This is a final research report from Hort Innovation’s historical archives. Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.

What was it all about?

Fusarium wilt causes large economic losses to the banana growers of the subtropics in Australia. It also poses the greatest threat to tropical banana production should the highly virulent tropical race 4 strain of this fungus (which is currently present in Northern Territory) arrive in the main production area in Tully, Queensland.

Paradoxically, tissue culture banana plants which are produced to eliminate the spread of diseases including Fusarium wilt, are actually more susceptible to Fusarium wilt when first planted out than plants not derived from tissue culture. One of the reasons postulated for this increased susceptibility is lack of beneficial microbes.

Silicon applications have previously been implicated in enhanced resistance to plant disease. In this study, two types of silicon formulations (potassium silicate and sodium silicate) were applied to banana plants both in tissue culture and as pot plants in the glasshouse. These plants were then challenged with the Fusarium wilt fungus (subtropical race 4, the strain that occurs in SE Queensland). The potassium silicate treatment was the most effective in reducing initial disease symptoms. Silicon applied in tissue culture did have a lasting effect in reducing Fusarium wilt when plants were later challenged with the fungus. However there was no apparent difference between silicon and non-silicon treatments in the final disease assessments taken at ten weeks after inoculation; this was thought to reflect the high inoculum level and ideal growing conditions for Fusarium which would not necessarily reflect conditions in the field. Experiments should now be undertaken in field conditions to determine the best protocol for silicon application. When the fungus was observed at the microscopic level its growth was retarded when observed in the plants treated with potassium silicate. Further research is required, but these results give a useful indication that silicon treatment, even when applied only in tissue culture, may reduce the affects of Fusarium wilt.