Symptoms begin as small brown spots that can have a yellow halo around them, as spots coalesce the leaf may turn yellow (Figs 1 and 3).
Infected leaves may drop prematurely (Fig 2).
If symptoms remain in the lower canopy, yield is not usually impacted.

Fig 1: Septoria brown spot in the lower canopy

Fig 2: Leaf drop due to upper canopy infection

Fig 3: Early symptoms of septoria brown spot

Management

The pathogen overwinters on infected leaf and stem debris.
Rotation to non-host crops like corn and small grains can reduce pathogen survival.
Susceptibility varies across soybean varieties, but since there are no known sources of resistance, ratings for this disease are not often provided.
If disease is rapidly moving up the canopy, fungicides can be applied according to the label at the R3 to R5 growth stages to slow disease spread into the middle

References

Crop Protection Network (2022, Jan 25).

Septoria Brown Spot of Soybean. Retrieved

from:https://cropprotectionnetwork.org/encycl

opedia/septoria-brown-spot-of-soybean

Authors: Madeline Henrickson and Dr. Alyssa Koehler

UD Cooperative Extension

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