As with stem canker and top dieback symptoms, the common Fusarium root rot is expressing a very destructive side of the disease. This is Fusarium Wilt. Fusarium wilt as the name suggests causes a wilting of the soybean plant. This wilting has often been misdiagnosed this year as Phytophthora root rot or Phytophthora wilt even though many of these plants have had dry conditions for most of the season. From a distance the affected plants do look to have Phytophthora root rot.
Affected plants have a wilting of the stem tips and the upper leaves are scorched.
In severe cases the leaves will dry up and drop prematurely leaving the petiole behind. The leaves usually remain attached to plants killed by Phytophthora root rot. There also is no evidence of a stem lesion or external decay does not go above the soil line as with Phytophthora. A lenthwise cut through the roots and stem will reveal a browning of the vascular tissue and pith. This may be confused with early-season brown stem rot.