Key Points
- Leaf rust (Puccinia hordeii) and low levels of a later infection of scald (Rhynchosporium secalis), were the primary cause of yield loss in these trials on the susceptible cultivar Optic
- Responses to fungicide application, yield increases and reduced disease incidence, were similar in both dryland and irrigated trials. In the irrigated trial there was a maximum yield of 8.6 t/ha, a 2.2 t/ha response to fungicide and a $463 MOCC. In the dryland trial, maximum yield of 8.8 t/ha, a 2.4 t/ha yield response and a $519 MOCC.
- Though based on relatively low rates of fungicide the best fungicide programmes still gave over 99% control of leaf rust when assessed during grain fill (GS83).
- The triazole programmes (Opus and Proline applied alone with no mix partners) gave the lowest disease control and yield response of the fungicide treatments. However, they were still highly cost effective relative to the untreated ($200-350 MOCC). Proline was superior to Opus in terms of disease control, yield and margin with a significant yield response in the dryland trial.
- Unlike autumn sown barley and wheat, Proline gave superior leaf rust control compared to Opus at the rates tested.
- With leaf rust as the main disease, Acanto partnered with Proline was the best combination of those tested, being significantly superior to Proline + Protek, Opus + Twist, Opus + Acanto and Fandango at equivalent rates in the dryland trial.
- Proline sets a new standard of disease control in spring barley, but best results are achieved when it is applied in a mixture. If leaf rust is present it is best mixed with a good leaf rust partner, Acanto being the best of those tested in the trials over the last two seasons. Protek (carbendazim) is an excellent low cost partner for Proline but should not be relied on as the sole partner where leaf rust is present or the variety is susceptible to this disease. Similar responses occur in autumn sown barley.