.


In 2023 the United States and Thailand celebrated 190 years of fruitful ties.

Life in the Foreign Service offers numerous challenges, and it is the job of the diplomat to turn the challenge into an opportunity. My challenge was to identify a contribution from the Animal and Plant Health Inspection Service (APHIS) appropriate to the celebration of this diplomatic benchmark.

The foundation of almost two centuries of collaboration and cooperation with Thailand was built through the 1833 Treaty of Amity and Commerce. With this treaty, Thailand became the first country in Asia to establish diplomatic relations with the United States.

Over the ensuing years, the two nations worked together on numerous fronts, such as collaboration during World War II (which continues today); safeguarding of the health of U.S., Thai, and international communities through medical research, innovation, and public health initiatives; promotion of sustainable resource management; conservation of biodiversity; and economic collaboration.

The United States is Thailand’s largest export market. Trade ranges from consumer goods and agricultural products to cooperation with defense industries, which has spurred collaboration in fields outside the economic realm, including security and space technology.

Later, defense pacts established a useful military cooperation, and these promises were upheld throughout the Cold War. When terrorism emerged as a global threat, we supported each other; when global pandemics surfaced, our bonds were tighter than ever in sharing vaccines and keeping safe and resilient trade moving between both nations.

What could I add to this story?

The author (third from right) with Director General of the Thai Department of Agriculture Khun Rapibhat Chandarasrivongs (third from left) and other Thai dignitaries, at the airport, prior to exporting the irradiated fruit, where a ceremony was planned to commemorate the first shipment of Thai pomelo fruit to the U.S.
Jitlada Vasuvat

Pomelo Diplomacy!

I thought about the unique talents of APHIS. For those who don’t know, we are the smallest Foreign Service agency, but our impact is at the heart of most agriculture trade issues.

The APHIS Foreign Service, called “International Services,” is the platform by which APHIS delivers technical talent to support international agricultural diplomacy. We actively back and cultivate the capacity of communities, institutions, and governments to manage threats to agriculture in a way that is sustainable, effective, and protects plants, animals, and the finely interwoven global agricultural community.

International Services encompasses a range of technical experts in entomology, plant pathology, animal health, aquaculture, and risk management, ultimately creating a forum that leverages expertise across APHIS. Through collaboration with foreign counterparts at diplomatic, policy, and technical levels, APHIS promotes science-based regulatory transparency that leads to safe and resilient agricultural trade.

Thailand became the first country in Asia to establish diplomatic relations with the United States.

Suddenly, inspiration struck! Pomelo diplomacy! In 2022, fresh Thai pomelo, the “king of citrus fruits,” completed the necessary regulatory steps and became the eighth Thai fruit cleared for entry to the U.S. The result of more than 15 years of collaborative work between Thai and American agricultural scientists, it is a unique example of the mutual benefits of the U.S.-Thai 190-year relationship.

The eight fruits approved under the preclearance program between Thailand and the U.S. include the mango, longan, lychee, mangosteen, rambutan, pineapple, dragon fruit, and now the pomelo. Unfortunately, when the process concluded in early 2022, the news was swallowed up in the fog of the COVID-19 pandemic. With supply chains strained and many times not working, inflation pushed prices for shipping fresh fruit sky high. No fresh fruit was making the journey to the U.S. from Thailand. My idea was to rally around the pomelo, the quintessential Thai fruit, to cut through the fog to celebrate the 190 years of U.S.-Thai collaboration.

For the 2023 celebration the Thai government planned a July 4 event on the National Mall in Washington, D.C., where the king of citrus fruit would be featured.

How It Worked

The author (center) with the inspection team, at the irradiation facility verifying the pallet configuration and insect proof boxing before it enters the irradiation chamber.
Jitlada Vasuvat

Pomelos, Latin name Citrus maxima, are grown in large quantities in Thailand and native to southeast Asia, where they are also known as sum-oh. The pomelo can grow as large as two pounds and is an original nonhybrid citrus now used to cultivate other varieties of fruit. For example, the grapefruit is a cross of a pomelo and a sweet orange.

Thailand is a major exporter of pomelo fruit, with most going to neighboring countries and China. My goal was to make the U.S. the next recipient of this truly magnificent fruit. As in many places I have worked, I had to start at the beginning: What does that mean? Market access request, pest list development, pest risk analysis, risk mitigation options, rulemaking, all of which can take time. All of this was done, and it was not a small task. The next step would be putting all the pieces together and offering a hand of friendship to Thailand with encouragement and commitment to help make it a reality.

In APHIS we work on both the animal and plant kingdoms, so I got to work with our agricultural scientist and veterinarian Dr. Jitlada Vasuvat (Dr. Mai). Our Thai counterparts at the Thai Department of Agriculture were led by Khun Rapibhat Chandarasrivongs, the director general. I have worked with Dr. Rapibhat for more than 15 years, and we were both familiar with the numerous steps to safely export pomelos: surveilling plant pests, pest trapping, and ultimately certifying the phytosanitary integrity of shipments exported to the U.S. The special ingredient in this process is the use of ionizing radiation. Yes, atomic energy—this was rocket science!

We want to make sure that insect pests of economic significance do not travel with the fruit to the U.S. and reproduce, insects that could cause serious harm to U.S. agriculture (like the Mediterranean fruit fly has been doing in Florida since 1929).

Employing a peaceful use of nuclear energy developed more than 60 years ago, this elegant technique, called the sterile insect technique (SIT), is among the most environment-friendly insect pest control methods ever developed. Irradiation is used to sterilize mass-reared insects so while they remain sexually competitive, they cannot produce offspring. Once the target pest is sterilized, sterile males are systematically released by air over infested areas, where they mate with wild females resulting in no offspring and a declining pest population.

So, if you can irradiate insects for large-scale pest suppression, you can use irradiation as a treatment for trading agricultural products. By using an effective dose of radiation to target pests of concern, you can render any pests sterile and nonreproductive. APHIS advocates the use and application of irradiation as the most effective phytosanitary treatment method. I have had the opportunity of establishing and expanding irradiation programs in Mexico, India, South Africa, Vietnam, and Thailand.

Use of irradiation technology is becoming increasingly important today because methyl bromide, an ozone-depleting fumigant still widely used as a quarantine and preshipment treatment for quarantine pests, is known to contribute to climate change.

The July 4 Event

Thai pomelo, “the king of citrus fruits,” is carefully configured in insect-proof boxes to ensure each fruit receives the proper dose of radiation to sterilize target insect pests.
Jitlada Vasuvat

For the July 4 celebration of pomelo diplomacy and 190 years of U.S.-Thai relations, there was much to do. With only weeks until the event in the U.S., we got to work. Fortunately, Thailand had been using an irradiation facility for other fruits over the years, and that would be our base of operations where we inspected the fruit and treated it in carefully arranged pallet configurations that ensure full dosage is delivered to each fruit. This is tedious, methodical work but so critical in ensuring safe trade and program integrity.

Khun Rapibhat at the Department of Agriculture gave his full cooperation and attention to make this happen and get the fruit halfway across the globe in time for July 4. We just about completed all the technical requirements; on the other side were the logistics: the fruit was flying first class and leaving the Bangkok airport the night of June 27. Khun Rapibhat indicated there would be a small ceremony at the airport to commemorate such an auspicious event.

We started early that day, receiving boxes of fruit from approved packhouses to the irradiation facility, sampling and inspecting fruit for pests, configuring the boxes on pallets, and trying to stay cool in the sweltering irradiation facility. Pallet after pallet going into the totes and whisked behind the thick concrete walls on the conveyer, irradiated, and then right out for loading on the truck for the journey to the airport.

It was a journey I would take the next day with my family, heading to the U.S. for a much-needed home leave. Khun Rapibhat knew I was leaving the next day for home and wanted to make sure I was there for the special event—an event I had no idea would be so special. He mobilized his staff and pulled together an amazing venue, with mascots, lots of fruit, a ribbon cutting, and many heartfelt words khob khun khrup and kha (“thank you” in Thai).

When all was done, the crowd had left, and the smoke settled, my amazing staff of three—Dr. Mai, Kannika Teeraakaravipas (Khun Ju), and Ronnapat Benjakunasatapawn (Khun Pat)—turned to me and said, “You need to pack!”

The United States is Thailand’s largest export market.

As I headed back to Bangkok on that warm night, my excitement mounted with the thought of home. In the Foreign Service you are separated from so much, and soon I would see my mom. The next day we went to the airport to make a similar journey the pomelos had embarked on a few hours before. Flying across the Pacific Ocean to San Francisco, I thought of all the voyages across this massive blue expanse that forged 190 years of U.S.-Thai diplomatic relations that so many have taken for two centuries, each trip bringing us a better understanding of each other.

I would like to think I did my part in these efforts, even if it wasn’t a treaty, or a silk robe, or a gold scabbard. Perhaps it was actually a bit more, because the pomelo represents the journey that the U.S. and Thailand have taken together. The pomelo looks and feels like a globe, and when you next hold one in the palm of your hand, think of all the journeys that have taken place and the story that will unfold for the next two centuries.

Marc Gilkey is a Senior Foreign Service officer who has served with the USDA’s Animal and Plant Health Inspection Service (APHIS) for 30 years. He is currently posted in Bangkok, where he serves as the regional manager for South Asia. He has served previously in Afghanistan, Mexico, India, Belgium, and Colombia, in addition to assignments in Washington, D.C., with USAID. He is a U.S. Navy veteran. He wrote for the FSJ in 2019 on avocado diplomacy in Colombia and in 2022 reflected on agricultural work in Afghanistan.


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