New Cherokee tank mixes have been introduced by Syngenta for use where septoria risk is high, and eyespot is present.

Previous guidelines for the product have provided growers with the technically equivalent rates of Cherokee (propiconazole + cyproconazole + chlorothalonil) to epoxiconazole plus chlorothalonil, the firm’s Iain Hamilton says. “They deliver the same performance, but cost less to do it.”

But where septoria pressure requires an epoxiconazole dose of over 0.75 litres/ha, the equivalent dose of Cherokee would be over the 2.0 litres/ha maximum dose, he says.

To overcome those limitations, Syngenta has developed recommendations to tank-mix Cherokee with either prothioconazole or Tracker (boscalid + epoxiconazole).

Where eyespot risk is low to medium, and septoria pressure high, the recommendation is to mix 1.25 litres/ha of Cherokee with 0.4 litres/ha of Proline, while in higher eyespot situations add 0.75 litres/ha of Tracker, Mr Hamilton advises.

In seven Irish trials in 2006/07 the prothioconazole mix yielded around 0.3t/ha more than a higher 0.6 litres/ha dose of prothioconazole + Bravo mix. Similarly in a Velcourt trial last season, the mix gave the best disease control and an extra 0.4t/ha over the higher prothioconazole dose, albeit using a higher 1.33 litres/ha dose of Cherokee, he says.

1.25 litres/ha of Cherokee + 0.4 litres/ha Proline and Proline (0.6 litres/ha) + Bravo (1.0 litres/ha) treatments cost around the same at around £26/ha, Richard Palmer (pictured), an independent agronomist from Farm Vision, says. He used the combination commercially on a wide area at T1 in wheat last season.

“The mix covers all the bases. It is a strong septoria package and when you’re using Proline its big weakness is brown rust, which you get from cyproconazole.

“It formed my core T1 treatment last year. I used it on around 4000ha of wheat.”

Performance was good, he says. “It helped give fantastic yields for the investment, and while I haven’t got any specific trials results, the Syngenta results back up what I felt.”

In high eyespot situations Syngenta recommends using 0.75 litres/ha of Tracker in combination with Cherokee. Again in trials it has performed better than the 1.0 litres/ha Tracker plus Bravo mix growers might use in that situation, Mr Hamilton says.

For example, in an ADAS trial the 1.33 litres/ha Cherokee mix gave an extra 0.7t/ha, worth an extra £56/ha based on a wheat price of £110/t, over the higher dose Tracker treatment, while across five sites the average was £13/ha, he says.

“All these options are geared towards improving returns on fungicide investment,” he concludes.