Fungicide seed treatments for winter wheat are available to control most soil and seed borne fungi that cause certain diseases and subsequent yield loss.  Of course, the disease(s) must be present for yield loss to occur and the cost of the seed treatment to be justified.  From 1988 through 2000, UW researchers conducted ten experiments (23 environments) with fungicide seed treatments with an average yield gain of only 1.2 bu/A.  The highest yield response was 3.3 bu/A and the lowest was -0.6 bu/A. 

        In 1999 and 2000, and insecticide plus fungicide seed treatment was evaluated.  This increased the yield response by 0.6 bu/A over the fungicide alone in 1999 and by 5.0 bu/A in 2000.  The insecticide treatments (Gaucho) are used to prevent economic damage from Barley Yellow Dwarf Virus (BYDV), which is spread by aphids in early fall. 

        This brings us to the 2003 seed treatment trials (Table 1). The conditions present in 2003 were clearly conducive for economic returns to both fungicide and insecticide seed treatments.  In fact, the response to just applying the fungicide was double the greatest response obtained in any of the previous experiments since 1988.  Can we count on this magnitude of response every year? No.

         Throwing the 2003 data into the mix, the average response from fungicide seed treatments has been 1.7bu/A over 11 experiments.  In most years, this is enough to pay for the treatment cost.  Only three years of data is available for insecticide seed treatment use.  The average response is just over 4.0 bu/A but the cost of the treatment is significantly higher. 

        A historical analysis of winter wheat seed treatment data shows that responses to seed treatments have been greatest in years where yields have been high.  This is somewhat contrary to the thinking that seed treatments will be most responsive under poor growing conditions.  Further, seed treatments seem to be having a greater positive impact on yield and test weight than on germination.