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With the reduction in available chemistry, concerns around resistance and ever-increasing workload pressures, optimising spray timing and effective tank mixtures is more important than ever in enhancing disease control in cereals.

Below you’ll find lots of resources to support you in optimising your disease control programme.

Overview

Many diseases can damage your crop’s yield potential at T1. So it’s critical to get the timing right, and choose the best broad spectrum fungicide to keep your crop protected up to T2.

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Potential yield loss from disease in your crop*:

Up to 50% Septoria

Up to 30% Eyespot

Up to 50% Yellow Rust

Up to 20% Mildew

 

*Source: AHDB

 

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Getting the timing right

A T1 spray applied too early usually results in poorer disease control on the emerging leaf 3, due to a lack of coverage on the leaf as it emerges after application. Whereas, a T1 application applied too late will leave leaf 3 exposed to infection for longer. As a result, any fungicide will need to work harder to control latent Septoria, and can have a negative impact on product efficacy.

This video gives advice on how to get the best out of using a T1 fungicide to control disease in wheat, as well as how to pinpoint the correct timing for T1, and fungicide choice in different scenarios.

 

 

 

  

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Identifying leaf 3

The primary goal when applying a T1 fungicide is to control Septoria on the recently emerged final leaf 3 and leaf 4 at GS 31 – 32.

Richard Cromie, an independent agronomist, says there are 5 key steps to identifying leaf 3 for fungicide timings.  To identify leaves:

  •       Cut one layer at a time
  •       Carefully peel back leaves
  •       Discard outer leaves
  •       Unroll all leaves to reveal the ear inside
  •       Note leaf three must be fully emerged before T1 spraying

Watch Richard talk through his advice on identifying leaf 3 in the following video: 

 

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What fungicides to use at T1?

In most situations with the reduction in efficacy from straight azoles, the best disease control will come from a product containing both succinate dehydrogenase inhibitor (SDHI) and azole active substances.  It is important to keep the rates of azoles in the mix up to at least three-quarter dose to maximise disease control from that component, while also helping protect the SDHI from resistance development.

Bayer’s Aviator (bixafen + prothioconazole) is formulated to provide the correct ratio of SDHI to azole, making it a simple and cost-effective option. It has Leafshield formulation technology, which uses a unique combination of adjuvants to improve crop coverage, leaf penetration and movement of active ingredients within the leaf.

When targeting final leaf 3 emergence, use Aviator 1.0 L/ha + multi-site for 3 – 4 weeks protection.

In some circumstances, where disease pressure, especially from Septoria is high, then the extra curativity offered by Ascra (bixafen + fluopyram + prothioconazole) can be useful at T1.

Alternatively, if disease pressure is very low, typically on late-drilled wheat crops with good inherent varietal disease resistance to Septoria, then a 0.55L/ha Proline (prothioconazole) + multi-site might be sufficient protection at T1.

 

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Overview

Septoria remains the single most prevalent disease in winter wheat and can result in severe yield penalties when not controlled effectively. Whilst robust control requires a programmed approach, protecting the flag leaf is vital to growing your yield potential.

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Optimising your T2 spray

A T2 spray should be applied up to 4 weeks after the T1 spray, when the flag leaf is fully emerged. The primary objective of the T2 spray is to protect the top two leaves of the plant from major disease concerns such as Septoria and rust, during the key yield building growth stage.

The top 3 leaves can represent up to 80% of the plant’s final yield, and so the importance of the T2 spray is clear.

Succinate dehydrogenase inhibitor (SDHI) + azole fungicides are ideally suited to the T2 spray, combining disease control and yield building benefits.

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Overview

At T3 the primary objectives are to control Fusarium and top up foliar disease control. Fusarium can reduce grain quality and final yield by as much as 10%, and is typically worst in years when conditions are humid, showery weather around flowering, which is becoming a more frequent concern in recent seasons.

The advice of most experts now is that mycotoxin control is a necessity for both premium and feed wheat markets, although Fusarium conditions are not conducive to spraying operations which can cause challenges around getting T3 spray timing right.

The following video discusses why it is important to consider both milling and feed wheat at T3.

 

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Optimising T3 timing

The optimum timing for hitting Fusarium is GS 61-63, when the first few anthers have emerged, but not too many are present. Fungicides have a narrow window of opportunity to control Fusarium at T3 – typically three days before or after the optimum

The following videos contain useful information on the correct T3 timing, including an in-field demonstration of varieties not at the correct timing for T3, and discussion on how ear emergence does, or does not, correlate with flowering.   

 

Within a whole crop of wheat there are likely to be a range of different growth stages represented, however the important consideration is the average growth stage of the crop canopy, as Simon Edwards, Professor of Plant Pathology at Harper Adams University explains in the following video.

 

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Fungicide choice at T3

There is a limited choice of T3 fungicides with activity against Fusarium, all of which are azoles. Proline has been shown to have the greatest activity and also provides a broader window of control.

 

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