These recommendations are crop (and disease) specific recommendations which should be used in ADDITION to the general use recommendations to manage resistance development. They are excerpted from the minutes of annual meeting of the WG.

Cereals - DMIs and Amines

(Updated February 2018, changes in bold)

  • 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 February 2018, 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. Refer to manufacturers recommendations for rates.
  • Apply preventively or as early as possible in the disease cycle.
  • 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.

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Dr. Klaus Stenzel
Chair

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

klaus.stenzel@bayer.com