International Society for Infectious Diseases
Source: The Business Mirror [edited]
The dreaded Panama disease may have already ravaged more than a quarter of all the banana plantations in Mindanao. Areas infected may have doubled from 15 000 hectares identified by the Department of Agriculture (DA) in 2015, said Victor S Mercado Jr, Marsman-Drysdale Agribusiness Group. The spread was "expected" due to the lack of appropriate biosafety measures in small plantations [that] account for almost half of the total 88 667 hectares planted with the Cavendish variety. Mercado also said "numerous holes" in banana plantations were observed during a helicopter sortie: "This is a likely indication of how the disease has crept through banana areas."
Alberto Paterno F Bacani, Unifrutti Philippines, said, "We have made progress in recovering some of our areas affected, some 218 hectares, by planting them with the resistant variety [GCTCV] 218." He said the fruits were small compared to the regular Cavendish variety that the Philippines exports. He said customers in these markets should be educated about this variety [and] small banana growers should be told that the size and quality of the resistant varieties could still be improved if they will observe good agricultural practices. [He] said government is crucial to help planters prevent the spread of the disease.
[byline: Manuel Cayon]
[Panama disease of banana (PD, also called fungal or fusarium wilt) is caused by the soilborne fungus _Fusarium oxysporum_ (previously f. sp. _cubense_). Symptoms include yellowing, wilting and streaking of pseudostems; affected plants die rapidly. The pathogen is spread by infected planting material, mechanical means (including human and insect activities), soil and water.
Disease management for PD is difficult and mostly relies on phytosanitation for pathogen exclusion. The fungus can survive in the soil for decades, and consequently crop rotation with non-hosts is not likely to control the disease effectively. No effective chemical or cultural control measures are available. Integrated approaches have been developed (for example, ProMED-mail post 20090419.1483), which may include cultural practices, certified clean planting material and biocontrol agents such as _Trichoderma_ species (for example, ProMED-mail post 20160317.4102576 and see link below). Breeding programmes and molecular techniques are being used to develop crop cultivars with increased resistance or tolerance to the different fungal strains. Constant vigilance is required in areas where the fungus is present to prevent flare-ups and recognise emerging new strains.
Several races of the pathogen exist, varying in host range. Cavendish banana varieties (_Musa_ AAA, see links below) replaced the original eating varieties (such as Gros Michel) because they are resistant to the original fungal strain. They include most of the current commercial eating bananas. Cavendish-affecting strains, such as temperate (subtropical) and tropical races 4, as well as a new strain of race 1 (ProMED-mail post 20101223.4510), have emerged since from Asia and Oceania. In recent years, tropical race 4 (TR4) has been reported in the Middle East, Africa, Asia, and, most recently, from the Americas (ProMED-mail post 20190820.6630576). It is of great concern worldwide, so that FAO (Food & Agricultural Organisation of the United Nations) has now launched an emergency project to combat TR4 (see link below).
Development of TR4 resistant cultivars has become a top priority for many national banana industries. [GCTCV] 218 is a spontaneous mutation from a 'Giant Cavendish' (subgroup of _Musa_ AAA) tissue culture clone ('somaclonal variation'), first noticed by a Taiwanese farmer to be resistant to TR4 in his field. Its TR4 resistance mechanism was reported to be based on an up‐regulation of cell wall-strengthening genes in the roots (see link below). However, it has been said to have some differences in taste and shape of the fruit compared to previous Cavendish varieties, and thus there still appears to be an issue with market acceptability.
In the Philippines, PD was 1st reported in 1920 from northern and central areas. It was confirmed in commercial Cavendish in the mid 1970s in southern Mindanao which probably indicates the arrival of TR4 (see ProMED-mail post 20111014.3072). _Musa_ crops in the country are also affected by the viral bunchy top disease (e.g. ProMED-mail post 20191215.6842101) and, nationwide, even more plants are thought to be lost to that than to TR4 (ProMED-mail post 20191015.6727045).
Philippines (with provinces):
PD symptoms on banana:
_F. o._ f. sp. _cubense_ culture:
Information on Panama disease:
Information on race TR4:
FAO emergency project for TR4:
Information on [GCTCV] 218 and TR4 host resistance:
http://www.promusa.org/Pei+Chiao (parent Giant Cavendish clone),
_F. oxysporum_ taxonomy and synonyms:
Information on _Trichoderma_ species and use as biocontrol agents:
Cultivars and hybrids of banana and plantain: