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Protecting each new leaf: wheat treatments at T1.5

For most UK growers, the first half of spring 2023 has been a frustratingly wet affair, with the damp conditions complementing the winter’s mild conditions resulting in an abundance of septoria in the lower canopy of a many wheat crops.

With further significant rainfall events forecast throughout May, the potential for existing septoria infections to spread to newly emerging leaves will remain high. Where crops are at risk from a range of factors (see below), growers might want to apply an intermediary fungicide treatment at the T1.5 timing (GS33-37) to ensure all new growth remains adequately protected.

Risk factors

A T1.5 treatment should be considered for crops which meet any or all the following criteria:

  • The crop was drilled early and has developed a high septoria loading.
  • The variety is classified as susceptible or moderately susceptible to septoria.
  • The interval between the T1 and T2 treatments is likely to be extended.

Protecting each new leaf

The most effective way of controlling septoria is to prevent infection from occurring in the first place: this means ensuring each newly emerged leaf is protected before the first disease spores land on it and germinate.

Although Leaf 3 and Leaf 1 should be protected by the T1 and T2 treatments respectively, an extended period between treatments could leave Leaf 2 exposed to infection. A T1.5 treatment can counter this threat and can often be applied in conjunction with a PGR spray.

Folpet at T1.5

Where septoria is the main threat, the first choice of active ingredient should be a multi-site fungicide, with Arizona (500 g/L folpet) providing good contact protection for the period until the flag leaf spray (T2) is applied: folpet not only helps the crop to stay ahead of septoria by providing valuable efficacy against infections, but also delivers a yield benefit by helping the crop to maintain its green leaf area for longer.

Find out more

For more information about how ARIZONA could protect your wheat crop, contact your Regional Agronomy Manager by calling the ADAMA technical helpline on 01635 876 622 or via email at

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ARIZONA® (500 g/L folpet) is a unique multi-site fungicide which provides protectant activity against septoria, rusts, rhynchosporium, ramularia and net blotch in wheat and barley. It also fulfils a useful anti-resistance role by protecting the efficacy and longevity of single site partner products.