Dealing with Fungicide Resistance

  • Septoria remains the key disease of focus
  • There has been a further shift in sensitivity to septoria recorded for SDHIs, but they remain a key part of disease management strategies
  • The efficacy of conventional triazoles (including prothioconazole) has continued to decline
  • Revysol® sensitivity remains stable, with high in-field efficacy
  • Protection of SDHIs remains vital – Partnering appropriate doses of an SDHI with the strongest triazole in Revysol® remains a key approach
  • Combine the best tools available – strong varietal genetics partnered with strong fungicide programmes to minimise further resistance shifts

BASF Winter Wheat recommendations for 2021

Fungicide applications should consist of the strongest chemistry, giving all-round disease protection:

* 0.75 l/ha Revystar® XE at GS 32

* 1 l/ha Revystar® XE at GS 39

High Septoria levels despite the cold weather

Septoria levels are high in crops, although the frosts gave a welcome relief from the mildew and yellow rust infections that were starting to appear. Septoria remains the one disease that continues to escape our control programmes every year, and effective control strategies need to be considered using appropriate rates both from a resistance management and efficacy perspective.

Winter wheat in central UK exhibiting high levels of Septoria

SDHI Resistance monitoring

SDHIs remain crucial for disease control. Data collected in 2020 by BASF from around the UK and Ireland has indicated that ca. 80% of the septoria population now has some degree of mutation to this chemical class. Whilst there has been a clear erosion in efficacy as the population has shifted to one that’s more resistant, there have been no reported field failures.

The in-field performance of Xemium® within Revystar® XE remains strong.

Source: AHDB Fungicide performance, Septoria 2020.

"Use the minimum effective dose of SDHI to control the disease" is the message from resistance experts to protect this chemistry class. It is only evident post-season what the retrospective optimum dose for each cropping scenario was, but there are some fundamental considerations that can be made to reduce the further impact of resistance:

  • All commercial SDHIs are cross resistant, with mutations at the fungicide target site reducing sensitivity of the Septoria isolate to the SDHI molecule. Therefore any reduction in sensitivity will impact all SDHIs, although the degree to which this occurs varies based on the intrinsic activity of the individual SDHI in question. Xemium® remains the strongest on Septoria.
  • By applying a higher loading of SDHI to a crop than necessary, you are increasing selection pressure and increasing the risk of resistance development.

DMI resistance monitoring

There has been a further shift in the sensitivity of conventional triazoles (including prothioconazole) in 2020. Latest monitoring shows a stable situation for Revysol®. It is demonstrating much higher levels of field performance than any other triazole on the market. This adds to both disease control and yield, but also maximises protection of the SDHI element of the program. Using an SDHI partnered with the strongest triazole, applied at an appropriate dose and timing continues to be the optimum to minimise any further resistance shifts.

Field performance of azole fungicides over time - Source: Aarhus University – Treatment applied at 2X half dose. Rubric contains epoxiconazole; Proline – prothioconazole; Juventus – metconazole; Folicur – tebuconazole.

Further commentary on resistance and learnings from 2020 can be obtained from a recent dedicated article here.

Revystar® XE continues to outperform

Moving into its second season of commercial use, Revystar® XE continues to show standout performance in terms of both disease control and yield within independent data, both in low disease pressure (2020) and mixed disease pressure (2018-2020) scenarios.

Source: AHDB Fungicide performance, 2020.

Fungicide performance update, covering other key diseases, can be found here .

Disclaimer Revystar® XE and Revysol® are registered trademarks of BASF. Revystar® XE contains Revysol® and Xemium®. Revysol® contains mefentrifluconazole. Xemium® contains fluxapyroxad. 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 2020 | All rights reserved.

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