If you can see ramularia on the crop it’s too late to do anything about it. The disease has quickly become a real problem in barley production in Ireland.
The banning of chlorothalonil took away a key tool in its control.
Deirdre Doyle, agronomy technologist, went through the latest research on the disease at last week’s Teagasc national tillage conference.
The key message was that ramularia is highly unpredictable and there is no varietal resistance available at present so managing crops to avoid stress is crucial. This can be difficult in Irish weather, but providing crops with optimum nutrition and avoiding tank mixes that could add stress to the crop due to the number of products or having a hot mix should be avoided.
After that, it is important to protect tillers on the crop and the upper canopy. That means keeping on top of disease control. Folpet, a multisite fungicide, has fallen in as a replacement to chlorothalonil in fungicide programmes.
At the conference, Deirdre questioned if it was a replacement for chlorothalonil in winter barley.
Looking at the data, two applications of Folpet were needed to reach the heights of chlorothalonil’s control.
Proline and Modem at GS31-32, along with Siltra and chlorothalonil at GS45-49, yielded 10.2t/ha. Another crop receiving Proline and Modem at GS31-32, Folpet at GS37 and Siltra plus Folpet at GS45-49 yielded 10.3t/ha. So, crops can hit the yields, but with more applications and higher rates.
A crop that received Proline and Modem at GS31-32 and Siltra and Folpet at GS45-49 yielded 9.8t/ha. Therefore, the decision has to be made if the spend is worth it.
On spring barley, one application of Folpet at the main fungicide timing of GS45-49 (along with an SDHI fungicide) instead of 1L/ha of chlorothalonil, saw similar yields on both Laureate and Planet over a three-year trial.