Tuesday, July 13, 2010

TIMING FOR BLAST FUNGICIDES

To minimize neck blast with current fungicides, the products MUST be applied preventatively – before the panicles have emerged fully from the boot. The photos below illustrate growth stages for application of the fungicides registered for neck blast prevention, based on the most severe disease pressure situation =[ highly susceptible variety (example = CL 151, Francis, CL 261) + erratic flood depth or shallow flood depth + field with a history of blast disease, etc.].

The photo first photo below is equivalent to late (fully swollen) boot to boot split (5% heading) and is appropriate for the first application. The second photo is equivalent to 50-90% heading and is appropriate for the secondapplication. Note that the bases of all panicles are still in the boot. We believe that when the base comes out, the neck of the panicle often gets infected at that point, and once the fungus is inside, fungicides cannot do much to prevent subsequent damage.


For one-shot applications to a field, the best timing is between these two growth stages, when about 1/3 of the panicle is emerging from the boot (30-50% heading), as seen in the first photo, far right tiller. It is always better to err on the early side of these stages, than later. In most cases, a late boot to boot split application can be followed by the second application in 5 days and things should work out.

While 19 oz of Stratego at full boot to boot split, followed by 12 oz of Quadris at the second timing is a good program to minimize neck blast in fields with severe disease pressure in Arkansas, 12 oz of Quadris followed by 12 oz Quadris and 21 oz Quilt Xcel followed by 12 oz Quadris are also effective choices. Please keep in mind that Stratego and Quilt Xcel have 35 day PHI restrictions while Quadris has a 28 day PHI, and fully read these labels for other guidelines and restrictions.

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