In case you are interested in background information for SBI Fungicides, please follow this link: Information on SBI Fungicides
 

FRAC Recommendations for SBI Fungicides

Utilization of fungicide resistance management strategies in practice is one of the most important tools to slow down the evolution of fungicide resistant plant pathogens. FRAC is supporting farmers by publishing annual reviewed Recommendations for resistance management.
 

General Use Recommendations (all Crops)

(No changes in December 2018)

The SBI fungicides represent one of the most potent classes of fungicides available to the grower for the control of many economically important pathogens. It is in the best interest of all those involved in recommending and using these fungicides that they are utilised in such a way that their effectiveness is maintained

The working group concentrates its resources on the major crop/pathogen targets from the point of view of resistance risk. Inevitably many, still important pathogens are omitted. To help in making recommendations for crops and pathogens not directly covered, the following general recommendations can be made:

  • Repeated application of SBI fungicides alone should not be used on the same crop in one season against a high-risk pathogen in areas of high disease pressure for that particular pathogen.
  • For crop/pathogen situations where repeated spray applications (e.g. orchard crops/powdery mildew) are made during the season, alternation (block sprays or in sequence) or mixtures with an effective non cross-resistant fungicide are recommended (see FRAC Code List).
  • Where alternation or the use of mixtures is not feasible because of a lack of effective or compatible non cross-resistant partner fungicides, then input of SBI's should be reserved for critical parts of the season or crop growth stage.
  • If the performance of SBIs  should decline and sensitivity testing has confirmed the presence of less sensitive isolates, SBIs should only be used in mixture or alternation with effective non cross-resistant partner fungicides.
  • The introduction of new classes of chemistry offers opportunities for more effective resistance management. The use of different modes of action should be maximized for the most effective resistance management strategies.
  • Users must adhere to the manufacturers’ recommendations. In many cases, reports of “resistance" have, on investigation, been attributed to cutting recommended use rates, or to poorly timed applications.
  • Fungicide input is only one aspect of crop management. Fungicide use does not replace the need for resistant crop varieties, good agronomic practice, plant hygiene/sanitation, etc.
  • Exclusive frequency measurements of single cyp51 mutations are not sufficient to describe the sensitivity situation towards DMIs but can help to better understand the background of sensitivity shifts.

 
Specific Recommendations by Crop / Pathogen for DMIs, Amines and KRIs

 

Cereals - DMIs and Amines

(No changes in December 2018)

  • The recommendations for the use of DMI and amine fungicides in mixture or alternation programmes with different mode of action fungicides remain unchanged. It needs to be emphasized that it is essential for resistance management purposes to follow strictly the manufacturer’s and FRAC recommendations.
  • Repeated application of DMI or amine fungicides alone should not be used on the same crop in one season against risky pathogens (e.g. cereal powdery mildews, barley net blotch, scald) in areas of high disease pressure for that particular pathogen.
  • Reduced rates of DMIs can contribute to accelerate the shift to less sensitive populations. It is critical to use effective rates of DMIs in order to ensure robust disease control and effective resistance management. DMIs must provide effective disease control and be used at manufacturers recommended rates.
  • When used in mixture recommended effective rates of the SBI must be maintained.
    Split and reduced rate programmes, using multiple repeated applications at dose rates below manufacturer’s recommendations, provide continuous selection pressure and accelerate the development of resistant populations, and therefore must not be used.
  • To ensure good performance and particularly resistance management in situations of even low disease pressure it is essential to adhere to dosages and spray timings as recommended by manufacturers. Curative applications should be avoided. Application timing has to be appropriate to all mix partners’ characteristics. Mixing with a non-cross resistant fungicide at effective dose rates contributes to a more effective disease control and resistance management.
  • The amine fungicides are effective non-cross-resistant partner fungicides for DMIs on cereals for the control of pathogens included in the label recommendation of each respective product.
  • Ramularia leaf spot (Ramularia collo-cygni) in barley: Given that there already exist populations of Ramularia collo-cygni in Europe resistant to all main specific modes of actions it is recommended to add precautionary a multi-site to ensure robust disease control and an effective resistance management in barley

Soybeans: Asian Soybean rust / Phakopsora pachyrhizi – DMIs

(Updated December 2018, minor changes in bold)

Refer to the general recommendations for SBIs.

In addition to ensure robust disease control and resistance management it is essential to

  • Apply DMI fungicides always in mixtures with effective non-cross resistant fungicides (mix partner shall provide control over the spraying interval).
  • Refer to manufacturers recommendations for rates. Reduced rates must be avoided.
  • Apply preventively or as early as possible in the disease cycle.
  • Ensure a proper coverage of the treated crop by appropriate and well calibrated application technology (e.g. to ensure penetration into canopy).
  • Apply DMI fungicide containing products always at intervals recommended by the manufacturers and adjusted to the disease epidemics. Avoid extended spray intervals.
  • Good agricultural practices must be considered to reduce source of inoculum, disease pressure and resistance risk, e.g. no multiple cropping, implement and respect soybean-free periods, consider partially resistant soybean varieties, reduce the planting window, give preference to early-cycle varieties and endorse the destruction of volunteers.

Grapevines: Powdery Mildew / Eryisphe necator - DMIs and Amines

(updated December 2018, no changes in 2018)

  • DMI´s and amines should be used preventative and curative situations should be avoided.
  • The existing strategy for effective disease control and resistance management continues to be successful and the use recommendation is a maximum of 4 applications per season per mode of action. The strategy includes the use of mixtures or alternation with non-cross resistant fungicides.
  • To ensure that SBI's can remain the effective basis for control of Erysiphe necator in grape vine, their use should adhere to the full recommended rate (either alone or in mixture) at the recommended timing and application volume and an accurate treatment of each row.

Apples: Scab / Venturia inaequalis – DMIs

(updated December 2018, no changes in 2018)

  • DMI fungicides are not recommended for season long use and a maximum of 4 DMI sprays either alone or in mixture is recommended.

  • DMIs should be used in mixtures or (block) alternations with a non-cross resistant fungicide. Application of recommended label rates is important.
  • Preventative applications should always be the first choice with DMIs. Curative applications are only recommended when accurate disease warning systems are available.

Grapevines, Strawberries and Raspberries: Botrytis spp. - KRIs

(updated December 2018, no changes in 2018)

 Use KRIs only protectively.
  • Use KRIs only in strict alternation, no block application
  • Solo product as part of alternation programmes:
    • Spray programmes with a maximum of 3 treatments per season: max. 1 application with KRIs
    • Spray programmes with 4-5 treatments/season: max. 2 applications with KRIs
    • Spray programmes with 6 and more treatments: at the maximum one third of all Botryticide-applications
  • Use in mixtures:
    • Both partners - if applied alone at the dose used in the mixture - must have sufficient activity against Botrytis.
    • Not more than 50% of all Botryticide-treatments should be made with KRIs-containing mixtures.
For sound resistance management, good agricultural practices, including phytosanitary measures and crop protection, should be followed carefully.
 

Monitoring Results and Use Recommendations

At the annual meeting, the working group reviews the current year's monitoring results and decides whether they require changes be made to the next year's use recommendations.  The minutes of those meetings are below.


Contact

Dr. Andreas Goertz
Chair

Bayer AG, Crop Science Division
Alfred-Nobel-Strasse 50,
Building 6240
D-40789 Monheim

andreas.goertz@bayer.com