Cereal growers should use the minimum number of azole fungicides in a season to control disease and keep those applications at a high rate to prevent resistance to fungicides building up.
This approach will slow the development of resistance to these azoles and also help protect the new SDHI generation of fungicides from seeing resistance occur in the field.
The advice comes from the UK Fungicide Resistance Action Group, which gives guidelines to maintain azole and SDHI fungicide performance in the years ahead, especially against wheat’s number one yield-robbing disease septoria.
It suggests focusing azole use at core T1 and T2 timings, as their use at T0 and T3 will increase selection for fungicide insensitive septoria disease strains in wheat.
“The aim is to reduce the number of azole treatments a crop, and use mixtures of modes of actions effective against septoria,” the group advises for spring 2014 from its research work supported by the HGCA.
It suggests using alternative to azoles at T0 such as multi-site protection products – which are at a low resistance risk – for septoria, and use strobilurins against rusts at this early season spray.
The group also advises against the use of additional or split sprays such as at T1.5 or T4 timings.
“Use robust doses of azoles at core timings. This will help to achieve effective control, maximise protection of the SDHI components in mixtures and minimise the need for additional/split sprays,” it adds.
Two the major azoles in use are prothioconazole, such as Proline, and epoxiconazole, such as Ignite and other brands, and both are used in popular SDHI-azole products such as Aviator, Adexar and Seguris.
Growers are also advised to use minimum SDHI doses and number of treatments to achieve effective control and reduce the risk of resistance to SDHIs being seen.
“Partnering with a robust dose of azole will reduce SDHI resistance risk without markedly increasing selection for azole resistance,” the group says.