Bananas are widely enjoyed on Japanese tables. In the Philippines, which imports most of these bananas, diseases such as leaf blight and plant wilt are becoming increasingly serious. The discovery by a Japanese researcher contributed greatly to the establishment of a method to control the disease, and we will introduce the efforts of international joint research between Japan and the Philippines, which, with the support of JICA and other organizations, is striving to prevent the disease from spreading beyond national borders.
Professor Kyoko Watanabe (left) and Researcher Shunsuke Nozawa. in the banana test greenhouse on the Tamagawa University campus.
What is the project that even the Philippine Ambassador to Japan has high expectations for?
In March 2026, Philippine Ambassador Extraordinary and Plenipotentiary to Japan Milene Garcia-Albano was present at an international symposium held on the campus of Tamagawa University in Machida City, Tokyo. During the symposium, participants discussed the results and future prospects of the banana and cacao disease research jointly conducted by Japan and the Philippines.
Ambassador Albano expressed his expectations to the researchers and ministry officials from both countries, saying, “The results of this project will contribute greatly to the establishment of science-based, long-term solutions to diseases that threaten industries of great economic and social significance to our country,” to which the audience responded with applause.
Philippine Ambassador Albano speaks at the International Symposium
Challenges faced by banana-loving Japanese
Japan is a nation of banana lovers, with each household consuming about 18 kilograms per year. Bananas are grown in the tropics, and imports amount to about 1 million tons per year, of which about 80% comes from the Philippines.
In 2005, a large-scale disease was identified in the Philippines. A vicious cycle ensued, as no method was found to identify and control the pathogen, allowing it to persist in the soil, leading to the abandonment of cultivated land.
So far, about 18,000 hectares of the 80,000 hectares under cultivation have been abandoned. Identification of the pathogen and establishment of a new pest control method had become an urgent issue for Japan, which “relies on the Philippines. In banana cultivation, pesticide application has been the subject of social criticism, and a new control method was sought for leaf blight, the main target of pesticide application.
This is why we launched this international joint research project.
Disease-stricken banana leaves
I looked it up… actually different disease-causing bacteria.
There’s something distinctive about the shape.”
In 2024, in a laboratory at Tamagawa University. Shunsuke Nozawa, a specially-appointed assistant professor (at that time, now a researcher at Fukushima International Research and Education Organization), was examining banana pathogens brought back from the Philippines under a microscope when he felt something strange. At first, the disease that killed banana leaves was thought to be “black sigatoka disease,” and Mr. Nozawa brought the fungus back mainly to study black sigatoka disease.
In addition to cultivating the fungus and analyzing its DNA, Nozawa continued his steady research by planting the fungus on healthy plants to check for pathogenicity. One day, he noticed the characteristic shape of the fungus. In the case of black sigatoka disease, the causal agent, Pseudocercospora sp. looks like a white line. However, the spores of the fungus seen under the microscope were “shaped like a black manjuu” (Nozawa).
It was a completely different fungus called “Nigrospora sp.”, a group of bacteria that also includes pathogens that kill rice and other crops. The study revealed that not only the previously recognized Pseudocercospora sp. but also other pathogens that had not been expected may have been involved in the reason why the pesticides used by the local farmers were not very effective.
Mr. Nozawa recalls, “The leaf blight was more complicated than expected, and while I felt sorry for the farmers, the discovery of the causative fungus was a big step forward.
Mr. Nozawa answers an interview
Nigrospora sp. identified by Nozawa as a major cause of banana disease
What is JICA and JST’s international joint research?
This research is being conducted within the framework of the “SATREPS” program, an international science and technology cooperation program to address global-scale issues provided by JICA and the Japan Science and Technology Agency (JST).
This is an international joint research project in which Japan and research institutes and ministries in developing countries are working together to address global-scale issues that are difficult for a single country to solve, such as climate change, food problems, and natural disasters. The goal is to create new knowledge based on local needs, and to contribute to problem solving and sustainable development through social implementation of research results.
JST will support the research expenses required in Japan, and JICA will support the research expenses and equipment required in the partner country. This is a cooperative framework that benefits both parties: for Japanese research institutions, it has the advantage of being able to conduct research in fields that meet the challenges of developing countries, and for developing countries, it leads to the resolution of social issues by improving research capabilities, fostering human resources, and utilizing research results. Since its inception in 2008, more than 200 projects have been implemented in over 60 countries in Asia, Africa, Latin America, and other regions.
Yohei Hashimoto, Director of JICA’s Economic Development Division, explains the significance of JICA’s involvement in SATREPS as follows.
JICA has the advantage of being able to link Japan’s domestic research resources with local development issues. JICA’s role is to invest in areas that the private sector cannot touch, in anticipation of future benefits.
Toward Social Implementation of New Pest Control Methods
Professor Watanabe being interviewed with a banana in his hand
This project is called “BaCaDM (Project for the Development of Novel Disease Management Systems for Banana and Cacao),” which aims to prevent diseases of banana and cacao. Tamagawa University and Central Luzon State University in the Philippines have signed an agreement to collaborate in 2021.
For the Philippines, where banana is a major industry representing the country, identifying the cause of the disease and establishing a method to control it has been a longstanding issue. If a control method can be identified through joint research, a recovery in production can be expected, and this will directly lead to an improvement in the standard of living of farmers. Furthermore, if the control method can be applied to other producing countries besides the Philippines, it will lead to solutions to the “global-scale issues” that SATREPS has set forth.
The project is currently in the process of selecting new pesticides that will be effective against the disease. Furthermore, the “soil reduction disinfection method” using low-concentration ethanol spraying, which has been established in Japan, has been found to be effective against wilt, a disease that causes banana plants to wilt.
Professor Kyoko Watanabe of Tamagawa University’s Faculty of Agriculture, who oversees the project, says, “At first, we had to cut all bananas in a 10 meter square for the soil reduction disinfection method, but now we know that we can do it one at a time. Since fewer trees need to be cut, the hurdle for local farmers will be lowered.
Although BaCaDM will end in 2026, Professor Watanabe says that he will continue to support local researchers to conduct long-term research until the new pest control method is widely adopted by farmers. The main local researcher will be Dr. Selin Ocampo-Padilla, who received her doctorate from Tamagawa University.
Human resource exchange and development, and building trusting relationships are also major achievements.
Selin (left) reporting research results to cacao farmers.
Dr. Serin, who is the head of the Plant Pest Control Research Center at Central Luzon State University, originally studied plant pathology, but this project brought him to Tamagawa University, where he studied for three years and served as a leader in research on cacao disease control. She says that her future goals became clear as she continued her research while traveling back and forth between Tamagawa University and Central Luzon State University.
Accuracy is important in both experiments and data analysis, and I have acquired the skills to achieve this on my own. From now on, I would like to work as a person who can strengthen disease management, especially for high value-added plants such as cacao, and give back what I have learned in Japan to farmers, colleagues, and students.”
The year 2026 marks the 70th anniversary of the establishment of diplomatic relations between Japan and the Philippines. The fact that young researchers from both countries, represented by Mr. Nozawa, 33, and Ms. Serin, 39, were able to cross the border was a major feature of the project, further strengthening the ties between the two countries, which have enjoyed friendly relations for more than half a century.
SATREPS has the potential to build a long-term relationship of trust between Japan and other countries.
© Source JICA