At $13 a bushel, the net return from using these materials is roughly double the cost of the fungicides and application costs.

The biggest yield response came in 2009, with an average yield increase of 11.6 bushels per acre for treated versus untreated plots. 

By comparison, the lowest response to fungicides in the Virginia researcher’s ongoing six-year study came last year with a 2.9 bushel per acre yield response to fungicides. In 2010 and 2011 there was no significant yield increase using fungicides.

However, Phipps points out that strobilurin/triazole tank-mixes did reduce disease incidence significantly in both years.

In general, a lower response to fungicides came in years with persistent hot-dry seasons (2011). This trend could be particularly important to soybeans growers in the Upper Southeast for the next few years.

For the past two years, the region has been dominated by a persisting La Niña weather pattern. Reoccurring La Niñas have been infrequent and sporadic over the past 50 years.

However, for as long as weather records have been kept, there has never been a three-year reoccurring La Niña system.

Take away weather-influenced hot and dry patterns over the past six years, and the yield increase from pre-mix application of triazole-strobilurin fungicides would almost certainly have been higher.

There are a number of pre-mix fungicide options for use on soybeans for 2012. While any of these can be used effectively as a stand-alone product, best results have come from tank-mixing these two families of chemistry.

Mixtures of different chemistries will likely lengthen their longevity by reducing or delaying resistance problems associated with over-use of any one family of active ingredients.

In a series of ongoing tests over the past 11 years (2000-2011), Phipps has tracked similar responses to fungicides when these materials are applied to wheat. The average yield increase over the 11-year period, ending with the 2010-2011 wheat crop, was 11.35 bushels per acre.

In 2004 and 2005, wheat yields were increased an average of more than 23 bushels per acre by fungicide treatments. As with soybeans, the lowest response to fungicides came in 2010 and 2011 when yields increased an average of about four bushels per acre.