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20 May 2021 - by Andrew Bailey - Cereals Fungicide Technical Specialist
2 min

2021 - T2: the key protection window for wheat

With the T2 spray timing for wheat crops rapidly approaching – and the current spell of unsettled and warmer weather (which will exacerbate the potential for septoria to develop and spread) forecast to continue for the next week at least – our thoughts turn to providing appropriate protection to keep the top two leaves clean and disease free.

T2 fungicide treatments are the most important in terms of protecting final yields as it is this spray timing which provides protection to Leaf 1 and Leaf 2; themselves contributing up to 70% of the crop’s final yield potential.

T2 applications should therefore be applied when the flag leaf is fully emerged on the main tillers and should be robust enough to provide adequate levels of protection against septoria and rusts – in particular brown rust which can be prevalent from this stage onwards.

Don’t forget the folpet

To provide the very best levels of protection against septoria, and to safeguard the yield potential of crops which may already have some disease on lower leaves, T2 sprays should include three modes of action: an azole, an SDHI or Qil fungicide (e.g. fenpicoxamid) and a multi-site (folpet).

211016_P24_Septoria_Early_MainSeptoria 

Whilst the azole and SDHI components will provide strong protection against septoria and other fungal diseases, the efficacy of these single site actives is under pressure as a result of sensitivity shifts in the septoria population. As a new active ingredient, fenpicoxamid isn’t currently under the same resistance pressures as the more established azole and SDHI chemistries. However, as this is also a single site active, it too will become subject to the development of less sensitive strains from first use. A combination of active ingredients should therefore be used to slow the erosion in efficacy of these ‘at risk’ chemistries.

Research has shown that the inclusion of a multi-site fungicide such as ARIZONA (500 g/l folpet) can reduce the rate at which the resistance to single site modes of action develops, thereby extending their effective lifespan.

FRAG-UK (Fungicide Resistance Action Group UK) therefore recommends that SDHIs should be applied in a balanced mixture with at least one fungicide with comparable efficacy from a different mode of action (e.g. an azole) and a multi-site such as folpet.

Optimal uptake

The ability of azoles, SDHIs and Qil fungicides to move into the leaf is important at T2 in order to achieve curative control of potential latent septoria infection on the upper leaves. It is therefore vital to ensure that any tank mix partners don’t compromise the uptake of these fungicides: ARIZONA (500 g/l folpet) is the ideal T2 tank mix partner as it does not antagonise the uptake of azoles, SDHIs or Qil fungicides and can therefore be included without affecting their curative activity.

Key messages for T2

  • T2 is the critical timing to protect yield
  • Use a balanced mixture of effective partners incorporating products with different modes of action
  • Including ARIZONA at T2 improves septoria control and reduces the resistance risk for other single site active ingredients
  • ARIZONA should be included at 1.0-1.5 l/ha depending on the prevailing risk factors (varietal disease resistance, drilling date, geographical location and time gap since the T1 treatment was applied). In most scenarios 1.0 l/ha of ARIZONA in mixture with partner products will suffice, but in higher risk cases the rate should be increased to 1.5 l/ha
  • Include ARIZONA to add efficacy and reduce resistance development
  • ARIZONA does not antagonise the uptake of partner products
    Folpet Fungicide Diagram-1

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Andrew Bailey - Cereals Fungicide Technical Specialist
Andrew Bailey - Cereals Fungicide Technical Specialist
One of the UK arable sector’s most experienced fungicide specialists. With a background in applied biology (specialising in crop science and plant pathology), and with a career spanning 30 years in field based research, fungicide development and fungicide technical support, Andy has worked in the crop protection sector on a UK, European and global level.

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