Brown Spot

Septoria Brown Spot - Coalescent Lesions Close Up Photo Credit: Melvin Newman - Emeritus - UT

Septoria Brown Spot – Coalescent Lesions Close Up Photo Credit: Melvin Newman – Emeritus – UT

Brown spot (also called Septoria brown spot) is caused by the fungus Septoria glycines, and it causes irregular, dark brown spots usually in the lower canopy. Lesions vary from minute specks to 4 mm in diameter and adjacent lesions may coalesce to form irregularly shaped blotches. With highly susceptible varieties and during wet, warm weather lesions can spread across the canopy and cause premature defoliation. Lesions can also occur on stems, branches, petioles, and pods but are not sufficiently distinct to be diagnostic as herbicide burns early in the season look very similar.

  • Timely fungicide application when warranted can reduce disease and protect yield. Links to Fungicide Efficacy Table – mobile version or pdf
  • Rotation to non-host crop for at least 1 year or more is an effective management options when warranted.

Septoria Brown Spot - Coalescent Lesions Photo Credit: Melvin Newman - Emeritus - UT

Septoria Brown Spot – Coalescent Lesions
Photo Credit: Melvin Newman – Emeritus – UT

 

Septoria Brown Spot - Close-up Photo Credit: Heather Kelly
Septoria Brown Spot – Close-up
Photo Credit: Heather Kelly

 

septoria brown spot in lower canopy
Septoria Brown Spot in Lower Canopy
Photo Credit: Heather Kelly