Minimising Risk by Shutting the Door on Early Disease
There has long been an argument for preventing disease establishing in winter wheat and barley, rather than resorting to expensive fire-brigade treatments.
But with the decline in curative activity of triazoles against Septoria tritici, and recent experiences of rusts flaring up, the argument is now even more compelling, Syngenta field technical manager, Iain Hamilton, believes.
“Adopting a more preventative approach against disease, and using multiple fungicide modes of action, are strategies that are increasingly talked about to regain control of Septoria tritici,” says Mr Hamilton. “And they are also prudent in barley.
“That’s not only because of the impossible task of ‘buying back’ green leaf area if Rhynchosporium and net blotch take hold, but also because it makes sense to protect barley fungicide chemistry. Preserving fungicide effectiveness is something where everyone plays a part.”
Looking at practical implications, Mr Hamilton says T0 and T1 have taken on much more important roles. “In winter wheat, T0 should aim to reduce pressure from over-wintered diseases such as Septoria and rusts, and protect against T1 delays.
“Our guidance here is to use CHEROKEE. This is proven and very cost-effective, providing a high loading of two triazoles, but it also has the important multi-site BRAVO element already built in. So you’re protecting the crop with multiple modes of action from an early stage.
“In trial plots, CHEROKEE has given a greater reduction in Septoria than using a triazole/morpholine product and simply increasing its dose.”
Following T0, Mr Hamilton says T1 is a key timing for maintaining preventative control of Septoria, and potentially rusts. Accordingly, he says a more robust T1 may be needed than used historically – using SDHI + triazole and BRAVO in a three-pronged approach.
“For T1, we advocate the long-lasting SDHI/triazole products of SEGURIS or KEYSTONE, mixed with BRAVO, to protect leaf three and provide persistent protection towards T2. A three-pronged programme has given an extra 1 t/ha over triazole + BRAVO in trials.
“Meanwhile in winter barley, T0 aims to prevent diseases such as Rhynchosporium, net blotch and mildew establishing. Using KAYAK + morpholine at T0 targets all these and KAYAK contains cyprodinil, an important active ingredient for resistance management.
“At T1 in barley, we again advocate an IZM-based SDHI, such as CEBARA, for long-lasting protection of important lower leaves.”