Epsilon Archive for Student Projects

Abstract

Fungal plant diseases have typically been controlled by the application of chemical pesticides. However, excessive use of chemical pesticides may produce undesirable side effects including fungicides tolerance in pathogens and environmental problems, if not handled correct. Application of biocontrol agents (BCA) alone or in combination with low dose of fungicides is one of the alternatives to the use of higher dose of chemical pesticides and lower the general use. The aim of this study was to investigate the potential of combining the fungal BCA Clonostachys rosea with a low dose of fungicides to control fusarium foot/root rot on wheat and barley, which is caused by the fungal plant pathogens Fusarium graminearum and Fusarium culmorum.

In order to find a fungicide and a dose that is compatible with C. rosea, an in vitro test was performed to analyse the fungicide tolerance of C. rosea. For this experiment, different concentration of six chemical fungicides, with different mode of actions, were selected. Fungicide tolerance/sensitivity of F. culmorum and F. graminearum to these fungicides was also analysed. The assay showed that C. rosea has different level of tolerance/sensitivity to different fungicides. In addition, our results showed that C. rosea has a relatively better ability to tolerate prothioconazole (commercial name Proline) at 1/30 and 1/60 concentration of recommended full dose compared to F. graminearum and F. culmorum. Based on in vitro result, Proline was selected for seed coating and in planta bioassay experiment against Fusarium foot rot on wheat and barley. A growth chamber sand seedling test showed significant reduction in disease severity in barley seedling when seeds were treated with C. rosea spores compared to control treatments. Similarly, barley seeds treated with full dose of Proline alone or a low dose of Proline in combination with C. rosea completely inhibited the Fusarium foot rot on barley. Our results showed no significant difference in disease severity on barley between Proline treated and C. rosea + Proline treated barley seeds. Analysis of plant health parameters showed that barley plants treated with C. rosea alone or with a combination of C. rosea and Proline had significantly higher shoot length, shoot fresh weight and dry weight compared to barley seedling from seed coated with only Proline. The bioassay experiment on wheat plants failed since no disease development was observed in any treatment, including the Fusarium control. In summary, the result from this study showed that the biocontrol fungus C. rosea can be combined with a low dose of Proline. The treatment with a combination of C. rosea and low dose of Proline showed similar effect to that of full dose of Proline in controlling fusarium foot rot on barley. The result from this study will help to formulate integrated pest management strategy by mixing the fungus C. rosea with Proline and apply it on the specific crop accordingly.