Septoria Brown Spot
Symptoms:
- Infections begin on lower leaves and develop later on upper leaves.
- Small dark brown spots (pinpoint to 1/5" in size) called pycnidia develop on both surfaces of leaves, the spots may grow together to create irregular brown patches.
- Infection begins on the lower leaves and progresses upward.
- Infected leaves turn brown and yellow and may drop prematurely.
- Septoria brown spot is a common foliar disease that has been reported to cause insignificant to minor losses.
Pathogen Involved:
- Septoria glycines (a fungus). It infects many varieties of legumes .
- This pathogen overwinters on infected plant debris and may be seed transmitted.
Time of Occurrence:
- Often appears on the first true leaves in the spring and progresses to other leaves and plant parts throughout the season.
Conditions Favoring Disease:
- Wet, warm weather, continuous soybeans, and minimum tillage.
Disease Management:
- Rotate with non-legume crops.
- Resistant varieties are not available.
- Tillage and fungicides may be warranted under some conditions.