Appropriate Doses Network: up-to-date information on fungicide performance for wheat growers
About this project
Advances in fungicide chemistry play a key role in maximising economic returns from wheat production. With grain values stronger than for some time, but high crop establishment and nitrogen costs, it is crucial that the investment made in establishing and growing green crop canopy is protected through effective disease management. The development of fungicide resistance threatens disease control, making it more important that the industry uses new fungicide active substances and modes of action efficiently. The project reported here assessed the performance of a range of established and newly introduced fungicides against the major economic diseases of UK wheat. Dose-response curves were quantified to help establish the doses required to obtain effective control, even under high disease pressure.
Each of the fungicides tested was applied as a single spray to the upper leaves, at quarter, half, full and double the label recommended dose, and untreated plots were included for comparison. Double dose treatments were applied for experimental purposes and must not be applied to farm crops. The conclusions from this work were widely reported during the life of the project, at HGCA events, Cereals 2005, 2006 and 2007, and in the farming press, so the practical messages may no longer seem 'new'. This report sets out the dose-response curves for all the diseases and products tested. In summary, the main conclusions were:
Septoria tritici: The decline in the performance of triazole fungicides seen over recent decades appears to have stabilised. Epoxiconazole and prothioconazole both continue to provide good control, provided the dose used is sufficiently robust for the disease susceptibility of the variety and disease pressure. The addition of chlorothalonil or boscalid is recommended. The addition of strobilurins to good triazoles adds little to septoria control, but is justified for rust control (see below).
Stagonospora (Septoria) nodorum (glume blotch): This disease remains a substantial risk in the south west. Products based on prothioconazole or epoxiconazole gave good glume blotch control, as did pyraclostrobin.
Brown rust: 2007 was a particular severe brown rust season across much of southern and eastern England, due to high spring temperatures and a breakdown of disease resistance in some major wheat varieties. Strobilurins and triazoles have maintained their effectiveness against brown rust. The most effective control was given by Fandango, Tracker and Vivid. Yield responses in the trials (as in farm crops) were related to control of rust and septoria, and the largest yield responses were given by Opus + Comet, Prosaro, Tracker and Fandango.
Yellow rust: Fungicides or fungicide mixtures containing epoxiconazole, prothioconazole or tebuconazole all gave excellent control, usually even at low doses. The strobilurins azoxystrobin and pyraclostrobin were also effective. Control by prothioconazole appeared to be improved by the addition of fluoxastrobin (as Fandango).
Powdery mildew: A range of new active substances have provided a substantial improvement in mildew control. Metrafenone (Flexity), proquinazid, (Talius) and the more recently introduced cyflufenamid (Cyflamid), gave excellent control even at low doses. Yield responses were modest (as mildew is less damaging to yield than septoria or rusts), but economic.
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