Evaluation of Row Spacing, Planting Date and Fungicide Application on Soybean (Glycine max) Growth, Development and Yield.

During the growing season, the mid-southern U.S. typically experiences conditions that are conducive for pathogen development. It is now common for soybean producers in this region to apply fungicides at the R3 growth stage for yield loss prevention. In search of additional management strategies, producers in this region often question if crop establishment on a narrow row pattern would alter environmental conditions within the crop canopy, ultimately influencing disease development and soybean yield. However, limited data exist to support a need for alternative disease management strategies across different soybean row spacings. Therefore, the objective of this research is to evaluate the effects of preventative fungicide applications across multiple planting dates and row spacings on soybean growth, development, and yield.

Experiments were conducted in 2018 at the R.R. Foil Plant Science Research Center near Starkville, MS and Black Belt Branch Experiment Station near Brooksville, MS. Three row spacings, ultra-narrow (38.1 cm), narrow (76.2 cm) and wide (96.52 cm) row soybean were planted on two planting dates, mid-April and late-May. Fungicide treatments included Quadris_® (Azoxystrobin), Quadris Top_® SBX (Azoxystrobin, Difenoconozole), or the combination of Priaxor_{® (}Fluxapyroxad, Pyraclostrobin) and Domark_® (Tetraconozole ). Applications were made at the R4 growth stage using a backpack sprayer and handheld boom containing Teejet Turbo Twinjet 11002 spray tips. An untreated check was included for each row spacing and planting date for comparison purposes.

These data indicate soybean planted in mid-April resulted in greater yield compared to soybean planted in late-May. Results also suggest soybean yield was greater in an ultra-narrow row system when compared to a narrow or wide row system. Application of fungicide was not significant regardless of row spacing or planting date. These data suggest that maximum soybean yield is achieved when planted on ultra-narrow row spacing in an ESPS production system.