Plant disease can wipe out local banana industry

A plant disease that can wipe out the country’s banana industry is here.

It is named Panama wilt, also known as Fusarium wilt of banana.

Caused by a fungal pathogen called Fusarium oxysporum f. sp. Cubense (FOC), the disease was responsible for wiping out Gros Michel banana, the commercial variety previously grown in plantations in Central America.

Gros Michel is a sweet banana with thick skin that is less prone to bruising during transport.

“It was the variety of choice for the production of export banana in the 1920s to 1950s and made the Central American region the top banana-producing areas in the world at that time,” recalled Dr. Agustin Molina, senior scientist and regional coordinator for Asia-Pacific of the Bioversity International, one of the 15 centers of the Consultative Group on International Agricultural Research (CGIAR).

Disaster struck when Panama disease attacked Gros Michel banana plantations in the mid-1950s.

Within a few years, wholesale destruction was seen in plantations in Central America with 50,000 hectares lost in Honduras alone, Dr. Molina reported at a recent science symposium sponsored by the Department of Agriculture-Bureau of Agricultural Research (DA-BAR).

Dr. Molina, a former University of the Philippines Los Baños (UPLB) vice chancellor for research and extension, added that this destruction drove the banana business to near bankruptcy, prompting the industry to turn to the more resistant Cavendish.

The Cavendish-based industry in Central America, including the Philippines, thrived against this disease. However, a virulent strain of Panama wilt that can attack the Cavendish was found in Asia in the 1990s.

The virulent form of the disease is known as ‘Tropical Race 4’ (TRA), which destroyed banana plantations in Indonesia and Malaysia in the early 1990s, making the Philippines the only major banana exporter in Asia.

“While there have been reports of Fusarium wilt in the country in the 1970s, the threat was not deemed to be on the same level of virulence as those of the neighboring countries, therefore were treated as isolated cases,” recalled Dr. Molina, as reported by DA-BAR’s Vic Guiam.

However, in 2005, reports of increasing susceptibility to and speed of spread of Panama disease among Cavendish banana plantations in Mindanao, particularly in and around the district of Davao City, escalated and could no longer be ignored.

The question thus arose: “Could this more aggressive Foc be the dreaded TR4?”

Thus, samples of the pathogen were sent to the Forestry and Agricultural Biotechnology Institute of the University of Pretoria in South Africa for testing using the vegetative compatibility group (VCG) protocol, the most reliable test for Fusarium pathogen.

“Results of the test showed that the characteristics of Foc from the infested samples were indeed those of Tropical Race 4,” reported Dr. Molina, who is also the coordinator of the Banana Asia Pacific Network (BAPNET).

“Tropical Race 4 affecting Cavendish in the Philippines is a recent development,” pointed out Dr. Molina, as quoted by Guiam. TR4 can affect banana varieties unaffected by other Foc races.

In 1967, TR4 surfaced in Taiwan. By 1990s, it had ravaged Cavendish plantations in Indonesia, Malaysia, and Taiwan, and it continues to spread throughout Southeast Asia and in mainland China. Last year, TR4 was reported to have affected more than 60,000 hectares of Cavendish plantations in South China.

A February 2007 article in a BAR publication, titled “BAPNET” 2007: On the trail of an elusive killer,” discussed this then-unconfirmed threat to the Philippine Cavendish-based banana expert industry.

Dr. Molina explained that the Foc fungus is soil-borne and remains in the soil for decades.

“It is efficiently spread through water and irrigation systems should well avoid the use of infected water or water that runs through infected areas. Infection of the plant is through injured roots,” he said.

Symptoms of the disease may include small bunches, thin pseudostems, and poorly-filled fingers with typical yellowing and wilting of the leaves. They eventually die a few months after getting infected,” Dr. Molina stressed.

He further stated: “Of immense importance is its ability to infest the Cavendish type banana (AAA) of which the Philippines has a number of important cultivars that include the Bungulan and Tumok. The AAB type, which also has a number of local cultivars that include Latundan, is said to be also susceptible.”

In 2006, the Philippines was acknowledged as the second largest Cavendish banana exporter with 2.04 million metric tons produced for the international market. Banana remains as the country’s biggest expert-earning among horticultural crops.

Dr. Molina averred that the banana industry’s loss will greatly affect the national economy. Furthermore, the livelihoods of many small-scale banana producers that supply the local market are also at risk, as many of the country’s important banana cultivars are known to be susceptible to Tropical Race 4.

In the face of grave threats posed by Panama disease on the country’s banana industry, he recommended a “swift and broad survey and characterization of the pathogen’s distribution in the country in order to effect a national quarantine and eradication program to prevent further spread of the disease.”

Options include development of quarantine policies, validation and development of disease management tactics and strategies, and establishment of regional and international Foc collection for basic research such as molecular biology and breeding for resistance.

“The country is hard-pressed to contain the spread of the disease,” Dr. Molina concluded.