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Monday 5 December 2016

Choices aplenty for winter crop fungicides

Michael Hennessy

Published 19/04/2011 | 05:00

The choice of fungicides available is huge and this article cannot cover all. Yet, the following will briefly outline possible fungicide choices for winter wheat and winter barley.

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Septoria is the main disease of winter wheat. The main fungicide programme really starts with the T1, which aims to protect leaf 3 and leaf 2, both of which will contribute to final yield. Get the timing of the T1 application wrong and you will struggle to control disease all season.

Apply the T1 when the majority of leaf 3s are emerged. This is not necessarily at GS 31 or GS 32 but can be in between.

The target diseases at the T1 timing in winter wheat are septoria, eyespot (in continuous tillage ground) and, to a lesser extent, mildew. Include Chlorothalonil (Bravo) in all T1 applications. Use a high rate (80pc+) of a triazole or triazole mix at the T1 timing -- Venture Extra, Gleam, Tocata or Proline can be used. Cheaper products containing epoxiconazole could be used where eyespot is not set to be a problem.

The T2 or second main fungicide timing should be targeted at the flag leaf emerged. This will comprise of a high-rate triazole (80pc+) + SDHI + chlorothalonil. This timing generally returns the most money, therefore you should aim to spend the most money here. Target the use of a product containing a SDHI (Aviator, Venture Extra) as these have shown a higher yield in trials when used at this timing.

The final application (T3) will again consist of a triazole mix of products (Caramba, Folicur, Gleam, Prosaro, etc). These will give protection from fusarium (50pc control is regarded as good control). The addition of a strobilurin may be justified in high-yielding situations.

Start planning barley fungicide strategies early so that products can be purchased on time and at a lower cost. Generally, two fungicide applications are needed to keep disease at bay.

Varieties with good disease resistance, such as Quench, Propino or Magaly, can lend themselves to a low fungicide strategy, eg, reduced rates at both timings. Keep a close eye on Snakebite for rhyncho and Azalea and Cocktail for net blotch at an early stage.

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The first fungicide can be applied from mid to late tillering but is generally applied around the first node-detectable stage. Half rates are generally sufficient. Products such as Proline (prothioconazole), Punch C, Lyric, Stereo, etc, will all do an excellent job at this stage.

Where rhyncho is a problem early, use Proline at a higher rate (40-50pc of prothioconazole) as it has the best activity of the products mentioned. Include a mildewcide to help dry the lesions. Likewise, where net blotch is a problem, use higher rates of Proline. The addition of strobilurins (Modem, Galileo, etc) may also be justified.

The second fungicide application (T2) will coincide with the flag leaf emerged to awns visible. Triazoles form the cornerstone of disease control at the T2 timing, with products containing prothioconazole featuring strongly (Siltra, Fandango etc). Other alternatives can be used, such as Venture Extra, Allegro Plus, or triazoles plus strobilurin mixes, such as Amistar Opti, Credo, etc.

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