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Fusarium wilt of banana in the Philippines: incidence, distribution and cultivar response

Fe Delacueva: University of the Philippines Los Banos

<div><em>Fusarium oxysporum </em>f. sp. <em>cubense </em>(Foc) has been causing epidemics on Cavendish plantations since 1974 in the Philippines. In 2000, a more severe and aggressive epidemic was observed which was caused by the more virulent Foc strain, the VCG 1213/16, known as Tropical Race 4 (FocTR4). Since then thousands of hectares of Cavendish plantations were destroyed by FocTR4. There is also a concern that this virulent race may affect the important local cultivars grown for the local markets in the country. A survey was carried out to determine the distribution of various Foc strains in the country, with emphasis on TR4. A total of 134 isolates were collected from 21 provinces of Luzon, Visayas and Mindanao. Foc isolates were characterized through PCR analysis using race-specific primers and analysis of vegetative compatibility groups (VCG). Results showed that Fusarium wilt is present in almost all areas surveyed but FocTR4 was detected only in Mindanao, where Cavendish bananas are grown. High incidence of Fusarium wilt was noted in <em>Latundan, Saba and Lagkitan</em> cultivars, but isolates from these varieties belong to Race 1 (VCG 0122 and 0123). Results of pathogenicity tests and field evaluation showed that three important local cultivars, namely <em>Saba</em> (AAA), <em>Latundan</em> (AAB) and Lagkitan (ABB) were all susceptible to Race 1 but resistant to FocTR4. Gran Naine (AAA) was resistant to Race 1 strains but susceptible to VC1213/16, the TR4 strain. Differential cultivar response to the different VCGs suggests the existence of interaction between Foc races and banana cultivars.</div>