Are there advantages to either narrow-row or wide-row planting?
There are multiple opinions on the effect of row spacing on the development of soybean rust, the severity of the disease, and fungicide effectiveness. Research from Brazil does not show differences in rust incidence and severity among different row spacings. In a wide row situation, it is thought that there is more turbulence within rows during a rainstorm which results in greater dispersal of spores throughout the canopy and field. However, in wide rows it can be argued that the microenvironment is less favorable for rust development, because of lower humidity and more rapid drying of dew. Optimal management of soybean rust relies on good penetration and adequate coverage of the plant canopy with fungicides. There also is the opinion that it is harder to get good canopy penetration with fungicides in a narrow row situation. However if sufficient pressure min 40kPa and the right volume (16-21gallons per acre) are used, there should be minimal problems.