Key Points
- Fungicides were cost effective in both dryland and irrigated trials of Regency in the 2005 season, despite generally low levels of disease.
- Fungicide increased yield by 0.81t/ha (10.6%) for the irrigated crop with a mean margin over chemical cost (MOCC) of $86/ha (range $-2 to $168/ha). Dryland yields were improved by 0.64t/ha (14%) with a MOCC of $62/ha (range $20 to $100/ha).
- Two sprays at flag leaf emergence (GS39) and mid-flowering (GS65) were generally superior in the irrigated situation, whereas there was little difference between the single and two spray programmes in the dryland trial.
- The addition of low doses of strobilurin (Comet 0.2l/ha) to Opus 0.25l/ha had its greatest impact at mid flowering in the irrigated trial, producing the highest MOCC of $168/ha. Increasing the Comet dose to 0.4l/ha or incorporating Comet at both flag leaf emergence and mid-flower, reduced margins.
- On the dryland site, the addition of strobilurin gave cost effective yield increases over straight Opus, but there was no advantage to making strobilurin addition at the later timing, a fact likely to be related to the curtailed grain-fill on the dryland site. The best MOCC ($100) came from two applications of Opus 0.25l/ha with the addition of Comet (0.4l/ha) at GS39.