Key Points
- In the hot dry, low disease 03/04 season, fungicides were barely economic at the two trial sites.
- This season’s trial series again illustrated the need to adopt appropriate rates for less susceptible cultivars, since higher rates only served to reduce margins.
- The maximum yield response to fungicide in both trials (0.4t/ha and 0.3t/ha) were achieved with 3 spray programmes however both lost money ($136/ha and $95/ha).
- All strobilurins have performed similarly (when mixed with Opus) in low-moderate disease situations including the new strobilurin Comet.
- Fungicide strategy for less disease susceptible cultivars should remain similar to the status quo (02/03) of: GS39 (flag leaf) Opus 0.25l/ha fb, GS65 (mid-flowering) low rate strobilurin + Opus 0.25l/ha. If disease is observed earlier then: S33 (full leaf 2) low rate strobilurin + Opus 0.25l/ha, then repeated at GS55 (ear half emerged). Monitor the crop for early disease.
- To minimise the risk of strobilurin resistance occurring, it is advised to limit strobilurin use to no more than two applications per season. FAR trials show that following this advice has given reasonable disease control, while maintaining (or improving) profitability.