Area of impact: Leaves
Description: Tiny dark brown spots develop on leaf surfaces and later merge to form irregular brown patches. Infection starts on the lower leaves and works its way upward; infected leaves turn brown and drop.
Pathogen involved: Septoria glycines (a fungus)
Timing/Conditions: Occurs in early season when the first true leaves appear. Later it spreads to other plant parts. Prefers warm wet weather.
Contributing factors: Continuous soybeans and minimum tillage. Overwinters in infected plant debris and can be seed transmitted.
Management practices: Rotation with non-legume crops tillage and fungicides.