Evaluation of Sigatoka and Fusarium wilt resistant hybrids and cultivars in Tonga and Queensland

• Ministry of Agriculture and Forestry, Tonga
• Queensland Department of Primary Industries, Australia

The project aims to enable new hybrids, bred for disease resistance at the world's leading breeding programs, and under-utilised disease resistant land races of Musa, to be tested for reaction to two serious diseases of banana at trial sites in Queensland and Tonga. Information from Queensland will give valuable information on the behaviour of the germplasm to Fusarium wilt race 4, which currently threatens the Australian banana industry. The information from Tonga would enable the germplasm to be evaluated for resistance to black leaf streak/black Sigatoka disease, which is a major factor limiting banana production in Pacific nations. The potentially disease-resistant germplasm would be available to Queensland and Tonga for further evaluation following this project.

Significant progress was made in preparation for the International Musa Testing Program (IMTP) field trials. Three evaluation sites were established. One to evaluate for Black Sigatoka resistance located in Vaine Research Station, Tonga and 2 located in Wamuran and Cudgen, Australia to evaluate for Fusarium resistance. All germplasm to be tested had previously been virus indexed. In Tonga the required accessions were sent by the INIBAP Transit Center following the Safe Musa Germplasm Movement rules established by FAO/IPGRI and INIBAP. Black Sigatoka trials, which included 12 different banana genotypes, were planted in October 1995 after a 3 month period of acclimatisation. Results showed that 2 genotypes did not show symptoms (Calcutta and Pisang lilin), and another 5 varieties appeared to be highly resistant, with the remaining 5 being susceptible or highly susceptible. The information from these trials will be used by the Australian banana industry to prevent the southern movement (airborne spores) of Black Sigatoka. A biological barrier will be established (1000+km) between the Torres Strait area and the banana areas south of Mossman, QLD. Under the Banana Replacement Program all susceptible banana plants in the area will be removed and replaced with resistant cultivars so spores blown from the Torres Strait area will not find a suitable host in which to develop.
In Australia, the involved accessions were already present and all the required transactions with the National Quarantine Officials were followed. The fusarium wilt trails were planted as scheduled in November 1995 with accessions recommended by INIBAP's technical guidelines The sites were evaluated every month for a series of external symptoms which will be correlated to internal symptoms following harvesting. At Cudgen, fifteen months after planting, 12 genotypes out of 22 of Race 1 did not present external symptoms, while at Warmuran using Race 4, 10 out of 21 genotypes did not show external symptoms. The results from the trials in Australia and Tonga were presented at a Global IMTP meeting held in March 1997. Together with other NARS/Institutes, IMTP is developing as a truly international cooperative effort not only in the South Pacific but world wide in banana growing areas.