In summary the seed treatments improved yields across the three locations in both 2017 and 2018. In the Peking variety the fungicide/insecticide seed treatment increased yields 2.25 Bu/ac and net returns of $9.88 per acre when average across the two years. The Ilevo treatment added 1.78 Bu/ac increase over the fungicide/insecticide and net returns of $6.44 per acre. The full treatment of Ilevo + fungicide/insecticide increased net on average of $16.32 per acre compared to the nontreated. In the PI88788 variety the fungicide/insecticide seed treatment increased yields 2.60 Bu/ac and net returns of $13.70 per acre when average across the two years. The Ilevo treatment added an additional 3.07 Bu/ac increase over the fungicide/insecticide, which had a net return of $19.33 per acre for the Ilevo portion. The Peking genetics may be providing a lower response to the Ilevo seed treatment, since it has a stronger line of genetic resistance. This was more evident in 2017 and not in 2018. The best treatment in the PI88788 was the Ilevo + fungicide/insecticide which Seed Treatment Plot #1 Plot #2 Plot #3 Multi- Location Average Net $Ilevo F/I 4.05 3.92 7.22 5.07 $ 25.65 Ilevo 2.61 2.67 2.96 2.75 $ 15.46 F/I 1.45 1.25 4.26 2.32 $ 10.19. Peking Variety Average Yield Increase Across Locations Seed Treatment Plot #1 Plot #2 Plot #3 Multi- Location Average Net $Ilevo F/I 6.23 9.87 4.85 6.98 $ 44.83 Ilevo 3.41 4.98 2.43 3.61 $ 24.06 F/I 2.82 4.88 2.43 3.38 $ 20.77. PI88788 Variety Average Yield Increase Across Locations Seed Treatment Plot #1 Plot #2 Plot #3 Multi- Location Average Net $Ilevo F/I 5.14 6.89 6.04 6.02 $ 38.25 Ilevo 3.01 3.83 2.70 3.18 $ 21.35
F/I 2.13 3.07 3.34 2.85 $ 16.90. Average Yield Increase Across Locations
27 increased yields 5.67 Bu/ac with a net return of $33.04 per acre when averaged across the three plot locations compared to the non-treated. When averaging the two varieties together, the best treatment was the Ilevo + fungicide/insecticide with an average yield increase of 4.85 Bu/ac over the non-treated check and a net return of $24.68 per acre. Since the pressure of soybean cyst nematodes were relatively low, it was difficult to determine if the Ilevo seed treatment or the Peking genetics reduced pressure. However that was the trend in one of the plot locations in 2018. In 2017, the Ilevo seed treatment and the Peking variety did reduce soybean cyst nematode pressure based on the soil samples pulled in the plots. Population stand counts were improved with the
fungicide/insecticide seed treatment. The imagery showed that the Ilevo seed
treatment typically resulted in a stay green effect later in the season. Yields can be
increased with a stay green effect if it helps improve seed fill. The conditions in August and September 2018 provided adequate moisture to take advantage of plant greenness by potential improving seed size. Some of the big yield responses to Ilevo in 2018 may be due to the extended plant greenness coupled with timely rainfall. In 2017, the conditions in August were very dry which may have reduced the potential gain in yield from a stay green affect. As the plants exhibit the halo effect from the Ilevo, the plant response may be resulting in shortened internode length. Shortened internodes can lead to an increase in total nodes and pod numbers with a shorter plant. In 2017, the mid-season photos did indicated that this maybe occurring in the PI88788 genetics, which is the variety that resulted in a greater yield increase from the Ilevo. This was not as evident in 2018. In 2018, SDS visual symptoms were greatly reduced with the Ilevo seed treatment. In general these plot locations were relatively low in SCN pressure and had only one location had visual SDS symptoms, yet yield responses to Ilevo were still
found. In summary, Ilevo + fungicide/insecticide seed treatment would be
recommended. In Michigan the majority of soybeans sold with SCN resistance have PI88788 not Peking.