Appropriate fungicide doses on winter barley: producing dose-response data for a decision guide

Abstract

The aim of the research was to provide an independent source of information about the activity of current and newly introduced fungicides against the major barley diseases. The diseases investigated were rhynchosporium, brown rust, powdery mildew, net blotch and ramularia. Protectant and eradicant properties were measured in field trials carried out throughout the UK and Eire under high disease pressure conditions.  The efficacy of fungicides does not remain static, and the results on disease control from this research can be used alongside other evidence to highlight situations where the efficacy of disease control may be changing in the field.  It is important to ensure growers receive the most up-to-date information about the activity of fungicides, so the research aimed to deliver the results to growers annually at HGCA Disease Roadshows.

The project has shown that the recent introduction of the fungicides Proline and Fandango provide a major step forward in the control of rhynchosporium whilst also delivering good control of powdery mildew, net blotch, brown rust and ramularia.  Effective disease control was achieved with these fungicides alongside a yield benefit, which makes these new fungicides cost-effective to use. The research also highlighted fungicides, which either show disease activity limited to one disease, or which are primarily eradicative or protective in activity.  These specific fungicides are an essential component of the spectrum of fungicides available to a grower, since they have different modes of action to the main broad-spectrum strobilurin and triazole fungicides. More specific fungicides can however be more difficult to use, which is why the tables developed through this research on disease eradicant and protectant activity, yield and green leaf area retention, can assist growers to use them in combination with the more broad-spectrum fungicides.

Getting the results out to the HGCA levy-payers quickly meant the procedures in assessing trials, collecting data, analysis and dissemination were all focussed on this aim.  The data collected over three years will be a useful foundation for future research. It will provide a reliable platform to determine how new fungicides approved for use in 2005, change in their activity when used more widely as opposed to their limited use in field trials up to now.

Results were reported in a SEERAD funded Technical Note entitled "Barley Disease Control". This note placed the appropriate dose data in a practical context of managing barley diseases. More effective ways of getting the information across to growers are being developed as part of an Appropriate Dose Curve Generator.  This web-based tool will allow growers to compare dose curves generated from this three year study of different fungicides.