Longevity of protection is key at T2
In the third of BASF’s Funginar series, this one giving an update on disease control in winter wheat, Jon Helliwell, Business Development Manager BASF, spoke of the benefits of using Revystar ® XE at the T2 timing. Dr Helliwell said, “T2 fungicides have a fundamental impact on mitigating risk and allowing the true potential of the crop to be realised, targeting the current infection and for future protection. Regardless of the season independent data shows there is a positive yield benefit of using Revystar® XE right up to full label dose.
From season to season, despite changing weather patterns we can see the same general trend in terms of Septoria progression, with the rate of progression largely a factor of temperature and rainfall. Varietal choice has a major impact on the disease’s progression with more resistant varieties having a longer latent period which gives increased timing flexibility of fungicides. Fungicides themselves have a very significant impact on the rate of Septoria progression. However, where spray timings have been stretched or on weaker varieties you would again expect higher levels of infection particularly on untreated leaf 2.
AHDB Fungicide Performance Curves illustrate data from single application trials, in either protectant or eradicant scenarios. These trials are purposefully designed to pull apart programmes. In 2020 disease pressure was still very low at the T2 timing with Septoria coming into the crop late, so longevity of protection was crucial. Even in that absence of Septoria, the half label dose of Revystar® XE out yielded the full label dose of Ascra® Xpro.
No visual expression of Septoria does not mean no Septoria
Over a period of 3 years across 1400 untreated Septoria assessments from BASF trials, the results highlighted that following a T1 application, growers should not expect to see Septoria on leaf 2 or the flag leaf when the crop hits GS37-39. Septoria has simply not had adequate time to move through its latent period on the newest emerging leaves. However, this does not mean the upper leaves are clean, in particular untreated leaf 2 which has been exposed to infection for a number of weeks. Septoria constantly seeks to out-manoeuvre growers, its development is a continuous process. Any leaf wetness, along with direct leaf to leaf contact and frequent rain splash events will continue transmission up to yield critical leaves.
Longevity of protection remains key at T2
Alongside outstanding curativity, Revystar® XE provides a new benchmark for longevity of protection.
The job of the T2 is both to protect and control any infection on the flag leaf and leaf 2 and also provide longevity of protection in variable weather for typically 6-8 weeks after application, a significant amount of time to expect activity against Septoria. Therefore, at T2 fungicides require both long term activity and high curativity to cure any latent infection and protect the flag leaf, leaf 2 and leaf 3 as we move through the season. Litre for litre Revystar® XE remains the most curative product on the market.
In ADAS trials comparing different fungicide programmes, Revystar® XE showcased its longevity of protection, its ability to protect regardless of when Septoria enters the crop. In the trials, Septoria arrived in the crop late in the season, 34 days after T2 application there was only 6% visual Septoria infection on leaf 1 and leaf 2 in the untreated. Fast forward 11 days to 6 weeks after T2 was applied, and this is starting to ask big questions on the longevity of protection that any fungicide can offer. In the untreated Septoria developed quickly and stood at 50% visual infection.
52 days after T2 and Septoria had really taken hold, with 100% Infection on the untreated. Revystar® XE was still providing 88% control of Septoria at this timing, highlighting the valuable role that it has to play in terms of longevity of protection. In the absence of CTL in this trial, conventional chemistry (in this case 1.2 l/ha Ascra®XPro) provided 53% control at this timing by comparison. Interestingly even the addition of 1 l/ha folpet to 1.2 l/ha Ascra® Xpro did not produce the same level of Septoria control as 1 l/ha Revystar® XE at T2.
Delayed and early T2 applications
The well-timed programme is still the one to target, with GS 39 optimum regardless of what fungicide you use, however, data from trials shows Revystar® XE is very flexible in terms of timing. Revystar® XE kept the flag leaf, leaf 2 and leaf 3 green even after a 19-day delay to the T2 application. A combination of curative activity when it is needed, and longevity of protection gave Revystar® XE more than 0.5 t/ha yield benefit over conventional programmes of Ascra® Xpro and ElatusTM Era.
If applied earlier at GS37, there is still a benefit of Revystar® XE over conventional fungicides, but clearly GS 39 remains the optimum technical timing.”
Use plant protection products safely. Always read the label and product information before use. For further product information including warning phrases and symbols refer to www.agricentre.basf.co.uk. Revystar® XE contains mefentrifluconazole (Revysol®) and fluxapyroxad (Xemium®). Ascra® Xpro contains bixafen and fluopyram and prothioconazole. ElatusTM Era contains benzovindiflupyr and prothioconazole. Revystar®, Revysol® and Xemium® are registered Trademarks of BASF. All other brand names used on this publication are Trademarks of other manufacturers in which proprietary rights may exist. © BASF 2021. All rights reserved.