At T1 in 2021, Septoria remains the main target

Key Points

  • T1 focus on Septoria, yellow rust and eyespot this year.
  • Many T0s have not been applied due to either a lack of yellow rust or inability to travel – this has implications for the strength of T1 required.
  • There are season-lasting repercussions of using a weaker T1 on disease control – the previous ‘backbone’ to many conventional programmes of CTL should not be underestimated.
  • Aim the T1 timing for when the majority of main tillers have final leaf 3 at least ¾ emerged. Very late sown or backward crops have fewer leaves – it can often be final leaf 3 and not leaf 4 emerging at GS31.
  • UK Cereal Pathogen Virulence Survey meeting highlights further changes to yellow rust populations – targeting early disease control remains key.

T1 Recommendations

Strongest all-round disease control, fundamental to maintaining crop potential
0.75 l/ha Revystar® XE

  • Proven control of Septoria from both Xemium® and Revysol®
  • Strong control of yellow rust
  • A strong level of eyespot support from Xemium®
  • Effective mildew management, keeping infection within the base of the crop.

High level of Septoria pressure
0.75 l/ha Revystar® XE (+ folpet)

  • The addition of folpet improves Septoria efficacy in the highest pressure scenarios, even with the strongest chemistry in Revystar® XE
  • The benefit of folpet reduces as the strength of the mix partner increases
  • Across BASF trials, yield response to folpet inclusion with Revystar® XE is varied.

High yellow rust pressure
0.75 l/ha Revystar® XE + 0.4 l/ha Comet® 200

  • Both Xemium® and Revysol® have activity on yellow rust - The combination within Revystar® XE gives a strong level of yellow rust control
  • F500® provides effective yellow rust control at stages of the lifecycle at the leaf surface (i.e. during initial spore germination and infection, and end of lifecycle sporulation). Rust active azoles have strongest activity once infection is inside the leaf (i.e. mycelial growth). Utilising both F500® and a rust active azole gives complementary support to any fungicide program.

Disease considerations at T1

Current levels of Septoria are high within BASF’s national trial network. Yellow rust was evident in at risk varieties and should be monitored - active infection has declined in recent weeks.

At T1 in 2021, Septoria remains the main target

Visual disease levels are very variable in the run-up to T1 applications, ranging from little visual infection in late drilled stronger varieties, to very high levels of Septoria in certain geographies. Cold nights will have extended the latent period of Septoria, whilst reducing some of the previously reported yellow rust infection. It is likely that fewer than planned crops will have therefore warranted a T0 application, and those that received one will have not been targeting septoria. However continued leaf wetness (including overnight dews) will aid transmission up to yield bearing leaves, and should not be underestimated.

Any sub-standard level of control will allow infection to establish, increasing pressure on the T2 application particularly for the untreated leaf 2 which will have been exposed for a significant period of time prior to the T2 timing. Disease control strategies should therefore be based around a Septoria focus at T1 and T2, with regular crop inspections undertaken to highlight any new yellow rust risk.

Getting T1 disease control right with Revystar® XE is fundamental to maintaining crop potential.

Revysol® performance remains superior, even in cooler conditions

Whilst cooler conditions give some relief to yellow rust infection, they bring an additional challenge – the uptake and subsequent performance of conventional azoles on Septoria. Over a large meta-analysis of trials data, Revysol® continues to perform even in cooler conditions, as often experienced at T1. This gives greater reassurance that Septoria control strategies are optimised at this crucial timing.

Continued vigilance for yellow rust (particularly if no T0 was applied) is also required

The latest March UKCPVS meeting highlighted that across the 306 samples received in 2020 (88 different varieties), new pathotypes did emerge in 2020 but at low frequencies and with no clear geographic pattern ( Click here to know more ). Many RL varieties showed very good adult plant resistance”, but a new yellow rust watch list is now available capturing the varieties most likely to perform out of line with the disease ratings published in the AHDB RL.This helps to focus early-season management, particularly on varieties such as Skyfall, KWS Kinetic and KWS Kerrin. Localised changes to yellow rust populations have highlighted the need for early eradication and well-timed T1 and T2 sprays. Ensuring that the gap of fungicide protection (particularly on untreated leaf 2) isn’t unduly stretched is vital in this faster cycling disease. An additional rust-specific spray targeting leaf 2 at GS37 may be required in the highest risk scenarios if T1 applications are applied early.

Eyespot remains a key target at T1

  • Only 3 varieties on the 2021-22 Recommended List have a rating greater than 5 (KWS Zyatt, Sykfall and RGT Ilustrious).
  • Dose of active ingredient applied is a key consideration for effective eyespot suppression.
  • Xemium® (within Revystar® XE) provides a strong level of eyespot suppression across both strains, whilst also providing additional AgCelence® benefits to straw strength, increase water use efficiency and extending the duration of green leaf area.
  • Boscalid (within 0.4 l/ha Entargo®, and previously in Tracker®) remains a key active on eyespot, and can be considered at T1 in combination with Revystar® XE where eyespot risk is expected to be severe.

Timing

Later drilled cereals or those held back by recent weather will move through growth stages more quickly than usual. More backward crops will have produced far fewer leaves over winter and may visually look sparse. However crop development is largely driven by day length (modified to some extent by temperature), and so stem extension and final leaf three emergence can occur in deceptively small plants.

Careful dissection is required to determine which leaf layer has emerged in mid-April – reliance on nodes can be deceptive. Final leaf three can emerge at GS31 (rather than the normal GS32). This can have important consequences for fungicide timing to ensure adequate protection of yield influencing leaf 3, and PGR applications where label growth stage restrictions may affect applications.

If the T1 spray is applied too early, part of leaf 3 and all of leaf 2 will be exposed to disease later in the season. This has implications for the strength of fungicide required, particularly if the T2 application is subsequently delayed by weather.

Nitrogen use efficiency

Following the wet winter, soil mineral N levels are low and optimising capture of applied N is vital. Xemium® has been proven to improve use of applied nitrogen, enhancing green leaf retention. Appropriate manipulation of the canopy is crucial, as overly thick or overly thin crops are at increased risk of disease ingress.

Disclaimer

AgCelence®, F500®, Comet® 200, Entargo®, Tracker®, Revystar® XE, Revysol® and Xemium® are registered trademarks of BASF. Revystar® XE contains Revysol® and Xemium®. Revysol® contains mefentrifluconazole. Xemium® contains fluxapyroxad. Comet® 200 contains pyraclostrobin. Entargo® contains boscalid. Tracker® contains boscalid and epoxiconazole. Always read the label and product information before use. For further product information including warning phrases and symbols, you can refer to agricentre.basf.co.uk © BASF 2021 | All rights reserved. All other brand names used on this publication are Trademarks of other manufacturers in which proprietary rights may exist.

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