In recent years, the number of Phytophthora samples from varieties with the Rps-1k gene has increased dramatically and such a trend suggests possible changes in Phytophthora races in Iowa. For the rest of the season, incidence of Phytophthora root rot is likely to be higher than normal in some regions because periodic rain is ideal for its occurrence. Enlarge Reddish-brown lesion of Rhizoctonia root rot. Enlarge Bacterial blight on soybean. Iron chlorosis-associated fungal root rots are prevalent this year.
Infected plants appear yellow and stunted.
They may have poor root systems and poor nodulation with reddish brown or dark brown lesions on taproots. Soybean becomes more susceptible to these fungi when weakened by stresses. Agronomic practices that enhance plant vigor are effective in managing root rot diseases and there is no remedial action that can be taken. Plants with light root rot often can grow out the problems. Use cultivation to mound soil around the plant base and promote root growth.